Can I tap my barrel for a breech plug, or do I need to use a lathe?

[T*O*F]

what are you using to clamp your barrel?

I fasten a milling machine vise to the drill table.  I also have lead liners which I made by pouring lead into a flat tin and then put a 90 degree bend in.  Also, the movable jaw of the vise will pivot enough to clamp slightly tapered objects.

[Mark Elliott]

Does anyone have photos of the period tools for drilling and taping the breech?   It seems to me that the period approach would be the simplest and easiest without a lathe or power tools.    Personally,   I would feel better using a piloted drill and tap with a hand drill or brace than trying to clamp a barrel to a drill press table. 

[bob in the woods]

The first barrel I breached was a brass pistol barrel, and it was done with a brace. After watching the "Gunsmith of Williamsburg" video, I just went ahead and did it. Slow is not always a bad thing. It all went fine. 

[bob in the woods]

I should also say that I have the Pioneer Video re Mike Miller finishing up the hand forged barrel that was done by Jon Labauch and son along with Mike.   Mike draw files the barrel, files out the forged breach plug and threads it, as well as drilling and tapping the breach.  This is the stuff that really interests me. Since I don't do this for a living, the time it takes is not an issue   As long as the end result is safe.

[James Wilson Everett]

Guys,

The period tools look like this, first the breech grinder that opens the hole up to the size for the threading.  A regular spade drill bit does not work well here for two reasons.  First, the large diameter is nearly impossible to drill with a spade bit & hand brace, especially for an old guy like me, it takes way too much force.  Second, an 18th c spade bit will not drill to an accurate diameter.  The breech grinder will cut to a controlled diameter and stay aligned with the barrel bore with the pilot.  I use only two diameters of breech plug threads, so two breech grinders.







The 18th c breech taps were in sets of three.  The starting tap was piloted to start the threads on center, the second tap was tapered and the third tap was straight.  When using these taps the metal is not cut, there are no cutting chips.  The metal, wrought iron, is cold swaged into the thread form.  These are a good bit easier to use than modern thread cutting taps.  Here are two original sets.





Here is a closeup of a starting tap with the pilot.

[whetrock]

For those interested in traditional technology, here’s a list that might be helpful. Sorry, the photos and diagrams are all copyrighted, so I can’t just scan and post them. I’ll just give you a description. You can then decide if you want to find a copy to review for yourself.

Diagram of a breeching reamer with pilot.
(Stelle and Harrison. The Gunsmith’s Manual. page 165.)
The diagram shows a reamer with a solid pilot (no bushing). The texts state that the pilot should fit the bore (and it also notes that if it does not fit but is close, that paper can be wrapped around it to make it fit better). The reamer has four end-cutting mill teeth and four spiral flutes (with a very slow twist), which the text explains are necessary for carrying away chips. The text describes how to make this tool, and notes that the smith will need to “turn them to the size and shape” required. That is to say that they suggest using a lathe to make the blank from which the reamers teeth and flutes are then filed. It suggests that the pilot may be “about an inch”. (The diagram shows the pilot that is in length about 1.5 times the diameter of the reamer. I mention that for the reason that I think the proportional dimension is more relevant than the actual length.) The diagram does not show the shape of the shank.

Photo of a breeching reamer with pilot.
(Dillin. The Kentucky Rifle. Page 64)
Item #2 in the photos for tools on page 64 shows a fluted reamer, simply described as a tool “for preparing the breech for the threading tool”. It has straight (not twisted) flutes. The pilot has no bushing, and its length seems to be about 2 times the diameter of the reamer. The shank of this tool looks to be four-sided and tapered, suggesting that it would be fitted to a brace with a tapered-hole lantern.

Diagram of a breeching tap with pilot.
(Stelle and Harrison. The Gunsmith’s Manual. page 167.)
The diagram shows a fluted tap with a solid pilot (no bushing). I find it difficult to interpret from the rakes on the flutes whether this is describing a cutting tap or a swage-type tap (jam/jamb tap). I find the text to be similarly confusing on this point. Granted, the text uses the word “cut”, but that does not necessarily mean that they are describing a cutting tap. The pilot seems to be about 2 times the diameter of the tap. The shank of this tool shows a short, even sided head (probably four sided). Note that their diagram shows only one of two taps. The text describes two taps. It reads:

QUOTE:  "(page 167) Breeching taps should be made in pairs, one tapered a little and its mate made straight and with a full thread, so as to cut full at the bottom where the thread terminates. If the first tap be not tapered a little, the thread should be nearly all removed at the end, and gradually increased for five or six threads, (page 168) when it will be full size. A stem or projection is made as shown in the cut, Fig. 36, which enters and fills the bore of the gun and so serves to insure a thread straight with the barrel. If the bore be larger than the extension, slip over it a piece of brass tube or ferrule of some kind, until it fits a little snug in the bore. If but little be wanting to make the fit, a piece of writing paper or a bit of card may be wrapped around it. Old-fashioned gunsmiths have been known to wind tow around an extension to make a fit."

The text then offers additional comment about the recommended length of "extensions" (pilots) for various types of firearms (because of different bore sizes?), etc.

Photo of a breeching tap with pilot.
(Dillin. The Kentucky Rifle. Page 64)
Item #1 in the photos for tools on page 64 shows a breeching tap, simply described as a tool “for threading the barrel for the breech plug”. The photo is small and dark, but it seems to be of a similar type to that described in Stelle and Harrison, p 167. The pilot has no bushing, and its length seems to be about 1.75 times the diameter of the tap. The photo does not show how the shank is shaped, but instead shows it mounted in some sort of handle (of which only a small portion is shown).

Diagram of a mill cutter with a bushed pilot.
(Stelle and Harrison. The Gunsmith’s Manual. page 170-172.)
The diagrams on page 170-171 show three different mill-head cutters, each with a bushed pilot. These mill head cutters do not have flutes. The text explains that these tools are designed to cut the recess for the head of a breech loading cartridge. The text suggests a brass bushing, and a neck (or narrow section) is provided between the bushing and the cutter. The brass ferrules are press fitted and turned to size in place (that is to say that the bushing does not spin). The text explains that this small neck is provided as a place to catch chips. The text suggests that eight teeth are sufficient. The text also recommends against using drills or four-fluted reamers for this job, stating that they do not provide as good a result as do these mill-head cutters for this job that requires a perfectly concentric, well finished face.
(These cutters diagram look much like the mill head cutter with a brass bushing in Jim’s photo.)

Photo of an assortment of handmade taps
(Irwin. Guns and gunmaking tools of Southern Appalachia. Page 55)
The photo shows tools that had been used by Appalachian smiths of the Howell family. The photo shows an assortment of thirteen taps, several simple screw plates and two tap handles. The taps are not organized into sets, as are those in Jim’s photos. However, it is noteworthy that several are of the tapered type. The larger examples clearly show the hand-filed flute, similar to those in Jim’s photos. All of these taps are made from hand-forged blanks, with shanks very similar to those in Jim’s photos.

That's all the documentation I’ve found thus far on this topic. I think we can assume that most of these tools were used on iron (not steel) barrels. And there are important differences in the technology required for those types of metals. As Jim has explained in a different thread when describing how to use a swage tool to make iron screws, swaged threads are stronger that cut threads when using iron that has inclusions in it.
Steel barrels are generally too hard to be effectively tapped with swage taps anyway. Cutting taps for steel barrels. Swage taps for iron barrels. That's how I understand it, anyway.

[whetrock]

Let me add another comment, again for the benefit of those of us interested in old technology.

As Dan mentioned, and as the Stelle and Harrison book also mentioned, it is best if some of these tools be "turned" so as to get them on center.

But lest we get confused by the mixed discussion of both modern and antique technology, I want to point out that in the old days, a lathe was not a high powered tool like we think of today. John Wyke’s 18th c. pattern book "A Catalogue of Tools for Watch and Clock Makers" shows two hand powered lathes, which were built and sold as complete units. These were belt driven by large, hand-cranked wheels (similar to a wooden spinning wheel). It also shows a wide assortment of smaller “turns” (small, dead center lathes) that fit in vises and for which the stock was turned by a horse-hair bow (similar to a bow drill). The same catalogue also shows a very nice small lathe designed for drilling holes, also driven by a horse-hair bow. In modern terms, we would think of this small lathe as a horizontal drill press.

A tool that is chucked between two dead centers can be filed and polished into a cylinder, even at hand-powered speeds, especially if accelerated by a bow or a belt-driven, hand-cranked wheel.

As for drills and reamers that will be turned in a brace by hand power (approx 60 rpm), it should be understood that such tools don’t require the same level of precision in manufacture that is required of a tool that will be chucked in a modern lathe and turned at 1000 rpm. A tool that is reasonably centered, reasonably balanced, and which has a pilot, will indeed cut a circle, even if turned by hand. Thus we see old drills that still have rough hammered shanks that were never cleaned up, never turned. It was not necessary that they be perfectly balanced.

[Mark Elliott]

Jim,

Thanks for the photos.   That is exactly what I had envisioned. 

[David R. Pennington]

This has developed into a very interesting thread. Thanks guys. This is the kind of stuff I really enjoy learning about.

[whetrock]

Yes, the photos are terrific, Jim. Really helpful.

Do you own these taps? If so, could you tell us something about the flutes filed into the second and third, especially the third (cylindrical) bottoming tap? Any chance we could get you to post a picture of the end of that tap, so that we can see how the flute was filed?

I was also wondering if you could give some info about the relationship between hole and tap size. For a given final tap size, how big should the initial hole be made?  (I would expect to do some trial runs before committing to a barrel, of course.)




PS: I cleaned up a bunch of typos in the stuff I posted above. Hope that helps a bit.

[James Wilson Everett]

Pete,

Your observations are correct.  When using the 18th c type taps in wrought iron the threads "grow" when swaged, both the male & female sides of the joint.  One figure that I remember is that for the smaller lockplate screws the male side screw shaft is formed to a diameter of 0.152, after swaging the threads the diameter grows to 0.174, percentage wise quite a lot.  I have not measured the growth of the female side, but I feel sure that they also act in a similar manner that the inside diameter is much smaller after threading.  The difficult thing is this - for anyone who really wants to make an 18th c gun - what is are the proper diameters of the screw shaft and the screw hole to be before swaging the threads?  Certainly there is no reference or manual to tell you the size, they must be discovered by trial & error!  Today to make a #10 screw we form the shaft to a diameter of 0.190, then cut the threads, just like the machinist's Handbook says.  In the 18th c the gunsmith would fiddle and figure with his screwplate until he got a combination that worked. 

I have figured this out for the few screw sizes I use in making guns, but surely not on the first try!  Here is a gauge that I use to get the proper size female hole for a lockplate screw, 0.174 - 30.  You can see the go - nogo sizes on the shaft.  When the hole is the proper size, the gauge will slide through the hole halfway.  For the breech plug hole the grinder will give the proper size, but again it took a lot of trial - error.



As for the flutes filed into the taps, they do have a bias to somewhat act as a cutting edge.  I think that you can see this in the photos.  However, when using such taps there are no cutting chips, only a little metal "dust" so the flutes are not cutting, they just give a little space for the collection of the "dust".

I do own these gunsmith taps and a lot of other 18th c gunsmith tools.  One interesting tap that is 19th c is a breechplug tap that also has cutting teeth on the front face.  If you ever wished to have the breech hole a little deeper so the breechplug will turn to the right flat, here is the tool for you.  I think that on this tool you can better see the flutes, on this tool it does look like the tap will actually cut rather than swage.

Don't you wish there old tools could talk?

[U



Jim

[Jim Kibler]

Don't think it's reasonable to think the end of that tap is going to bore the shoulder any deeper while threads are engaged.  All it will do is screw in and cause the cutters to dig in and that's it.  I would assume they just used the front of the tap for chamfering other smaller holes.

[Acer Saccharum]

Kibler, you are spot on with your assessment. It's a multi-function tool. 

[Long John]

docone,

I have done a couple of times and it worked just fine.  Here's what I did.

I took a standard HSS taper tap of the correct thread and put it in the fire place one evening.  Next morning I had an annealed tap.  I then chucked it into my drill press and held a file against the side and filed off the bottom half of the threads and shaft diameter down until it was a snug fit into the muzzle.  I then used the grinder to put a little relief on the cutting threads, hardened and tempered the tap (light oil quench, tempered at dark straw color).  Now I had a tap that has a pilot that lines it up with the bore.  I then was able to tap the threads to receive the breechplug.  I don't worry about the use of a bottoming tap.  I just file down the first 1.5 threads of the breech plug to the minor diameter of the threads.  Then I polish the face, soot it up and run it in to assess the seal much as Dan has described.

Best Regards,

John Cholin

[Curtis]

Excellent Idea, Long John!

Curtis

[Mark Elliott]

I think what I am going to do about the taps is take my current taper taps, anneal them, and then drill and tap a hole in the center for a screw to hold a brass pilot just like the boring tool Jim showed.   I plan to make two of the boring tools just like Jim's.   I can then share the brass pilots between the boring tool and the taps.   It isn't exactly historically correct, but I think it is close enough and should be quick and easy to do.

[bob in the woods]

That is a brilliant idea !  Wish I thought of it, But now that you have…I can rest my brain 
Thanks for sharing.

[Acer Saccharum]

HSS taps won't anneal without heat treat ovens and science.

High Carbon taps you can anneal at home, and re-harden.

[Long John]

Acer,

Thank you for your input. I ASSUMED the tap was HSS as I know it wasn't carbide, nitride coated or something else special.  It was the cheapest 5/8-18 tap I could find.  I think I got it from Grainger.  This was years ago.  But the process I used is accurately described above.  But your point is extremely valuable - if I were to try this again and got a HSS tap it wouldn't work.  I was just fat-butt lucky!

I guess some times its better to be lucky than good.

Best Regards,

John Cholin

[Acer Saccharum]

HSS steel can cut metal at red heat, and still maintain hardness. Carbon steel, once it gets past 350-450 deg, will lose its temper.

[Mark Elliott]

My taps for breeches are carbon steel.

[Jim Kibler]

Rather than trying to tap a tap for a guide, I would think it much better to turn down an annealed tap to say .375" then make a series of bushings that can be snugly inserted into the bore to accept it.  Bushings made of brass or bronze would probably be best. 

[Bob Roller]

My experience with "High Speed"end mills says they fail rapidly after they start to turn blue
And I want no more of them. The 8%cobalt seems better and carbide not that n=much better.
NONE of them are "OD'D" as they come from the industrial suppliers and smooth finishes are
not expected unless the can be reground before using.These are new end mills and none are worth
a dime.I used to work in a cutter grinder shop and we would get new mills and the orders were to
OD* them by locating the lowest flute and grinding the other three to that non specific dimension.
This junk coming in from China should be sent back and I always ask for the country of origin.

Bob Roller

OD* means outside diameter.

[Mark Elliott]

The reason I wanted to tap a tap for screw is that it was must less machining than turning the tap down.   If you turn the tap down to form a pilot, then you have to reshape the flutes on the tap, and that means setting the lathe for taper turning.   That is a real pain on my lathe.   So,  to me, drilling and taping a hole is a lot less trouble.   Given the size of the taps we are talking about; 5/8" and 3/4"'; there is plenty of meat to accomodate a large screw.   I would use a #10 lock bolt, because I have plenty of them and can thread them to the length of the bushing i choose to make.  Making the bushings is all the same no matter which way you go.     

[Mark Elliott]

On second thought,  I would want to use a larger screw than #10.    I guess I would make one.  It is still less work than completely reshaping a tap.