Broken screw in Becky lock

[Rawhide Rick]

Long story short.  As is usually. The case, a friend brought me a project.  The head of the cock screw broke off leaving the shaft just below the surface of the square part of the tumbler.  I know the tumbler is harder that $#*!, and I managed to get most of the screw out.  But, mill bit wobbled just a little on the last size I used, and got in the threads,  seems 5x40 is what it was.  I tried carefully to tap it to 6x40 and broke the bottoming tap.  Now looking at EDM to get the tap out. 

My question is, can this hole be brazed up, and drilled/tapped back to 5x40 without a problem?  Or will brazing heat the piece up too much.  There isn’t really any stress on the threads, it only has to keep the cock from popping off the side of the lock.   Fortunately, I was upfront with him about my chance of success, and I don’t want to mess with trying to re-harden it correctly.

[rich pierce]

Brazing temp is very high and will make the tumbler lose its hardness. It should be impossibly dangerous to try to drill and tap or re-tap a hardened tumbler.

[Rawhide Rick]

That sounds like replacement is the only option?  And I haven’t been able to find any parts for that lock in the usual places.  Wonder if someone here might have parts?

[smallpatch]

I think Track has Becky locks and parts.

[sbowman]

yes replacement is best option if you don't want to mess with heat treatment. I assume you called Chambers directly?

If you go the edm method to get the tap out the heat generated is gonna mess with hardness of the tumbler anyway I'm thinking; at least where you need to rethread. 

Steve

[sbowman]

correction to above post.  I was thinking Chambers small Queen Ann and missed the "Becky" part.  Call Log Cabin Shop.  If anyone has it they will.

Steve

[Rawhide Rick]

I looked online but didn’t see parts available, even at Track.  I can call log cabin shop and see if they have something.  Thanks for the input guys.

[smylee grouch]

Call Cabin Creek, I think they could get it out and redrill/tap and harden again.

[flatsguide]

You might consider a carbide drill for a 50% tap hole the a carbide tap. If you try this you will need a very rigid setup. You mentioned, “mill bit wobbled”, I take from this you have a mill; make sure the X & Y axis is locked down as is the part fixture securely, you don’t want any movement. I would get a screw machine drill sometimes called a “stub” drill, it has less flex. I’d also consider a two flute carbide end mill of the correct diameter for the screw threads.
Good luck!
Richard
PS I just saw Smylee’s post and I think that may be a better, cheaper way to go...instead of “cheaper” let’s say less expensive than my suggestion.

[adkmountainken]

finding a replacement is not going to be an option on fear as i have had 2 members now tell me they have tried in vain for years to find replacement parts for a Becky lock.

[Goo]

It sounds like you have machine equipment. Have you thought of maybe just making a new tumbler?  sometimes its easier to just start over.  I`ve made new tumblers twice for old locks just keep in mind everything lines up on the imaginary radial lines off the axle.   Hardening is not so difficult with the cherry red nitride,  it doesn`t need to spark like a frizzen then draw it back a little after hardening.   

[P.W.Berkuta]

If it was mine I would anneal and normalize the tumbler then remove broken tap via EDM or other methods? Then tap the hole to clean it up if possible if not then weld or braze it up and re-drill & tap it.

[Jim Kibler]

I would mill out the broken tap.  You can cut a broken HSS tap out with a carbide milling cutter.  I'd then tap it to 6-40 like you previously tried.  Hopefully it's not too hard to accomplish this.  Just using the original thread would be better if it's not too buggered up.  If it's necessary to up-up size the thread, and the tumbler is too hard to tap, You can anneal it and then re-harden and temper it.

To anneal it just make a little pile of charcoal briquets, light them and place the tumbler on them.  This will heat your part up and hold it at a decent enough temperature for enough time to soften it pretty well.

To re-harden, you really ought to know the material and process that was originally used.  Absent of this, heat up to around 1525 F with a torch and oil quench then temper at around 500-550 F.

Jim

[Liza]

R.E. Davis has some Becky lock parts. The Becky lock is an Allen Manufacturing lock that Davis assembled years ago. Allen is not providing enough parts to make this lock again but we do have parts to keep the locks already out there running. Please feel free to give us a call and we can get you what you need. Monday - Saturday 8:30 until 6:00. 330-948-1082

[adkmountainken]

BIG THANK YOU to The Log Cabin Shop they had a Becky tumbler and promptly put it in the mail for me! another BIG thank you to RawHide Rick for the work he has done! hope to call him in a longbeard in another month as a thank you!

[Rawhide Rick]

Update, I did get the broken tap out.  Stuck a punch in the hole and rapped it with a small hammer.  It broke in two.
I’m not comfortable trying to re harden the tumbler without a kiln, which I don’t have.  I don’t mind screwing up my own stuff while experimenting, but I don’t like screwing up someone else’s stuff.

Fortunately, Ken was able to get a replacement, so maybe this one will be experimented with at a later date.  I appreciate all the input.