How do you mount a bushing ?

[Rolf]

I've got a pair of lock kits from Blackley for a pair of Le paige pistols that have been collecting dust for a couple of years, do to problems with the internal parts.

The parts are so small that it is impossible for me to drill the screw holes in the cast sear and bridle. I'm going to have to make new parts.
I plan to drill the holes first and shape the blanks around the holes afterwords.

But the thing that bugs me the most, is the tumbler hole in the cast lockplate. It is to big for the tumbler and not completely round.
I want to ream it out and install a bushing, How do you keep the bushing from falling out of the plate?

Best regards
Rolf

[Old Ford2]

Hi Rolf,
Why can't you heat shrink the bushing into the lock plate?
Fred

[Keb]

Drill the hole same as O.D. of the bushing. It can have some clearance but not much (.002ish). Once the tumbler is in snd the hammer is on the tumbler, the bushing can't escape.

[EC121]

Keb is right.  I've watched the millwrights in the shop put bearings in journals.  They use a close fit and heat the journal.   Then it would usually slide right in but had to be pressed out.  A close fit on a small piece and some permanent thread locker or JB Weld would work for your piece.  It isn't going to be turning 3600rpm like the bearings we had. 

[Bob Roller]

Putting a bushing in a lock plate isn't hard but care must be taken and careful measurement must be made so the job is a success.I had some Manton castings that were so flimsy that it would have been impossible to make a durable lock from them.Can you post pictures of these parts on the Forum? How big is the tumbler hole as it came from the foundry?
DON'T just drill a hole,drill it undersize and then REAM it and use a good cutting oil on the reamer so it will be the correct size. As an illustration,if the hole in the lock plate is out of round,get a reamer that will barely make it round.Make a FINISHED bushing .001 over the finished hole and with the tumbler hole also reamed and thickness of the lock plate thickness of the lock plate taken in to consideration when finishing the bushing.
Warm the lock plate just hot enough so it can't be touched and then tap the bushing in and let it cool off.
Another thing is to be careful not to make the bushing so big that it will interfere with the bridle screws.
In 1968,I made up a pair of "Manton"left and right flintlocks and the plates were so thin that it was nearly impossible to get a good thread for the bridle screws and as I recall,I went two sizes under the recommended tap drill size for a 5-40 thread.
Good luck with this project.

Bob Roller

[smart dog]

Hi Rolf,
I had to install bushings in every lockplate casting bought from the Rifle Shoppe and Blackley's that had the tumbler holes cast in.  I now order plates with the tumbler holes filled.  Bob's method is also my method with one significant change.  I case-harden my lockplates and want the bushing to stay in place during treatment.  Consequently, I very slightly counter sink both sides of the tumbler hole, insert the solid (undrilled) bushing into the hot plate, let cool, and then lightly peen both sides into the counter sinks.  I file off the excess and then drill the tumbler hole.  I mark that hole in the bushing before installing it, which is easier to insure that it is centered.  I suppose you could install the bushing without the counter sink and then harden it and the plate together.  If it fell out during heating just reinstall it again as before but I like to know that it is permanently locked in place.  Let me add that the bushings worked very, very  well.   Good luck my friend.

dave  

[Jim Kibler]

Other options are to weld shut or braze in an oversize plug and then re-drill. 

[chubby]

I also do as Bob says i drill ream make my bushing 1 to 2 thousands bigger and throw it in the freezer for a while the brass will shrink, then press in. when it warms up it will tighten and not come out! Chubby

[Mark Elliott]

You order bushings from the industrial supply company of your choice by ID and OD.    The actual OD is .002" over size for what is called a "press fit".   For example,  if you order a .5" OD /.375"ID bronze bushing,  you would drill a .5" hole in the plate.    This will be about .002" smaller than the bushing.   Then you just press or hammer the bushing into the hole in the plate.   You can't get a .125" long bushing, so you order a longer one and cut it off once in the plate.   I order .75" long bushings so that I can bush at least three plates with it.  I cut the bushing off on the inside of the plate using a jewelers saw and then file the bushing flush with the plate on both sides with a #2 swiss warding file.   Commonly available bushings and bearings are sized to make this easy, and it is as long as you have good machine shop practice for drilling and reaming holes. 

[smart dog]

Hi Rolf,
To clarify and avoid some confusion, I use 1045 carbon steel round bar stock not bronze or brass for my bushings. 

Good luck,

dave

[Rolf]

Hi Rolf,
To clarify and avoid some confusion, I use 1045 carbon steel round bar stock not bronze or brass for my bushings. 

Good luck,

dave

Thanks Dave, I was about to ask about that. What are the pros and cons with steel verus bronze bushing?

Bob, I'll try to post pictures of the parts later today.


Best regards
Rolf

[smart dog]

Hi Rolf,
I can harden the steel to resist wear.  Perhaps that is not necessary but seems logical to me since the tumbler is hardened steel as well.  Some bronze alloys can be pretty tough so they might make good bushings but I don't think brass would be a good choice.

dave

[Habu]

Yep--brass bushings (done by brazing the hole up, then drilling and reaming to the correct size) do tend to get a little loose around 5k-10k cycles, depending on the lock.  Haven't shot a lock with a bronze bushing enough yet to know what to expect. 

[Bob Roller]

A few years ago I was making bell housing and other bushings for automatic transmissions that hadn't been made for years like Packard Ultramatic,GM Jetaway,Borg Warner and others and I used bearing grade bronze #660 and had no reported trouble.Also made king pin bushings and steering box bushings from it as well.
If you have a small piece of that material it will make a decent lock bushing for the tumbler.In automotive applications it stood up to heat quite well and that will never be a problem with the gun locks.

Bob Roller