Bare Bones AWI Period Southern Rifle

[Artificer]

It depends on whether your tumbler reamer makes a hole bigger than the tumbler you are trying to replace, doesn't it? Unless you are going to make a new mill, the diameter of the tumbler bearings is a fixed point. I was assuming that the tumbler mill on hand was no larger than that of the original tumbler, which I suppose isn't likely to have always been the case. Good point about the spot annealing, though if you have to reharden anyway I'm not sure that it would save much time.

Mike Miller reams his holes from both sides to fit the tumbler shaft, IIRC. Not having worked with 18th century tools to make a lock, I was just assuming that was the right way to do it. The possibility that you could just ream from the inside and taper the tumbler shafts to match it didn't occur to me. I don't see how the bearings on the tumbler could have come tapered from the mill, though - Unless I've missed something major the whole point of a tumbler mill is to grind away everything from the side of the tumbler that isn't a bearing, and there are no teeth in the holes. Now, you might taper the rough blank to get what will eventually become a bearing started, but isn't that part cut away?

Gunsmiths in the colonies made their own Tumbler Mills and would have had at least four to six sets/sizes of clearance holes for the arbors in each Mill. This is because they had to repair anything from small pistol locks to large fowlers and even military muskets in some cases. So when they needed a Tumbler with larger diameter arbors, they just went up to the next size larger set of holes compared to the Tumbler they were replacing or they made a new Mill. These Tumbler mills were not as fancy as would have been found in the larger Lock Making Shops in England or Europe.

Are you sure Mr. Miller reams from both sides of each hole or is he just chamfering the outer edge of the outside of the hole, so as not to leave a sharp edge? I don't believe they reamed from both sides as that would leave only a small ledge in the center of the hole around the diameter and that would wear out quickly. Instead, by reaming on just one side, there is a flat edge going around the diameter, though slightly angled. Of course the sharp edge on both sides of all holes in the lock plate were chamfered so as not to leave sharp edges.

Making a new square reamer would not have been difficult OR they could have used paper shims to slightly increase the cutting diameter of the reamer they had, basically the same technology they used to ream the bore of the gun.

OK, as forged, the arbors/pivot points were tapered and then filed to fit into the holes in the Tumbler Mill. The holes in the Tumbler Mills did not have a way to cut the arbors round and perpendicular to the flat edges the Mill cut on the body of the Tumbler, as you mentioned. That would still leave the arbors/pivot points a bit oversize to be fitted to the holes in the lock plate and in the bridle. The arbor on the side of the tumbler that goes through the lock plate was left oversize both in diameter and in length, so it could be held in the vise while the flat faces of the tumbler were cut by the Mill and later to be held in the vise while the four square flats were filed to fit the square hole in the ****. Once the square was filed on the end, then it would have been cut off and drilled/tapped for the **** Screw.

Fitting was no doubt done with lamp black to show where the high spots were to file down in all stages of the work.

So the arbor points would be slightly tapered to match the slightly tapered holes, as Rich Pierce mentioned.


I would MUCH rather spot anneal the plate to enlarge the Tumbler hole than soften the entire plate and risk warpage that would throw off kilter the other holes in the plate and thus throw off the fit of the bridle, especially. Then when the plate was rehardened, one could use the threaded holes with longer machine thread screws to bolt through another piece of Iron onto the plate to keep the plate flat and as much as possible in the same position after hardening.

Not sure if I answered everything as we kind of jumped around?

By the way, the techniques I describe come from the JHAT series, examining parts in original locks and from my own experience in precision hand filing parts.

Gus

 

[Loyalist Dave]

What still surprises me a little is how LATE in the 18th century they were still using locks with no bridle on the pan

Yeah me too...

I was originally taught that such unbridled pans were not seen on rifles past 1790..., so IF you found a rifle dated after that with such a lock, it was a reused lock.

THEN I found out that no, less expensive locks were available without bridled pans, and trade rifles were often seen with them, made after 1810 even, and of course we have the 1830 example posted earlier in this thread as well.



LD