Tumbler Notches - Simple Repair

[rhmc24]

 
  
Today at 11:21 AM  
Working on locks we often see worn tumbler notches & fixes such as filing them deeper, installing a sear that reaches farther, etc.  This is a simple fix I have used.  Usually the tumbler is hard and has to be annealed, then make a cut similar to the sketch below & solder in a piece of hard steel.  I have used pieces of spring, hacksaw blade, etc.  I use the 3% silver solder that has a working temp similar to regular soft solder but is much stronger.  It might be best to harden the tumbler again before soldering in the new metal. The half-cock notch may need a thicker insert.  

[smart dog]

Great info Richard,
Thanks.  Why not post these gems in the gunbuildling or tutorial sections?  They are relevant to either forum.

Thanks again,

dave

[rhmc24]

1 was unable to find how to contact the form administrator about posting as a tutorial.   Seemingly rigid discipline of the forum made me decide against 'gun building' and since no gun-fixing or restoration section, here seems the alternative.  From the furor about spring making & spring welding, General Discussion is probably appropriate.

[smart dog]

Hi Richard,
Well I thank you for posting and appreciate the information.  Your book on rifle making was my initial guide to gunmaking.  I still have it after 35 years.

dave

[Majorjoel]

Could this repair be successfully used to make a half cock notch on a tumbler that never had a half cock notch?

[Acer Saccharum]

Rhmc, I'll move this over to the tutorial section in a few days.

This is a great way to save an old tumbler. Thanks, Tom

[rhmc24]

Majorjoel question "Could this repair be successfully used to make a half cock notch on a tumbler that never had a half cock notch?"

I see no problem using it to make such a notch, provided the shape or curvature of the tumbler allows it.  I think I would file a notch in the tumbler & get it working OK, then install a piece if necessary.  The trial notch may be OK without any installation. In any case, working on a half-cock notch needs careful planning to avoid a problem of interference with the sear when fired from full cock.

When you anneal the tumbler to file it, you will have softened the full cock notch also and will need the tumbler hardened again.

[KLMoors]

Very nice tip.

I wish I had the time to shoot enough to wear out parts!!

[Majorjoel]

Thank you Richard for answering my question. In the past I have usually just sought out a replacement tumbler, but with your excellent pictorial method I will certainly give this a try!  Certain lock problems have always been very intimidating to me.  I just need to get my hands dirty with oil and grease and metal filings more often! Step up to the plate....so to speak.

[Bob Roller]

 That was an interesting repair shown in the drawing.Most locks on American
 percussion rifles,unless they are high quality types have only full cock and IF
 a first position "half cock" is added,a fly or detent may be needed if the rifle is
equipped with set triggers. I think the last tumbler repair I made on a lock was in 1980
and it was on a Whitworth long range with a Brazier lock.The tumbler broke off
flush with the lock plate and I made a new tumbler for it. I made a new 4 screw bridle
for another Whitworth a couple of years ago and am convinced these elegant English
locks have some iron parts that are brittle as glass because of the hardening techniques
of the time.
 
 Bob Roller
 

[rhmc24]

Making a tumbler is a real challenge that I have done only a few times when making a lock from scratch.  OIOH I have replaced a lot of tumbler shafts, usually in flint reconversions.  When fitting a repro hammer it's a task to fit it to an old tumbler square.  After a few times I decided it was easier & more accurate to make the square hole in the hammer, fit a square into it & then fit that shaft into the tumbler.

Similar experience with glass-hard parts of English locks, mostly 1800 to 1840s, some of it seemingly unnecessary.  Probably their obsession with perfection.  I still don't see the need for flint hammers being glass hard, brittle & subject to breakage.  I've heard a theory that they got harder over time, which I doubt from what little I know of steel.  Yet it's strange a pistol went thru its use-life and had a failure 150 years later.  My clients wanted repairs that looked original which I did by welding, replacing a little engraving & a finish.

[tallbear]

I still don't see the need for flint hammers being glass hard, brittle & subject to breakage.

It's most likely that they are case hardened and while hard on the outside are soft on the inside.

Mitch

[Bob Roller]

 Some of those parts may not be steel but cast iron like an old stove.
 In spite of the sometimes stunning workmanship in these old English
locks,I think the materials they had available was nowhere near as good as
what is used today. I use 1144 Stressproof for tumblers,0-1 flat ground for
sears and the fly,1075 for main and sear springs.The screws are 12L14 except
the little one the mainspring link swivels on and it's usually 0-1 drill rod.
The 1144 machines like 12L14 but will harden in oil and so far,I have had
but one to come back broken.It was from a German who said it had been modified
by one of their people who used a hardening process that made it brittle and the
arm snapped off.

Bob Roller