Shaft hole in cock/hammer

[doug]

     Having screwed up on the first try, yet again, I have a question for the builders.  When you are fitting a blank hammer or flint cock to a tumbler shaft, how do you get the correct orientation on the square hole in the hammer?  Ideally the shoulder on the cock stops at the same time as the tumbler comes up against the bridle and the lower jaw is just over the pan.   Since the square shaft is covered by the hammer when it is in place, I can't just trace around the shaft.

thanks Doug

[Roy S.]

what you can do is build up the back of the hammer with soft solder or even epoxy.. then line up the hammer, with the internals in place, and give the hammer a slight tap against the tumbler shaft.  This will show you where the corners of the square go..

[flintriflesmith]

One method is to draw lines on the lock plate that extend the four faces of the tumbler square so they can be seen outside the profile of the cock. Center the cock over the tumbler with the shoulder lined up on the edge of the plate and transfer those lines back to (up and over) the surface of the cock. They will provide a good starting point for filing the corners in the round hole you have drilled.

Of course it also helps to drill the largest possible round hole through the cock so you can slide it a bit front and rear and actually look through the cock to confirm that your layout lines are in the right place.

[Dphariss]

There are several ways.
I generally just eyeball it.
Coat the rear 1/2 of the plate with magic marker.
Put the tumbler through the plate in the "down" position, make sure this is *correct*. You may have to assemble all the internal parts to determine this.
Using a straight edge on a tumbler flat draw a line that the cock will not cover when it is put in place.
Remove the tumbler.
Center the cock over the tumbler hole and put it in the down position. The cock should already be bored to the smallest dimension of the tumbler, across the flats.
Transpose your line to the cock. Move this line till it just touches the hole in the cock. Use this to file a square hole in the tumbler. For best results the tumbler should be tapered slightly with a short bevel at the outside edge to keep the tumbler from shearing metal when installed. A slight taper on hole is good too.
The tumbler needs to tight in the hole. If not the cock may very well come off in use and/or get loose and flop around a situation that just gets worse and worse and will require repair.
It I can press it on and off with a 1 1/2 ton arbor press I call it good. The first installation with lubed parts (STP works) will size the hole so once its started and the dimensions are close I just press it on if too much pressure is not needed. Its a feel thing. It its too tight press it out and continue fitting. If forced on you can break something going on or coming off.
A vise can put a LOT of pressure on things so if using a vise for the pressing BE CAREFUL.

Dan

[D. Taylor Sapergia]

I use the system that Gary has described.  I ground a square file so that only one flat has teeth...the other three are polished.  Then having outlined the square hole around the drilled one, it's a simple matter to take out the corners.  Keep a little draft in the hole...larger on the inside than the outside, so that the cock fits tightly on the tumbler square.  And go slowly.  Good luck Doug...see you in a couple of weeks.

[Stophel]

Very carefully.  I will hold the cock on the tumbler about where I want it, and scribe (best I can) the square where I want it.  I will eyeball it from every angle I can to see if it is where it should be (and hopefully it is) before squaring it out.  I make my holes/tumblers slightly tapered, so I can adjust the angle SLIGHTLY as I go down...but not much.

[doug]

     I think I like Roy's suggestion best.  In the past I have been drawing lines and transfering them to the cock with mixed success.  If the plate is small and the base of the cock is large, particularly when working with a blank, I find it easy to be off a bit.  A thin layer of solder and a light tap with a hammer should work well; will try that on the next one.  Hopefully I will have my current project shootable but probably not finished for Heffley.  I started with the remains of a gun I suspect was made in the late 1700s.  Lots wrong with my work but am learning slowly (very slowly)





cheers Doug

[jerrywh]

Drill a hole in the hammer the minor size of the square desired. I make a small sleeve to fit that hole. the sleeve will just fit a screw the same size as the threaded hole in the tumbler. Clean the hammer. Spray the lock face and tumbler shaft with WD40. let sit a few minutes. Position the tumbler in the fired position. Put a small amount of body filler on the back of the hammer around the hole. Screw the hammer in the fired position on the tumbler thru the sleeve that is in the hammer hole. Let set for 15 minutes or until the body filler is hardened. Take out the screw and slip off the hammer. Push out the sleeve in the hammer. Position the hammer in a drill press face down on a level block with a hole under the hammer hole. Using the drill press push the correct size broach thru the hammer hole in the position indicated by the imprint in the body filler. If you do this correctly it is the most precise method of replacing a blank hammer. It is not the fastest. It is faster than doing it two or three times. The tumbler should have a slight taper on the shaft.
 If the tumbler or the hammer hole is not tapered the hammer will eventually loosen.  Do it once do it right. No charge.  If you don't have a broach , either buy one of make one. I have hammer broaches that I made over 40 years ago. If the broach is slightly undersized you can file the hole to fit. Just be careful to keep a slight taper in the hole.
 Try not to get dody filler in the tumbler hole.