left-handed Alex Henry/Stanton/Bob Roller lock. Part4. The sear and searspring.

[Rolf]

The sear spring.
I know, I could have saved time by bending thin spring stock to make the sear spring. But I think milled springs look nicer.

Locating the screw hole for the sear on the lock plate.
This hole is between the second and third bridle posts, as close to the third as possible. Mount the bridle on the plate. Make a mockup of the sear spring and super glue to plate, touching the third post.


 In this picture, the bridle is removed.


Drill and tap for a #4-40 screw.Mill out the slot for the tab with a 1,5mm endmill.


The sear spring blanks are cut from 1075 sheet stock 4,7mm thick (0.187”) and are 6mm x55mm. The hole for the spring screw is 3,1mm and drilled through the 4,7mm sides, not the 6mm sides.


Next, I milled out the shoulder for the screw head.


Check the height of the blank. It should be as tall as possible, but still slip under the bridle. If to tall, take a little off the bottom.


Mount the blank on the plate and mark where the tab should be.


Mill out the tab oversized. It’s easier to mount the blank level in the mill before thinning the spring blade.


Take a piece of square stock and mill a 1,4mm deep shelf.

 
Solder the blank to the shelf. Check against the lock plate to insure it’s correctly orientated before milling the spring blade down to 1,5 mm.


Heat, remove blank, clean off solder. File a taper from the end of the blank to the beginning of the tab. The blank tapers down to 0.8mm. File out the screw hole eye.


Mount the blank on the lock plate with the tumbler. Mark of on the top side of the blank a spot that’s 2-3mm from edge of the lock plate.  This is where the spring will be bent. Mount the tumbler and hammer. The tumbler hits the sear screw and stops the hammer before reaching the fired position.


File down the rear of the tumbler until the hammer can be rotated to the fired position. It’s now the sear screw that stops the hammers movement.


Heat and bend the spring blank, open the arms so the lower arm passes a 1/6 “below the sear axel hole in the plate. Harden and temper the spring. I temper for 10minutes at 370 Celsius in an oven. Do not cut to length before the sear is made (forgot to take a picture).


The sear
Make a sear pattern out of brass. Make sure there is enough room between the sear arm and the third bridle post for the spring to work.


The sear is made from 6mm thick mild steel. Glue the pattern on, paint with dykem, drill out, file clean. Make sure the sear slips under bridle. At this stage the sear arm is not bent.


Take off the bridle, mount the sear spring with an extra long screw. Cut the length of sear spring so it presses down on the front end of the sear arm. Remove all parts from lock plate.


Putting it all together again.
Mount the frizzen spring on the plate. Do not put the tab in the slot.


Mount the sear and the tumbler. Keep the spring tab out of the slot.


Mount the bridle on the sear axel and the tumbler axel. Make sure the spring is between the third and fourth bridle post before pushing it all the way down. If the spring tab is in the slot, the spring will push the sear axel out of alignment and the bridle can’t be mounted on the plate.


Screw down the bridle, push the sear spring so the tab slips in the slot. This is why the sear spring blank must fit under the bridle.


Fitting the tumbler to the sear.
Mount the hammer on the tumbler. Rotate the hammer to the cocked position. That’s when the tumbler arm hits the first bridle post. Scribe the position on the tumbler. Repeat for the half cock position.


Remove the tumbler and start the notches with a #4 blade in a jeweler’s saw. I find this gives me better precision than starting with a file. It’s also easier to keep the notches square.


The notches are cut to the depth of the sear nose and filed to fit the sear with a barrette file.



Bending the sear arm.
The sear arm is 3.5mm thick and 6mm wide. I did a lot of experiments on pieces of steel. It was impossible to get a precise placement of the bend and a sharp 90-degree angle without cutting the arm and welding.

The easiest way to bend the arm is to cut a slot in the arm on the side that lays on the lock plate.
The dept of the slot must be 25% of the thickness(1,5mm) and placed 3mm inside of the edge of the lock plate (will explain later).


Put in a vice, start the bend by heating from the opposite side and tap the arm over. When the slot is opened a bit, heat from the slot side tap all the way over. This avoids tearing the metal.


If the slot is less than 25% of the metal, it will tear, or the arm will not give sharp bend.
If it’s deeper, you will get a larger corner that has to be weld up.

Look at the bend. The metal on the inside corner is compressed and thickened. The metal on the outside is stretched and thinned.


File away the thickened metal. Place in a vice and adjust the angle.


Remove scale from all areas where you what the weld to fuse. This is quickly done with a Dremel with a diamond burr.


If you assemble the lock with the sear in place, you will see the inside corner of the sear elbow is 3,0-3,5 mm inboard the edge of the lock plate and the rest hanging outside the lock plate. The part that’s hanging out will be milled away after welding the sear (sorry forgot to take pictures).

Welding the sear
Welding was done with with a Mig welder. Clamp the sear to a thick piece of brass. Add a large blob of molten metal.


Turn the sear around, clean off scale and weld up the other side.
Sometimes the first attempt does not fill the whole corner. Just clean off the scale , dig out any cold shunts and add a new blob.


File away excess weld.
Mill away the part of the sear arm hanging out the lock plate. Here are pictures of the finished sear.


Sear mounted in the lock.


Next part will be the fly.

Best regards
Rolf

Links to the other parts:
left-handed Alex Henry/Staton/Bob Roller lock. Part 1. Lock plate and Hammer
https://americanlongrifles.org/forum/index.php?topic=73225.0

left-handed Alex Henry/Staton/Bob Roller lock.Part2. Four post bridle and screws
https://americanlongrifles.org/forum/index.php?topic=73497.0

left-handed Alex Henry/Staton/Bob Roller lock. Part3 The tumbler.
https://americanlongrifles.org/forum/index.php?topic=73935.msg736278#msg736278

[J. Talbert]

That some very nice, precise work Rolf.

Hat’s off to you…
Jeff

[Bob Roller]

ONE of these s now more than I want to make and SIX is amazing.I have a semi finished reduced size 4 screw lock partially completed and maybe I'll finish it......maybe.Keep us in the loop on this fascinating project.
Bob Roller

[yellowhousejake]

Forgive my ignorance here, but there is nothing wrong with ignorance right? It just means I do not know.

Isn't it a lot to ask a 4-40 sear screw to arrest the travel of a hammer under the full force of a mainspring? I would think it would damage the sear, sear screw, threads in the plate if it were to happen more than once.

DAve

[Bob Roller]

When this lock(s) is installed in the gun,the nipple will stop the hammer before the tumbler can impact the bridle.Any lock can be ruined
if it is snapped against the bridle and that includes military styles with heavier screws.Some of these English locks when off the gun and
the hammer lowered look like a botched lock making job but when installed in the stock the the mainspring is compressed even when the
hammer is resting on the nipple.When the spring is fully compressed at full cock the speed of the lock is enhanced by a lot.The so called
botched work is the mainspring hanging below the lock plate but that preloads the mainspring.
Bob Roller

[Daryl]

Which is why you never let the hammer down without there being a nipple in the bolster.

[Hank01]

How sweet it is! Thank you for sharing this Rolf. Indeed this is impressive workmanship.

Hank

[yellowhousejake]

Yea, hits the nipple first when installed in the gun, understood that. I only asked because my other locks all stop the hammer when it contacts the plate, if out of the gun. This includes an original Henry lock and a Roller three screw Henry lock.

So I am to understand that the tumbler hitting the sear screw is more of a location point?

Thanks for the answers.

DAve

[yellowhousejake]

I knew what I wrote was incorrect, so I pulled the lock from the Henry and took pics of it and the Roller lock. The Henry tumbler contacts the bridle and not the sear screw at full forward travel. On the Roller three screw, the hammer meets the plate at exactly the same point the tumbler contacts the bridle in full forward travel. The tumbler rotation is not arrested by the hammer contacting the plate, it is the tumbler contacting the bridle at the boss(post) for screw two. I mis-spoke.

The geometry can be tricky and the tolerances are very tight. I know because the Henry lock had a cracked bridle and I had to make another. Neither lock has the tumbler touching the sear screw at any point. I do not know if that matters in the end, the work you are doing Rolf is very well done and this is just another bit of information that might help you.

DAve

[Rolf]

Yellowhousejake, thank you for  the pictures and information.

Had not thought about stopping the tumbler against the second bridle post. I have a original Statton four screw lock. This lock uses the third post to stop the tumbler, put here the spring screw is place behind the third post towards the rear of the lockplate. If you read "part 2. the tumbler", I had filed the tumbler to stop on the third post. When I started on the sear spring, I found out there was not enough room to place the spring screw behind post three. Bob told me the spring screw was placed between post three and two. To do this I had file the tumbler to stop on the spring screw.

I don't think it has any practical consequences wither a bridle post or the sear spring is used as a stop.
All the screws are 4-40 and the spring screw is less than half the length of the bridle screws. It's less prone to bending.
The collar around the sear screw is the same size as the bridle posts and the sear spring is connected to the lock plate  with a tab, and the sear spring is harden and temperd.

I did not want the hammer to hit the lock plate because this can cause peening the lockplate or marring the hammer. Mounted in a gun, it's the percussion nipple that stops the hammer and none of the screws hit.

Best regards
Rolf

[runastav]

Rolf beautiful work as always! Im working on a Left handed Alexsander Henry falling block rifle and  if Dennis allow it I show only  the nice sidelock here!
Runar

[Scota4570]

Beautiful and inspiring work.  I am doing another lock and I see ideas in the photos. 

A question on sears.   At the 90* bend I have been doing it different.   Where the bend needs to be I file a 90* notch in the inside of the bend.  I make the bend hot.  Then I fill the seam with high temp silver solder.  The seam is almost invisible as the part is left white. 

Is there any reason to do or not do it this way?

Yes, I need to get a TIG welder. 

[Jim Kibler]

You might consider just making a sear from maybe 3/8" plate and just cut the bend out.  I think it would probably be easier in the end.

Jim

[Bob Roller]

I made sears from both 3/8 and 7/16 x 1 Flat ground tool steel by making a right angle cut and the finishing on the milling machine to finished dimension which was .232 + or -.003.and then cut to length with with horizontal bandsaw.This material can be hardened in oil like the tumbler which is 1144 that starts as 1.250 diameter so a longer arm can be established for the link to the mainspring.Bench crafted locks IF detailed are a labor intensive thing and now with arthritis in my right shoulder and lower back spams I think I am done.Jim Kibler and CNC has made it possible for fine locks to be sold and at affordable prices.The lock is the heart of the gun and the mechanism behind the plate makes it a usable rifle for hunting or target shooting.
The above mentioned right angle cut was done on a verticlal metal cutting band saw.Paint both sides of the blade after starting it with threading fluid and the job is easier.Thanks to Rolf in far off Norway for starting this interesting thread and that "4 pin"pattern is not the easiest one to make.
Bob Roller

[Rolf]

Beautiful and inspiring work.  I am doing another lock and I see ideas in the photos. 
A question on sears.   At the 90* bend I have been doing it different.   Where the bend needs to be I file a 90* notch in the inside of the bend.  I make the bend hot.  Then I fill the seam with high temp silver solder.  The seam is almost invisible as the part is left white. 

Is there any reason to do or not do it this way?
Yes, I need to get a TIG welder.

I try to avoid soldering lock parts because they can't be case harden. On gun parts that are not going to be case harden, silver solder works great.

Best regards
Rolf

[Rolf]

You might consider just making a sear from maybe 3/8" plate and just cut the bend out.  I think it would probably be easier in the end.

Jim

Thanks for the tip. I'll try that next time, if I can find thick enough steel. Finding thick steel in small quantities in Norway is a big problem. There are suppliers in Norway, but when I try to order, they ask how many tons do I want  .
I used to be able to get scraps from a machine shop nearby, but they went bankrupt last year. The owner of the shop was a gun enthusiast. Most machine shops won't sell scraps, because they regard it as a wast of their time.

Getting steel from american suppliers is possible, but very expensive, due to shipping and custom fees.

I bought 10 lb of 1075 from Jersey Steel Baron this year. The shipping of 1 lb costs almost the same as 10 lb.
The steel cost 107$  = the shipping 160$ = 267$
Add Norwegian custom fees + 25% vat  and you get grand total of 370$ for 107$ worth of steel.

Best regards
Rolf

Ps: I made the sears from 10mm steel that I milled down to 6mm before cutting out the blanks.

[Jim Kibler]

Rolf,

For about any part other than springs and perhaps a frizzen, just use any mild steel available.  Structural steel etc. it doesn’t matter.  Just pack case harden them and you’ll be good.  There should be plenty of mild steel around and available.

[Rolf]

Rolf,
For about any part other than springs and perhaps a frizzen, just use any mild steel available.  Structural steel etc. it doesn’t matter.  Just pack case harden them and you’ll be good.  There should be plenty of mild steel around and available.

That's what I've been doing.
But, due to HSE rules in Norway, scrap yards have been closed to private persons the last 10 years.
I have enough steel for lock plates, bridles and tumblers. I can weld sears.  What I need is to find a solution for the thicker parts like, cocks, hammers, frizzens and pans. I'll find a solution, I don't need much. Don't make that many locks pr year.

Best regards
Rolf

[snapper]

Most Americans have no idea on how good we have it.

Great work!   Looking forward to the completed rifle.

Fleener

[yellowhousejake]

I have had excellent luck using discarded commercial mowing blades. They are high carbon steel, not really needed, but after sitting in the hot wood stove for a cold winter evening you can dig them out of the ash the next morning and they machine quite well.

I have made numerous plates, sears, and bridles from mower blades.

Commercial blades are from 8mm to 15mm thick. Residential blades run from 5mm to 8mm and work well also, though much softer.

DAve

[Bob Roller]

Most Americans have no idea on how good we have it.

Great work!   Looking forward to the completed rifle.

Fleener

As Fleener says,we have it GOOD here in the U S of A and I would call one of many companies and get anything I needed in any quantities needed.Screw material was 12L14.Tumblers 1144.springs 1075 annealed and sears and "flys" were 0-1.5 and 7 flute carbide mills in several sizes and all readily available.Flintlocks were done as follows.
I used available external parts from 2 lock makers that ceased making them,Chet Shoults and Russ Hamm for a long time and the the externals from some of the L&R's.I recovered the actual cost of parts on all these and then charged for the labor on the bench crafted parts,Now the only things I make are triggers and it's been a while since I made any.I refuse to pay for heating the shop so nothing more until warm weather arrives to stay.

Bob Roller