Dolep lock assembly tutorial (long, many pics)

[Hemo]

Greetings, all,

I recently completed assembly of Jim Kibler’s Dolep flint lock casting set. Except for some final polishing and engraving tweaking, it looks like a done deal!


 






Several  people on the ALR site expressed interest in having me post a tutorial on my experience putting this together. I took digital documentation photos of pretty much everything I did along the way, so at the risk of creating information overload, here it all is, including successes,  epic  failures, disasters and recoveries.

DISCLAIMER:   
This is my first ever attempt at assembling a lock from raw castings. I wanted to attend Mark Silver’s class on lock assembly at the WKU seminar but couldn’t make it. I have no formal training as a machinist or professional gunsmith. Consequently, I was very much flying by the seat of my pants during this project.  I did get some telephone and online help from Jim Kibler, Tom Snyder, and Dave Person which was invaluable.  In no way do I claim this is the only or best way to do things, it’s just what I ended up choosing to do, and it appears to have come out with an adequate result.  I welcome input from anyone who actually knows what they’re doing!
I intend to post this material in small doses in a series of posts over the next few days. If it’s too much or too little info, please let me know.

NOTE:  Throughout this tutorial, the images posted are described by the text BELOW the images.

GETTING STARTED:





Above is the set of castings pretty much as received, except for cutting off the casting gates and some minor cleanup on the lockplate  surface with a file. Note that no holes are spotted or drilled. The axes of the tumbler shafts are a bit askew.  The screws were supplied by Tom Snyder, who made up this screw set for Mark Silver’s lock assembly class.  Tom also included a full size copy of the lock plate with measurements of the hole positions (shown). He also provided a nice printed list of the screws in the set, where they go, and some tips for assembly.





The unslotted screws will need to be finished as they are used during assembly. I slotted the screws with a jeweler's saw and then shaped/widened them into a historically correct V-shape using a slotting tool I got from Brownell's years ago. (These little files have gotten pretty pricey in recent years!) Heads of the screws can then be shaped, rounded, and polished using files and fine sandpaper with the screws chucked in a high speed drill or drill presss.

 
 
I used a basic heavy solidly mounted bench vise. A variable-angle vise would be nice. The picture shows a small inexpensive hardware store rotating ball vise with rubber jaws clamped in the main vise. The little ball vise is useful for filing and engraving at odd angles. I also have a couple of drill press vises and an antique hand vise.  You’ll need various sizes of C-clamps and vise grips.

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Casting gates need to be cut off and-or ground off with a hacksaw and grinder.  A belt sander is good for finishing up these cuts.  The fellow on the right is a wide Sorby sharpening system belt sander which is expensive overkill.  A cheap imported one-inch belt sander does fine, but don’t expect much longevity or precision. My little one-inch wide Chinese belt sander is bordering on life support, but I still use it more than the big Sorby thing.





Most cleanup and basic shaping is done with files after roughing out with grinder and belt sander. I mostly used medium to fine pillar files in #2 to #4 cut, and invested in some rather pricey Swiss needle files (at least pricier than what you get in the hardware store sets),  including a “knife” in #4 cut, half-rounds in #4 and #6, curved riffler files in #2 and  #4, and some assorted oddball shapes as shown.

You could file off the decorative engraved borders and floral engraving and make a fairly plain but functional lock. I wanted to preserve as much as I could of the decorative engraving.  In many places, the castings show only a hint of what the original engraving looked like, and I followed these lines the best I could to reconstruct the original engraving.  The big square graver, with a chasing hammer, worked okay for defining the bold edges of the borders, but  was a little too coarse for the really fine interior engraved lines. I used smaller sharper-angled lozenge-type gravers to do this, using a very light chasing hammer or just hand pressure.  Much anxiety and compromise ensued. More on that later.
A hard sharp scriber, center punch for drilling operations, and a good digital caliper will be essential.



My historic approach to use of drill bits and taps is the hunt-and-swear technique.  Since there are multiple sizes and designs of screws, thread sizes, taps, and reamers needed for this project, I decided to go considerably more anal compulsive in my organization of these tools than is my usual habit, to avoid needless tantrums.  I put together  this little block to organize the various drill bits, taps, and dies into size order, including tapered and bottoming drill bits and taps, clearance drills, and reamers into a logical sequence.  You can read the various sizes of the tools. God help me if I ever knock this thing over. The paired taps and bits are tapered and bottoming pairs. Bottoming drill bits can easily be made by taking regular tapered bit and cutting off the tip on a belt sander.  Note also you will certainly find a digital caliper useful! This one was pretty inexpensive and works beautifully.



You won’t  probably need these until you get to final finishing.  After filing operations, you will have file marks showing.  I used these devices to clean up the marks. The colored plastic tools have belts of abrasive around them in various medium to fine grits and are nice for getting into corners, or inside v-springs. When the surface clogs up, you can just rotate the belt to a new surface. When the belts wear out,  you can cut them into one long strip and use them like emery paper in dental floss fashion.  You can find this set on Amazon as “sanding stick finishing kit by Lumberton” for about 25 bucks. The set includes replacement belts in all the various grits, but unfortunately the grits are not marked on the belts, so you have to go by feel.
The stones will get you to a finer finish.  A hard 320 grit stone with stoning oil will do some detailed shaping, but will leave scratches. Ultrasoft 320 and 600 grit stones , especially with stoning oil, will take these out but are too soft to do much shaping.  Tom Curran (Acer) wrote up a very nice tutorial on the ALR website on lock finishing at this site:

http://americanlongrifles.org/forum/index.php?topic=2585.0

The final tool I’ve found useful is this beautician’s “Tropical Shine” nail polishing stick. There are four different grits on this stick, labeled 1-4. I’m not sure exactly what grit they are, but #1 does a surprisingly aggressive job of making a nice broad flat surface, and if you progress to #4, you can bring steel surfaces to a near mirror shine.  Unlike coarse emery boards, these sticks have a semi-soft foam backing which follows the contours of a curved surface (i.e. lockplate or cock) beautifully.  You can pick these up at your local beautician's, or have your wife go in for you if you don’t want to get funny looks. They are also available on Amazon.







I have two drill presses, one solid and heavy for precision work, and a little one with rapid change variable speed for quick knock-off jobs, including shaping and polishing screw heads. I show this one with my cheapest tool, a nail with a rectangle of fine grit sandpaper fixed onto the nail with a piece of masking tape and wound clockwise. On high speed, this little device can polish the interior curve of a gooseneck cock, the inner curve of a mainspring claw, or the curved bearing surface of a tumbler toe.  Lightly applied, it can polish up the inner surface of the tumbler shaft hole on a lock plate. (Caution-edges can be rounded off!)



You pretty much have to have access to a lathe to get the tumbler shafts cleaned up and true. If you don’t have one, cultivate the friendship of a machinist who does.  This is my very own Chinese Harbor Freight mini-lathe. I had no experience with a metal lathe before this, but after getting set-up help from a machinist friend, I lost my fear of it and found it easy and fun to use.  (“Don’t wear a tie!” the safety instructions all say.  Does anyone ever actually wear a tie in their workshop?)



This is another tool you don’t necessarily have to have, especially if you’re good at eyeballing the color of hot steel under a torch or in a forge. The frizzen will need to be hardened, as will the tumbler and sear. Three springs will need hardening and tempering. Tempering of all these various parts is done at different temperatures.  Jim Kibler specifies hardening all parts (except the lockplate, cock, jaw,and screws) at 1525F with an oil quench, tempering the frizzen to 375F, tumbler and sear to 575F, and springs to 750F. An oven setup like this can bring a lot more precision to the process.  As I’ll describe later on, after a few suboptimal results and one or two disasters (broken springs), I ended up deviating a good bit from these recommendations.
Anyway, this is my newly acquired Neycraft 110V electric oven/kiln, bought used from E-Bay, and Sentry digital controller, bought new from Rio Grande. Connection required minor disassembly and interior rewiring. I intend to use this setup in the future for things like Delft clay metal casting, lost wax casting, as well as future lock work.  I wouldn’t recommend buying this whole setup just to make one lock set, obviously. Thanks to “Smart Dog” Dave Person for helping me get this all set up!



Hot burning gases—a pyromaniac’s friend!  You can probably heat treat your parts with just MAPP gas or a forge.  I ended up using this little portable Harbor Freight acetylene torch to do some serious heat treating and spring bending. More on that later.  The little refillable butane torch is really handy for small precise soldering jobs.  (Yes, I had some mishaps requiring the use of solder and silver braze. More on that later, also.)







Drilling operations are going to require a stable base for the lock plate, in particular. I took a piece of squared scrap maple from the end of a stock blank and made this support block. I band-sawed a rectangular recess on the edge to accommodate the bolster of the lock plate, and after I started installing the bridle parts, I cut out a recess to accommodate the bridle.  Due to the round face of the lock, I thought I’d have to make some sort of support cradle with plaster of Paris or Bondo to stabilize the lock when drilling from the inside, but in fact there are two parallel flat surfaces on the round face of the lock plate, one under the frizzen spring and one under the cock, and using these two flat surfaces, clamped to the drill press , it was pretty stable.  I wouldn’t fault anyone for making a custom curved cradle for this purpose, though.  A dedicated drill press clamp would have been useful, but I didn’t have one and made do with C-clamps.

And finally:



Years of accumulated miscellaneous tools, doodads, geegaws and foofurraw.  I’m sure I’ve missed something on the materials list, but it’s probably hanging somewhere on this pegboard or in one of the drawers.

Okay, that was a long post and probably quite enough for a start!  Next time around, I’ll post about the actual procedure used to assemble this beast.

Again, please let me know if this is too much or too little info, or just tell me to shut up. Feedback is appreciated!

Gregg
 

[Hemo]

DOLEP LOCK ASSEMBLY TUTORIAL #2

Hello, again,

Today I’m going to talk about cleaning up the lock plate and starting to attach parts to the plate, specifically the frizzen and frizzen spring. These parts are pretty simple to put on, and a good start to get your feet wet before going on to the tumbler and bridle.





In a conversation with Jim Kibler before I started assembly, he said that some people had problems with random hard spots on the castings on his earlier run of locks (of which mine was one) and offered to re-treat (anneal or draw back) my frizzen, springs, tumbler, and sear at no charge. I sent these parts to him, and while I was waiting to get them back, I used the time to inlet the stay-at-home lock plate into a pistol blank I was starting.

The first thing to do is make sure your lock plate is not warped, especially on the inner surface. Mine was pretty flat except for a few very shallow shrinkage dips and hills on this surface. I used a broad flat file to go over the inner surface and take these down to a flat plane.   I used a fairly coarse large file to do this and got some deep file marks in the process.  Be sure to card your file frequently and pick out the fragments stuck in the teeth, because these file marks are going to have to be polished out eventually.  Clamp the lock plate firmly in a vise during filing to help keep a flat surface going, and pad the jaws of your vise somehow to keep the vise from marring the edges.  Try to make file strokes in one direction along the axis of the lock plate.  Around the front and back of the bolster area, you will need to make some crossways file cuts, but be careful not to dig into the flat surface you’ve established below the bolster. The inner surface of the bolster also needs to be filed flat.

You don’t necessarily have to do any serious surface finishing on the curvy outer surface of the lock plate at this time, but should file the flat areas under the frizzen spring, frizzen pivot surface, and underlying the cock in one nice parallel plane. This will help you keep everything square when you start drilling the lock plate face-down from the inside.

It wouldn’t hurt to go ahead and file a shallow draft around the edge of the lock plate at this time to aid inletting, but you could probably wait until later. The edges of the lock plate are likely to pick up some dings during construction, which would require re-filing the draft on the edge.



If you want to do some preliminary cleanup on the rounded face of the lock at this time, go ahead but be careful not to cut off the shallow cast engraving impressions on the surface of the plate. In particular, the sear screw hole position right behind the cock is indicated by a nice little engraved half-circle in the casting, and is one of the few places on these parts where a screw hole position is clearly indicated. Save it for when you start drilling the bridle parts!



Time to start attaching the appendages! The bottom surface of the pan cover of the frizzen and the pan surface need to be filed flat so they meet cleanly. The inner and outer surfaces of the eventual pivot hole site of the frizzen should also be filed flat and square. This will eventually be a bearing surface. The inner edge of the frizzen where it will contact the barrel also needs to be flat and square.  In my case, since I already had the lock plate and barrel inletted, it was easy to firmly position the frizzen in position against the pan and the barrel surface. Make sure that when your frizzen is firmly up against the plane of the barrel, the future pivot hole site on the frizzen is also firmly up against the side of the lock plate.  It may take a little dressing with a file to accomplish this.
 
As you can see, the pan cover of my frizzen  doesn’t extend to the edge of the pan itself. I’m not sure if this is a result of overly vigorous filing on my part, or if that’s just how the casting is. I don’t think it was like that on the original lock.  I may have to round off the upper surface of the edge of the pan at some point to make this less obtrusive.

After you’re happy with the fit and position of the frizzen on the plate, you’re going to fix it in position for drilling the pivot hole. Some people use super glue (ACC) for this, some epoxy, some solder. After an initial failure with super glue (fell apart immediately), I moved on to five-minute epoxy, which worked for me.  Apply epoxy all around the pan and clamp the pan and frizzen firmly together to prevent gaps. Make sure after applying epoxy and clamping that the pan cover edge is still aligned with the edge of the lock bolster, and the pivot site is up against the side of the lock plate. At this point, I let the epoxy set up overnight, sat down and popped a cold one.



Next day, after convincing myself that the frizzen was firmly expoxied in good position,  I eyeball-spotted what I thought would be the best center of the frizzen pivot and punched a center hole.  I then placed the lock plate and frizzen in my custom-made wood drilling block and clamped the whole thing firmly in my drill press. The frizzen will be held by an 8-32 screw passed into the plate. There is no bridle on this lock.  Take a deep breath and drill a hole passing all the way through the frizzen and through the lock plate. This hole should be drilled cleanly through with a #29 drill bit, the size appropriate for tapping the plate to 8-32.
While this assembly is in position in your drill press, you could proceed with drilling the clearance hole through the frizzen.  Clearance hole for an 8-32 screw is nominally a #16 drill bit. A really compulsive machinist might find this fit a little sloppy, but that’s what I used. Set your drill press stop to end at the bottom surface of the frizzen without penetrating the #21 hole in the lock plate! (Edit--Bob Roller just informed me that the setup will be more stable if the un-threaded portion of the screw extends a short distance into the plate!)

After drilling, the pan can be removed from the plate. Several  complex techniques have been described to accomplish this, but I found an accidental drop onto a concrete floor worked quite well.  (A sharp rap with a mallet or screwdriver handle will probably accomplish the same thing).



I actually didn’t tap the hole for the frizzen screw until later, but there’s no reason not to go ahead and do it now. As always, with tapping, go slowly and gently, with the plate firmly fixed in a vise, tap going in perpendicular, using tapping fluid, backing out the tap a turn or two frequently to clear out the chips. Back out if you meet resistance.   The plate should be tapped all the way through to the back surface.  You can try out Tom Snyder’s pre threaded frizzen screw at this time, if you have his screw set, and make sure nothing is binding up. The screw on the inside of the bolster needs to be filed off flush with the bolster surface.






With the frizzen in place, you can move on to the frizzen spring.  The spring casting will need some general  cleanup with files, taking off casting gates and casting flash.  There may be some excess metal hanging on the leafy finial area, and possibly inside the curve of the spring. This stuff can be cleaned up with files.  It’s not necessary to bring the fine details and spring surfaces to a polished finish at this time, but the back surface of the spring, where it will contact the plate, needs to be filed flat and true with no dips or bulges which will raise the spring off the plate.  High spots are likely to occur right next to the fixation post. Be sure to file these areas flat and true with the rest of the spring surface, and extend the flat surface onto the round blobby site of the frizzen spring screw.  Gently file the fixation post round and clean.

The area of the finial behind the screw bulge is a little problematic.  The upper edge of the floral part of the finial is likely to bump into the curved surface of the lock plate and prevent the spring from lying flush against the plate.  A little metal removal will be needed here.  Some filing along the upper back surface of the finial will get you closer. A little grinding with a small cylindrical stone in a Dremel  tool  may take you a little further.  Since the finial is fairly small and thin, you could heat it red hot with a butane or propane torch and gently twist it to conform to the curve of the lock plate. I did a little of all of the above, and got the whole surface of the spring pretty flush against the plate.
 
The frizzen spring is held in place by a protruding post entering the lock plate, and a recessed screw passing through the back of the plate. The site of where the screw needs to go is pretty well indicated by the round flat portion of the lock plate rising above the curved surface of the plate.  Start by drilling for the position of the post, though. This hole should be drilled, by my measurements, at a perpendicular intersection 0.470” back from the rounded front tip of the lock plate and 0.135” up from the lower surface of the plate.  If you have Tom Snyder’s copy of his screw positions, this well help. 
After filing the bottom surface of the frizzen spring flat and cleaning up the post, you can see the post is a pretty tight fit at  3/32".  After spotting the post hole location with a center punch, put the plate in your drilling block and and drill your spotted hole all the way through the plate to 3/32".



Some people have posted worries about the upper arm of the frizzen spring being too short for contact with the cam of the frizzen.  As you can see here, with the frizzen spring just positioned within the spring’s  post hole and pushed up against the cam,  there is plenty of room for the frizzen cam to make  good contact.
The frizzen spring fixation screw placement comes next.  As I said above, the position of this screw is pretty well indicated by the round flat protrusion rising above the curved surface of the lock plate. You can eyeball-spot the center of this and make a center punch mark on the front surface of the lock. The frizzen spring is fixed by a pretty small 4-40 screw with a 3/16” diameter head.  The clearance hole for this screw was made clear through the plate from the front surface with a #31 drill bit. Since the 4-40 retention screw underlies the mainspring on the inside of the lock, the screw head will need to be recessed or flush with the inner surface of the lock. From the back of lockplate, you need to drill a recessed hole big enough to bury this 3/16” screw head below the mainspring, but not all the way through the lock plate.  A 3/16” drill bit passed a SHORT distance into the plate from its back side, followed by a squared-off bottoming bit of the same size, will provide a nice place for this screw head to live. If the screw head won’t fit this hole, you can chuck this little screw in a drill or drill press, being careful not to crush the threads, and can reduce the diameter of the screw head by applying lateral pressure with a flat file against the side of the screw head until it fits.  Create a nice tapered screw slot using the technique described on my previous post. I like to round off my screw heads, but this is one you can leave square.

Now you will need to drill and tap a hole into the bulbous part of the lower arm of the frizzen spring.  If memory serves correctly, I think I did this by placing the flat outer surface of the spring on the base plate of my drill press, and drilling a hole into my best guess at the center of the frizzen spring screw bulb.  The 4-40 screw requires a #43 drill bit for tapping. I drilled this hole directly into the spring from the back of  the bulb, being careful not to go too deep and penetrate the outer surface of the spring bulb, which tapers as it moves up from its base on the plate.






I was not very happy with the result. Although the spring was in adequate position for functional purposes, the bulb was positioned a little too low on the plate for my taste, causing the line of the lower arm of the spring to not nicely parallel the lower surface of the lock, and the spring bulb looked a little un-centered on the lock.

If I were to do it again. I would have epoxied the frizzen spring onto the plate after drilling the plate holes, making sure I was happy with the position of the spring before drilling the screw hole into the spring. As it turned out, I ended up correcting this situation when I made my second frizzen  spring. (Yes, there were two. Read on in the next installments!)

Until next time,

Gregg

[Hemo]

DOLEP LOCK ASSEMBLY TUTORIAL #3

Hello to all again,

I hope you’re ready for a long one.

I’m  going to cover preparation and installation of the tumbler and bridle in this entry. Before that, however, there’s one more thing I should have covered previously in the frizzen tutorial:



Even after clamping and epoxying the frizzen in place during installation, you’re likely to get some gaps between the pan cover and pan. Check this, roughly, by holding the closed pan cover and lock plate up to a light to see where it needs work. If you can see no light, you’re good, but the epoxy bond doesn’t allow for perfect contact. After cleaning off the epoxy residue from both parts, which you can do with a scraper and acetone, you can identify the points of contact and non-contact using some sort of transfer color applied to the joining surfaces. You could use inletting black, which makes a huge mess, traditional smoke from an alcohol lamp (charming and authentic, but too tedious for my taste), or even lipstick. In this picture I am using Dykem mechanic’s blue, a fairly quick-drying liquid applied from a screw top can. It cleans up quickly with acetone.  I applied a coat onto the upper edges of the pan, and closed the frizzen before it dried. I then used a fine pillar file to gently take the high spots down on both the pan and frizzen, repeating until the gaps went away.

MOVING ON TO THE TUMBLER AND BRIDLE:

The tumbler is the beating heart of the lock, and it’s critical to get it finished and installed square and clean in relation to the plate and bridle. The tumbler casting in this set, right out of the package, has long extensions added to the inner and outer axle shafts, which make this part much easier to handle and machine than trying to use the stubby original length shafts, but unfortunately these extensions are not totally true and square, a bit lumpy, and slightly off axis to one another.  You can place one of these shafts in a vise and gently, by eyeball, cold bend the other until shaft until it appears straight. You could also chuck one or both shafts in a drill press or drill, and gently marking the spinning surface with an ink marker or file, identify where the high spots are. The tumbler will then need to be finished up on a lathe.



The large outer shaft will be placed through a reamed hole in the lock plate measuring 9/32” diameter, and the small inner shaft with go through a reamed hole in the bridle measuring 3/16”. Turn each shaft down on the lathe to just smaller than these dimensions, respectively.  At this point, a little too tight is better than too loose, since the shafts will be further polished later. A metal diameter index plate is useful to test the diameters as you get close to finishing the lathe work.
The inner and outer surfaces of the main part of the tumbler can be carefully faced off on the lathe to keep them perpendicular to the shafts.  The other various surfaces of the tumbler can be dressed with files.



At this point, the sites of the holes for the bridle and tumbler need to be established. As I posted last time, the most clearly visible landmark for a screw placement on the plate is the sear screw, lying just behind the cock. The little half-circle of decorative engraving on the outer surface of the lock is your target. Mark this with a center punch right in the middle. Then place the plate face up in your drilling block, clamp, and drill clear through the lock with a #29 drill bit (to accommodate later tapping with a 10-32 tap).  Note that I’m starting this hole with an undersized center drill before going on to the full sized bit. I used the center drill to start just about all holes to keep the final drilling accurate.

The next major hole site you need to identify is for the tumbler shaft.  On the outside of the lock casting you can see the general shape and location of the plugged tumbler hole, but it’s far from precise. What I’m going to do is find where this hole needs to go from the back side of the lock and drill right through the plate and cock at the same time.





The position of the cock is critical for function.  Similar to the frizzen, I fixed it to the lock plate with epoxy before doing any drilling. The cock should be positioned with the flat stop on the inside edge of the cock resting firmly against the top surface of the lock plate, flat surfaces flush against each other. Based on pictures of the original lock, the tip of the lower jaw should lie just about a millimeter or slightly more above and in front of the top edge of the pan fence. These two landmarks should get you close, but also check the outside surface of the plate to make sure the back edge of the cock lines up close to the edge of the raised flat plate surface under the cock. (The upper front part of this flat area won’t match the edge of the cock except at half-cock position.)

After mixing your epoxy, apply it generously between the cock and lock plate. You have a few minutes to tweak the cock to final position, as described above, before applying a clamp or vise grip. Check it again after clamp placement to make sure nothing slipped, then let cure overnight.







After curing the epoxy, the tumbler hole site is identified and punched.  According to Tom Snyder’s plan, this hole should be centered 0.497” in front of the center of the sear screw.  He doesn’t specify position from top to bottom, but the hole appears centered slightly above the midportion of the plate, centered about 0.450” above the lower edge of the plate and about 0.400” below the top edge, by my measurements.

The tumbler pilot hole is then drilled from the inside of the plate all the way through the cock. Drill size isn’t critical here, it just needs to be a small hole perpendicular to the plate. It may be a little difficult to stabilize the plate for drilling with the cock glued on the outside, so use the front flat end of the plate for alignment and clamping and square up the drill bit with the plate before gently drilling through.



After separating the epoxied plate and cock (the accidental fall on the concrete floor technique could be applied here), it looks like the tumbler pilot hole is pretty much right in the middle of the round casting mark of the plugged hole.
Now we can go on to prepping and attaching the bridle. We’re not going to ream out the holes for the tumbler shafts until the bridle is in place, then we’ll do both holes together at one go to keep everything square.





We’re ready to start drilling holes for the bridle at this point. The bridle can be cleaned up a bit with files. The surface where the bridle contacts the plate needs to be cleaned up and squared a bit more meticulously.
 
Note that there are two fixation posts on the bridle, meant to enter the lock plate. The upper one is a nice thick round post, the lower a little rectangular nub. Tom Snyder stated in his assembly notes, “Unless you are a masochist, file off the alignment stud on the bridle as well as the little tit on the bottom leg of the bridle. . .they make it much, much harder to position the bridle correctly and aren’t structurally necessary”.  I don’t totally agree. I did file off the little rectangular tit, but left the round upper stud intact. I found having this stud in place helped stabilize the bridle position while drilling the other holes. I’d recommend using it.

The stud hole, by my measurement, lies 0.730” back from the most posterior curved edge of the bolster, and 0.080” down from the upper edge of the lock. You can drill this hole with about a 7/64” or #38 drill bit all the way through the plate, coming from the inside. It will come out underneath the cock and won’t show.

With this hole established, and the bridle post placed in it, the flat surfaces of the bridle that contact the plate should be filed off until everything sits nice and flat on the plate.  Then you can move on to drilling the rest of the bridle holes.





Here, the position of the sear screw hole is marked on the surface of the bridle with a pointed drill bit placed against the bridle while rotating the bridle on the stud. The resulting curved scribe line shows where the hole needs to be drilled, midway between the upper and lower margins of the bridle arm. Center punch and drill this hole with the broad face of the bridle down.  An 8/32” screw goes through this, so drill a clearance hole using a #16 drill bit.

The final hole in the bridle, before going on to the tumbler hole, is at the upper front edge of the tumbler, very close to the edge of the plate.  At this point, you could tap the 8-32” sear screw hole into the plate to fix the bridle into more stable position with the sear screw. With the bridle in position, the front bridle screw can be drilled through the bridle and plate.  This screw is a 5-40, and should be drilled with a #38 drill bit. A clearance hole can then be drilled through just the bridle (not the plate) with a #29 bit. Tap the hole in the plate with a 5-40 tap.

(On the original lock, the front bridle screw was a blind screw not passing through the plate. You could mount it either as a blind screw or through-and-through screw, but there is not very much metal in the plate at this site. I ended up drilling and tapping it all the way through for strength, but the screw does show somewhat on the outer surface of the lock. Your call on what you feel comfortable with. )

The top of the bridle lies very close to upper edge of the lock and may actually rise above the edge slightly.  I ended up filing off  a bit of the upper surface of the bridle and also reducing the diameter of the front bridle screw head to provide clearance for inletting the lock.







With the bridle screwed into position on the plate, we’re ready to drill and ream the tumbler shafts.  As described in my previous posts, at this point I drilled out a recess in my wood drilling support block using spade bits and chisels to accommodate the installed bridle.  The plate is clamped face up in the drilling block, and an 11/64” bit is passed from the tumbler pilot hole in the plate all the way through the bridle. This bit is the recommended size for starting the 3/16” reamer you will use for the final tumbler hole in the bridle. (You could start out with a smaller sized bit first and work your way up.)



The tumbler hole in the plate (but not the bridle) is then drilled with a 17/64” bit, followed by a 9/32” reamer, both drilled in the drill press.  The smaller 3/16” reamer can then be passed through this hole to make the inner tumbler hole in the bridle. With any luck, this hole in the bridle will be surrounded all the way around by metal! (Mine was, though the margins are slim!)





You can now assemble the tumbler, plate, and bridle, screw it all together, and make sure everything lines up and turns freely.







The final fixture in this part of the lock is the sear screw and sear spring. The hole for the sear screw lies pretty far forward, actually lying within a cutout in the tumbler. This one is a bear. It is a small blind screw, 4-40 in size, lying very close to the upper edge of the plate. The hole is very shallow. I drilled it with #43 tapered and bottoming drill bits, being careful to set my drill press stop short of penetrating the outer surface of the plate.

When tapping this little blind hole I had my first fairly bad mishap when the tap broke off in the hole. Unable to extract the tap, I had do drill a separate hole clear through the plate just in front of the broken tap. I was able to get the bits of broken tap out through this hole, which fortunately lies just below the surface of the cock and doesn’t show. I filled up this hole by cutting a short piece steel nail and filling it to fit to make a tight plug. I then tinned the plug with solder, fluxed the hole, and peened the plug tightly into the hole with a hammer. I then heated up the plate and plug with a torch until I could see the solder rise to the surface. I then filed off the repair flush with the plate and redrilled the blind hole. (I didn’t use my best and brightest file to do this cleanup since the solder will clog a file.)  All went well on the second attempt, blind hole drilled and tapped without further mishap.

The sear spring can be cleaned up now, filing the contact surface of the spring with the plate flat and square. The sear spring has a protruding rectangular stud on its upper arm on this surface (don’t file this off!) and you will need to cut a little slot in the lock plate to accommodate this stud.
 
This spring lies very close to the upper edge of the plate, especially at its rear end, so extreme care must be taken not to mount the spring protruding over the top of the plate. After fixing the spring with sear spring screw loosely, to allow the spring to rotate on the screw, I marked the position of the spring stud on the surface of the lock plate with a sharp scriber, above and below the edge of the spring, making sure nothing was sticking beyond the edge of the plate.  I then used a heavy graver and chasing hammer to make a notch between these lines in the plate.  Several passes of the graver were made until the retention stud fit firmly and deeply in my notch, allowing the surface of the spring to lie firmly against the plate.





The sear pivot hole can now be drilled. The position of this hole can be seen pretty clearly on the casting. Spot and drill this hole with a #16 drill bit, to clear the 8-32 sear screw.

You can tap the sear screw hole at this time, if you haven’t done it already, to 8-32. Tapping through the sear hole in the fixed bridle may help you keep the tap straight.



Now you can remove the bridle and check out the position of the tumbler relative to the sear. The tumbler notches and sear nose will need some further refinement for smooth function. But that’s a topic for a later installment!

Happy trails until next time,

Gregg

[Hemo]

DOLEP LOCK ASSEMBLY TUTORIAL #4

Back again for more!

Here’s a postscript from yesterday’s entry that I didn’t have room for, regarding marking and drilling the hole for the tumbler and cock. I drilled them together from the back side of the plate:

(NOTE: Tom Snyder’s assembly notes say that he used a different approach, marking and drilling a center hole first in the outer surface of the cock, then positioning the cock on the plate as described above, then marking the plate through the hole in the cock and drilling the plate from the outside. Either way would work. It’s a little hard to tell from the cock casting where the exact center of the tumbler goes through the cock.)

FEELING COCKY YET?

Today I’m going to talk about putting the parts of the cock together and fixing them to the tumbler.





As with the other parts, casting gates and excess flash should be ground/milled/filed off from the cock and top jaw.  Be aware, however, when cleaning up the top jaw, that the back surface of the jaw, where it contacts the cock spur, it not flat like the back of a Siler jaw, for example, but has a little protrusion that interlocks with  a groove in the spur.  This is how I ended up filing this little stud.  The spur on the cock has this short trough running through the mid third of the spur, and the jaw stud rides in this.

The trough is present on the casting, but rather rough. I found it a little difficult to clean out. Using a combination of needle files and gravers, I cleaned out an acceptable ditch that the jaw spur would fit into. Make sure the jaw stud can lie all the way into this slot without pushing the jaw forward from the spur. The flat parts of the jaw to the right and left of the stud should meet the flat part of the spur.





The jaw is held on by a big 12-24 screw. The clearance hole in the top jaw needs to be drilled to 7/32”. Note that on the unaltered casting, there appears to be a dimple marking the site of the screw. This dimple is way off center—don’t use it!  Do some careful  measuring to center and punch the hole for the jaw screw in the midline of the jaw. This is where I drilled mine.





The top jaw screw needs to be drilled and tapped into the back part of the lower jaw, parallel to the spur. In order to drill this straight, I placed the cock upright in a drill press vise and positioned the spur right up against a mounted #16 drill bit, placing the previously prepared trough right up against the bit. This establishes the angle, but the hole actually has to be drilled slightly forward from this, as shown, to clear the lowermost portion of the spur.



The hole in the cock is tapped  with a 12-24 tap. The cock screw and upper jaw can be tried out for position now.

The cock jaw screw can be artistically shaped with swoopy bulges and rings now or later.  You can use photos of the original lock for guidance, or use some artistic license and make your own design.  I shaped my  screw by clamping the threaded end of  the screw in my drill press and using half-round and pillar files applied laterally to the spinning screw. This could also be done with a lathe.
 
On the original lock, the lower end of the jaw screw, extending below the lower jaw on the cock, was tapered with a little decorative knob at the tip. I did this with files freehand, but if you want this detail,  you might want to do it in your drill press or lathe before shaping the upper bulbous portion of the screw, since the fat cylindrical upper part of the screw can easily be mounted in a chuck if it hasn’t been shaped.
 
The slot for the jaw screw is started in the usual way described earlier, but filed with a larger tapered slot using a knife file to allow use of a larger screwdriver.

REPAIR ALERT:
After drilling and tapping my top jaw hole, the finished 12/24 screw passed into the threads but was very wobbly and didn’t actually catch the threads until it was halfway into the hole. The threads in the hole appeared shallow. I don’t know what caused this. Maybe my #16 drill was a little oversized, or maybe slightly bent during drilling. I actually ended up making a totally new top jaw screw from a piece of 3/8” round steel stock on my lathe, hoping to get a slightly larger threaded shaft, and  threading with a 12-24 die. My new screw was still loose and wobbly.  I eventually remedied this by applying silver braze (Alpha brand, fine silver braze wire and flux in a tube) over the threads.  I didn’t fill the entire hole, just covered the threads, using MAPP gas for heat. I then passed the 12-24 tap through the hole, creating deeper threads into the silver braze and a much tighter screw fit. The silver braze doesn’t show from the outside.

Another quick alteration I made to the cock prior to this was some bending of the top of the spur. The top of the spur hit the edge of the jaw screw. I don’t know if this is present on all castings or just mine, but I fixed this by heating the upper part of the spur red hot with MAPP gas and bending it slightly backwards for clearance, being careful not to bend the mid-to-lower part of the spur.



The cock now needs to be mounted on the tumbler.  The cock is held on by a wide-headed 6-40 screw. The hole for this screw is made by turning the tumbler in the lathe into a fixed  #33 drill bit. Both shafts of the tumbler are still left long at this point, so be sure to drill deep enough to allow adequate tapping after the shafts are shortened.  This hole can be tapped to 6-40 now.




The large tumbler shaft now needs to have four flats filed on it. These flats should taper slightly, broader at the base and narrower at the tip. Leave the base of the tumbler shaft round where it passes through the lock plate, and leave a little clearance separating the cock from the plate. On my tumbler, I left this part of the shaft round to a length of about 0.200”. This might be a little generous,  as the plate measures about 0.165” thick, and there may be a slightly excessive gap between my plate and the cock, but not  much.  Cut nice square meeting shoulders at the junction of the round and squared parts of the shaft to allow solid placement of the cock.





In order to place a square hole in the cock at the correct angle, apply a thin flat glob of soft solder onto the back of the cock.  Place the tumbler in the lock plate into the position it will occupy when the mainspring is fully at rest. (This may or may not be where the tumbler hits the lower arm of the bridle, but close.) Then pass the cock screw through the small pilot hole in the cock and snug it down on the square end of the tumbler shaft, with the cock placed in full-rest position. (Line up the square cock rest on the back of the cock with the top of the lock.)  With both cock and tumbler lined up at full-rest position, tap gently around the edges of the cock screw to make an impression into the layer of solder on the back side of the cock. You can now see where the square edges of the tumbler hole need to be filed in the cock. (The first picture above shows the solder applied but not yet stamped.)

In order to reduce the amount of filing needed for the square hole, I drilled the pilot hole to about 13/64”. (Don’t lose your solder impressions while you do this! You might want to mark your solder impressions with an ink marker or graver to preserve them.) Go ahead and file four flats in this hole, again tapering slightly, narrowest at the outer surface.)  Fit the cock onto the tumbler frequently as filing progresses, gradually working the cock down the tumbler shaft and making corrections as needed. (It’s good to have the extra length on the tumbler shaft at this point in order to make any corrections in angulation before you get to the base.) By the time the cock meets the square shoulders of the tumbler shaft, it should seat very tightly and should require some firm rapping to fully seat it.

At this point, if you’re happy, you can cut off the end of the tumbler flush with the face of the cock, or very slightly below.  The assembled cock, tumbler, and plate can be checked for free movement. Again, with the cock at full rest position, the nose of the tumbler, where it will meet the mainspring, should be where you expect it to lie at full rest. You can use photos of the interior of the original lock to make your best guesstimate as to where this is. (See below.)



That’s all for today! Next we’ll move on to springs, hardening and tempering.

Gregg

[Hemo]

Great tutorial! Only part I find a little unclear, is the truing up of the tumbler shafts. Why bend them? I'd thougth truing ine the lathe woud be adequate.

Best regards
Rolf

Hi, Rolf,

I would guess that if the shafts are only slightly off axis with each other, it could all be done on a lathe, but if obvious angulation is present, you could reduce the amount of metal to be removed and possibly prevent damage to the part or lathe tool by a wildly oscillating shaft by straightening as true as possible before chucking in the lathe. I did end up doing some slight bending by eyeball before lathe work.

Gregg

[Hemo]

DOLEP LOCK ASSEMBLY TUTORIAL #5

Back again! Today I’ll go over positioning the mainspring, hardening and tempering.






Before going into that, I thought I should post some pictures of the outside of the original Dolep lock, above, for those who may not have them, since I posted a picture of the insides last time.

SPRINGING INTO ACTION:

Now that the tumbler is firmly installed, you can use the toe of the tumbler to establish the position of the mainspring. Mainspring position is critical. If it’s too close to the tumbler, the claw of the spring will collide with the tumbler at full cock. It it’s too far forward, it will fall off the end of the tumbler at full rest and take the wood out of your lock mortise when inletted.






Mainspring position is established by drilling a blind hole into the lock plate. This position can be established by mounting the cock on the tumbler, placed in the plate, and positioning the cock at full rest, meaning the flat inner stop surface of the cock lies flush against the top of the lock plate. At full rest, the tip of the mainspring claw should contact the tumbler a very short distance (but not scary close) behind the front tip of the tumbler.

I marked the mainspring stud hole by painting the front inner surface of the plate with Dykem machinist’s blue. I then placed the back tip of the mainspring claw firmly against the front bearing surface of the tumbler toe (at full rest!), and scored a line in an arc across the blue with the tip of the spring stud, the center of the arc being the contact point of the spring and tumbler toe.

The blind hole for the spring stud lies midway between the upper and lower edges of the plate. Center punch this spot. It looks like a 7/64 drill bit is about right for this hole, after cleaning up the lock with files and dressing the stud smooth and cylindrical. (As with the other springs, the surface lying against the lock should be filed smooth and straight right up to the edge of the stud. Later on, you can file off a little from the contact surface of the lower spring arm if you see it scraping on the lock plate.)

Drill a blind hole with tapered and bottoming bits at this site, setting your drill press stop so it doesn’t penetrate the outer surface of the plate. Try placing the stud in the hole. If it doesn’t go all the way in, you can carefully file off some of the tip of the stud until the spring lies flat against the plate. A little rapping with a rawhide or plastic mallet here wouldn’t hurt to get it firmly seated.

The actual measurements for the location of the mainspring stud hole are 2.720” in front of the center of the tumbler hole, 0.720” back from the front rounded tip of the lock plate (assuming you haven’t filed any or much off the front of the plate during cleanup), and about 0.230” up from the lower edge of plate (again allowing a little fudge factor if you have filed some draft into the plate edge.)





The mainspring is held in place by another blind screw measuring 5-40. File the surface of the upper mainspring screw site flat and punch a center hole in what looks like the center of this flat area. Position of this hole is not really critical as long as the upper arm tip of the spring is in contact with the lock plate bolster.  Drill a clearance hole through the spring with a #29 drill. Position the spring stud in its hole and center punch for the spring screw through this clearance hole, again with the tip of the upper spring arm up against the bolster. Mainspring screw hole is drilled with #38 tapered and bottoming bits, then tapped to 5-40 with tapered and bottoming taps.
 
You can try out the fit now, but of course don’t try to flex and mount the spring onto the tumbler until it’s hardened and tempered!  Onto this topic next:

The frizzen, tumbler, sear, and all springs need to be hardened, followed by tempering to various temperatures depending on the part. These temperatures are listed in Tutorial #1.



After these parts are hardened, it’s going to be very difficult to do any more engraving or shaping, so you should clean up and finish these parts as close to final finish as you can now. This particularly applies to the frizzen, which will (should?) come out very hard after heat treating.  You need to decide now how much decoration/engraving you want on the frizzen and do it.

On the casting, you can see a sharp decorative molding line around the front side of the frizzen and some raised floral designs in the middle. The edges of the moldings and inner details can be sharpened up with curved riffler files, gravers, and stones.  The curvy edges around the front stem of the frizzen can also be cleaned up nice and crisp.
 
If you look closely at the casting you can see the faint impression of a very fine engraved double line outlining the shape of the frizzen between the outer edge molding and the inner raised floral detail. I’m sure there are guys out there who can engrave perfectly parallel fine curved beauty lines exactly 1/16 inch apart going smoothly around an arc with no variations in depth or width, and no wobbles. Unfortunately, I’m not one of those guys. I decided I could engrave a credible single line at this site, but there’s no way I could make a perfect double line. I engraved this line with a small tapered graver (not a square) a little deeper than necessary, trying to keep at least the bottom of my line in one nice uniform arc. This took many repeat cuts and adjustments. There were plenty of bobbles and wobbles at the surface. I filed, sanded, and stoned the surfaces down below the level of the irregularities, leaving a fairly uniform single shallow line. (Sometimes perfect is the enemy of good enough.)



All these parts call for initial heating to 1525F followed by an immediate oil quench. If you have a high temp oven /kiln you can use this, but following the advice of other gurus, I decided to do the initial heat treat just using MAPP gas.



I put together this little temporary heat treating furnace using plain bricks. I plugged up some holes between the edges of bricks with Brownell’s Heat Stop mud, just to keep more heat in the central cavity. I made a little coiled soft steel wire support to raise the parts above the floor of the cavity to be able to get underneath them with a torch. On a hot plate, I warmed up some pure Canola oil to 140F for quenching, using a kitchen thermometer to follow the oil temperature.  I didn’t need a huge container for the oil since the parts are generally small and will be quenched one at a time. I put this all together outside, anticipating great eruptions of smoke and flaming oil, and had a fire extinguisher at the ready. In fact, there was only a little smoke and a tiny bit of flame on the larger parts. You could probably do this indoors if you have very good ventilation and a sympathetic spouse.





I heated up the parts with a MAPP torch inside the little brick chamber until they were uniformly glowing bright orange, then quickly grabbed them with tongs and immersed them into the warm canola oil bath, swirling them back and forth in the oil for ten or twenty seconds.
 
Another thing that may help you determine appropriate heat is the use of a small magnet. When the steel is hot enough for quenching, a magnet will no longer be attracted to its surface. I happen to have a little magnet on the non-pointy end of a scriber, and tried this technique on a couple of parts. It does show you when the metal gets to quench temp, but I found it very cumbersome to use a torch in one hand and a magnet in the other on a loose part inside a small cavity. At the end of the day, I just heated everything bright orange and quenched.

(That big round thing in the picture is a wheel for a wheel lock, not part of the Dolep set.)

Dry the oil off the parts and test for hardness now. If the parts are hard, a file should skate over the surface of the part without cutting into the metal. There will be some burnt oil residue on the parts, and the file will take this off, but should otherwise not show an inclination to cut any grooves into your parts. These parts are very brittle at this stage, so be careful not to drop or strike them.

My results were mixed.  I appeared to have nice hard surfaces on my springs, sear, and tumbler, but my frizzen could still be easily cut with a file, and striking the frizzen face with a piece of flint resulted in a dent but no sparks.  I repeated the whole process on the frizzen without much more success. (I posted this whole experience on the ALR forum under this topic: “Frizzen not hardening?” http://americanlongrifles.org/forum/index.php?topic=41457.0  Lots of people had input on this).
 
To make a long saga short, I ended up cleaning up the face of the frizzen with the curved end of a belt sander and case hardened the frizzen using Cherry Red carbonizing compound. This is similar to the old Kasenit and used in the same way. Brownell’s also sells a similar product called “surface hardening compound”.

The Cherry Red comes as a gray powder in a can. I poured a liberal little pile into about a 4” diameter metal lid and heated up the cleaned-up frizzen in my little brick furnace to bright orange again, focusing the heat on the frizzen face. The hot frizzen face was then immediately pushed into the pile of carbonizing compound and allowed to cool. Some of the compound went onto the front (decorated) surface of the frizzen as well, but this is okay. I didn’t try to case harden the stem, toe, or pivot hole of the frizzen. These areas are small and a little fragile and should not be made too brittle, risking fractures.

After the carbonizing compound is cooled it looks like a bubbly cake of gray cooled lava. It will be firm to touch and adherent to the metal. Take the frizzen and caked up carbonizing compound back to the oven and heat it all bright orange again with the torch. The compound should glow as brightly as the steel.  Keep it orange-hot for a bit to allow the carbon to soak into the steel.  The Cherry Red compound calls for a quench in water rather than oil. The bright orange mass of frizzen and Cherry Red was plunged into lukewarm water, accompanied by a sickening “crack” sound.  It was okay, that snapping sound was just the Cherry Red exploding off the surface of the frizzen.
 
In order to get good deep even penetration of carbon into the frizzen face, I repeated this process three times in a row.  After allowing the frizzen to cool off, the frizzen face appeared hard, couldn’t be cut with a file, and striking it with a flint produced some pretty sparks and no big dents!

This process could be repeated at a later date if the frizzen face becomes worn.

TEMPERING:

All the hardened parts are tempered at specific temperatures to draw out a varying degree of hardness. I did this in my digitally controlled oven/kiln. The frizzen needs the least tempering, heating to 375F and holding that temperature for twenty or thirty minutes, then air-cooling. The tumbler and sear are tempered to 575F for the same period of time, and again air-cooled. (They came out of the cooker a very pretty royal blue color. I was sort of sad to polish them back to the white.)  You could probably do the frizzen tempering in your kitchen oven, and possibly also the tumbler and sear, if your kitchen stove can accurately heat up to 575F.

The springs need to be tempered to 750F, and your kitchen stove probably won’t handle this.  Some people temper springs with a torch, heating the polished spring to the aforementioned royal blue color, but no further. The recommended 750F is probably much hotter than this, but you could give it a try. Other folks describe placing the hardened spring in a can under a covering of light motor oil, heating the can until the oil ignites and burns and eventually burns itself out. I’ve never tried this myself, but go for it if you like!

These temperatures I quoted above came from Jim Kibler and I believe are the recommendations of his foundry, based on the steels they use.

After tempering the springs, they might look a little black and crusty. This can be polished off to a smooth bright surface.
 
We’re getting close to final assembly now!  In my next installment:

SNAP! SPRING DISASTERS AND FIXES

Stay tuned!

Gregg

[Hemo]

DOLEP LOCK ASSEMBLY TUTORIAL #6

Back again! Before I launch into my highly anticipated topic of "SPRING DISASTERS", I want to make a brief detour to touch on another task that happened about this time, namely cleanup and polishing of the tumbler and sear.



When last visited, the tumbler and sear were installed, but pretty rough. The sear tip was to fat to firmly catch in the half-cock notch , and the bearing surfaces were just rough in general. I cleaned up the half cock notch by deepening it with a jeweler's file and the small tapered screw slot file. I skinnied the nose of the sear with fine cut half-round needle files and polished and squared the sear nose and full-cock notch with hard stones. The sear would hold nicely in the half-cock notch now, but tended to fall into this notch when released from the full-cock position (there is no fly in this lock to prevent this). I reduced or eliminated this problem by filing down the outer curved surface of the tumbler creating a smooth ramp passing into the superficial part of the half cock notch. (Make any sense?)

BACK TO SPRINGS:

To keep a long story short, two of my recently tempered springs broke, first the mainspring, then the frizzen spring. The sear spring appeared to come out okay. I'll talk about the one successful one first.

When you install the sear spring and sear together, you may find that the upper leaf of the spring is too long and collides with the sear. If so, you should carefully file or grind a little off the tip of this leaf until it lies right at the junction of the round and flat parts on the upper surface of the sear. Having done this, I found it was still very stiff and hard to push the sear up, so I reduced the thickness of the upper leaf of the sear spring by grinding and polishing, taking off most of the thckness at the tip end. I took from one half to two thirds of the thickness off the upper leaf, which it was much easier to move the sear.

When grinding a little spring like this, beware of overheating the spring and killing the temper. Hold the spring in your bare fingers and back off and immediately dip in water if you feel it getting too hot or start to discolor.

ON TO THE DISASTERS:
 
At first, when I mounted my frizzen spring and frizzen, using compression from a mainspring vise, it looked like it was going to be okay except for being extremely stiff and requiring a pretty strong push to flip the frizzen open. I took the frizzen spring out and reduced a lot of the thickness of the upper leaf by grinding and polishing, especially at the tip end of of the leaf, just as described above with the sear spring. It functioned more smoothly after this.

When I started to install the mainspring, slowly applying pressure with a mainspring vise...




...there was a sudden "ping" and I had more pieces than I started with.

After recovering from a momentary cardiac arrest, I collected myself and considered my options. The Dolep lock is no longer advertised on Jim Kibler's web store, and replacement castings, I feared, may be nonexistant. Grasping for any straw, I went through my spare parts pile and found an unused large Siler mainspring, already tempered, and very close in size to the Dolep spring.

The retention stud on the Siler spring is in a completely different location, and there is no mainspring screw. After determining where the Siler spring stud should go on the plate, I drilled a blind hole at this site and used a graver to cut a little notch on the bottom surface of the lockplate bolster to engage the upper leaf of the Siler spring to keep it flat against the plate (as on a regular Siler lock).





After some filing of the Siler spring, especially at the claw tip near the tumbler for clearance, I was able to jimmy the thing into place. Just to show it can be done, here are two pictures (above) showing the spring at full rest and full cock. The spring felt nice and strong, with snappy action, and I believe it would have worked. As it turned out, I was able to get an original Dolep mainspring casting and didn't have to use the replacement Siler. (Read on!)

I needed to do more finishing on the frizzen and put my spring vise on the frizzen spring to remove it...



...when this happened. The frizzen spring must have been very brittle, because the shock of the break simultaneously broke the finial in two places. I found the threaded bulb part of the finial, but the little leafy tip was launched forever into the land of the lost.

Looking through my spare parts pile, I found nothing I could use for a replacement. I took the fractured pieces of the frizzen spring and overlaid them on the full-sized lock pictures in the TOW catalog. It looked like the L&R Manton frizzen spring was a close match, and I ordered one. (EDIT: Actually it was a Durs Egg spring, though Bob Roller tells me these are one and the same.)



I found the L&R frizzen spring was indeed a very close match and even the stud and screw hole were in almost identical positions to the Dolep lock. It has a little hump on the upper leaf to engage the frizzen cam which would have needed filing off. I believe this spring would be a suitable replacement for the Dolep frizzen spring if necessary, but I didn't have to use either the L&R or Siler springs because...





... I was eventually able to reach Jim Kibler after some telephone tag,  and he had extra spring castings! He sent me not one but two of each of the castings for no charge! (Believe me, I was singing "Jim Dandy to the Rescue" after that call!)

The pictures above show the raw and finished spring castings. Note that the unfinished mainspring has some extra metal bulging between the leaves right at the "V". This was present on both castings. This needs to be cleaned out. I used a hacksaw and a jeweler's saw to do this. Be sure not to cut any notches in the spring with your saw, as this is a setup for a spring fracture.

Both new spring castings were filed to shape, polished, and drilled as before without mishap. The process went quicker the second time, having done it once before.

Since I had less than great results with my previous hardening and tempering routine, I decided to pull out the stops and heat treat these springs with an acetylene torch and quench them in brine. I heated both springs to a very bright orange evenly through out the spring and immediately plunged them into brine (room temperature tapwater and table salt poured in until it precipitated.) No cracks or fractures resulted, and they were both quite hard. I popped them into my oven and tempered them to 750F for about 20 minutes. After cooling, it was obvious I had some real springs.

After a little polishing, I was able to install both springs without mishap using a spring vise. I put a flint in the cock and gave it a try. There was a puny spark, and the frizzen was not knocked fully open. Consequently, I had to do a little more shaping and bending, as the mainspring was too weak and the frizzen too strong.

I ground and polished the frizzen spring a little thinner and smoother, and used the acetylene torch to take a little of the bend out of the upper leaf of the frizzen spring along its length. I did the opposite on the mainspring, heating the lower leaf with the torch and gently increasing its curvature to provide more force. After heating and bending the springs, they had to be re-hardened and re-tempered using the same acetylene/brine technique. This went fine.

If you look at the difference between the pictures of the raw castings and finished springs (above), you can see the fairly small changes in curvature I made, but this was enough to balance the springs and make the lock spark like a champ pretty consistently!



That's about all there is to this project except for a few more engraving and polishing details. I'll wrap this all up in my next and probably final installment.

Best wishes to all!

Gregg

[Hemo]

DOLEP LOCK ASSEMBLY TUTORIAL #7

Back again with the final installment of this tutorial. This is a short one, just tying up some loose ends.

FINAL FINISHING:

Just to reiterate what I said on a previous entry on lock finishing, this is a link to Acer's excellent tutorial on this subject. I can't add much more to this:

http://americanlongrifles.org/forum/index.php?topic=2585.0





The cock is a little challenging to finish since it's a complex shape made up almost entirely of curved surfaces. I screwed it into a piece of scrap wood, the flat stop in the inside of the cock firmly against the edge of the wood to keep it from rotating. Holding the wood scrap or clamping it is a vise is a lot easier than trying to hold the casting itself, especially during engraving. As I talked about before regarding decorative engraving of the frizzen, I made the decision to engrave just a single decorative line between the outer border and the cock screw rather than the very fine double line faintly visible on the casting. I found it difficult enough to engrave just this single line around a totally curving surface, let alone two. I did engrave the little floral design just in front of the cock screw, which is fairly visible on the casting. I also sharpened up the edges of the slightly raised floral design on the outside edge of the gooseneck just below the jaw.

If you look at the inside surface of the cock, you will see what looks like a deep file mark or gouge just above the flat stop. This is actually in the casting, and can be seen on the original Dolep lock. I didn't try to file or grind this all the way out, since there is already very little metal contact between the cock and the lock plate, and you definitely don't want the cock to fall off the edge of the plate at full rest. This little defect probably won't show after the lock is mounted. If you are compulsive or paranoid, you could even add a little metal to the inner surface of the lock, if you have access to a TIG welder or the like, to create a little more contact with the lock plate. (I didn't.)

Dave (Smart Dog) Person says he recommends casehardening the cock and plate to avoid peening the metal where the cock hits the plate. Jim Kibler says this is not necessary. There is always some risk of warping your finished pieces by case hardening. I haven't done it. Your choice!



FINISHING SCREWS:

The picture above shows the technique of shaping the cock jaw screw in a high speed drill press using a half round file. Triangular files and flats can be used to create bands and rings. All the internal and external screws on the original lock had rounded polished heads with "V" screw slots. Small screw heads can be done the same way as above, with the screw head right up against the chuck. Screw heads can be polished to a bright finish by applying firm pressure while spinning with 220-600 grit sandpaper, after cutting the slots.

Again, if you're really compulsive and want to prevent buggering the screw slots, you could harden them all by heating red-orange and quenching, followed by tempering to a nice royal blue color. (I didn't do this either.)

POLISHING THE PLATE:





In the first picture above, I show the use of my cheapest tool (a big cut-off nail with a rectangle of 400 grit sandpaper taped to the nail and wrapped clockwise) mounted in my little high speed drill press to polish up the surface of the pan. As I described before, this little device can also be used to polish up the inside curve of a gooseneck cock, the inner curved surface of a mainspring claw, or the bearing surface of the toe of the tumbler. You can also use it to polish springs, but it's very easy to leave ripples or dips on flat surfaces.

For smooth function of the lock it's important to have a polished flat surface on the inside of the lock plate. My previous photos of my lock plate have shown a lot of file marks. The second picture above shows a 2 x 6 x 1/2" 600 grit diamond block designed for sharpening gravers. I got this block from Lindsay engraver's supply. This block is very flat and hard and can be used to clean up the tool marks on the lock plate, bolster, and upper surface of the pan. I plan to do a little more polishing on the plate surface with pumice on piece of leather. Light buffing on a wheel would also be in order.

ONE LAST USEFUL THING TO HAVE...



...that I neglected to mention in my first post on materials needed is a set of fractional drillbits. In my previous posts I have described the use of both wire gauge drillbits and fractional drillbits.
I know some of the fractional sizes sound sort of oddball, but they were all in this little drill register set that I bought many years ago for under $20. I've replaced several of these drill bits, one by one, as I have worn them out or broken them.

ENGRAVING RESOURCES:






It's well beyond the scope of this tutorial to try to teach engraving. Several DVD's are out there, as shown, which are useful. Meek's book on engraving is an old one and has good sections on graver sharpening and use, though much of the book is probably not applicable to historic arms making. Schipper's book is newer and has good illustrations on sharpening and engraving tecniques. He shows lots of his engraving work on contemporary muzzleloaders, but I personally think his work is a little too sophisticated and over-the-top to apply to historic reproductions, especially early American pieces.

Far and away the best resources to use to learn engraving are courses taught by the experts. I have attended engraving courses over the years at the NMLRA gunmaking seminars at Western Kentucky University taught by Lynton McKenzie and John Bivins in the '80's and more recently by Jim Kibler and Wallace Gusler. One-on-one instruction such as this, plus lots of practice, are the best ways to pick up engraving skills.

Well, folks, I think that wraps it up!

This turned out to be a much more lengthy tutorial than I expected, but I was encouraged not to pull any punches, so I didn't.

I hope some folks have found this all helpful! Thanks to all who have stuck with me through this series. Feedback is always welcome!

Best to all,

Gregg