Cylinder Base Pin Maintenance

[Tinker2]

Sjohns

“1. Use stock and lathe it for size and shape, then thread it over sized and tap the frame to match.”

I would make the new oversized one, sized to the threads in the gun. Not re-tap the gun.

“2. Use silver solder to fill up the space that has developed between the threads with a compound that will do it the best.”

You would want to use a flowing type of Silver bearing solder. STL 1260 SILVER
BRAZE is what I would use if I went that way. Whatever you use, must be flowing type.
http://www.brownells.com/aspx/NS/st...VER+SOLDER+PASTES+FOR+THE+PRACTICAL+GUNWORKER

“3. I think using a shim and locktite together is feasible but since there is no data around, it isn't known what sort of longevity is brought with this.”

Most of the ones that I did was over 30 years ago. I have one (brass frame) of my
own that I fixed around then, it had/has NO base pin retaining pin. blind or otherwise.
Works fine. Also has a circular shim installed at the same time.

My first concern is that I don’t have to fix something over.
If it is not worth doing right the first time, it not worth doing over.


Tinker2

 

[gmatov]

hink before you decide what metal to shim with, you best find how MUCH metal to shim with.

How many degrees does it turn when you pull the dowel and tighten up the arbor? Learn that and you can calculate the thickness you need. Personally I would use shim stock, rather than aluminum beer can stock.

For one thing, unless you are really loose, it would probably be too thick. An 18 TPI arbor is a little over 55 1/2 thou per thread, .0555555555555.....ad infinitum.

10 degrees off true is a little over 1 1/2 thou. for a shim.

Also, I would pull the arbor and check to see what the thread actually is. Chicoine says 5/16-18, but I find it strange that an Italian gunmaker, in a metric country, would use inch threads, when they are not being true to size, anyway. The Colt is supposed to be .370-20, which I suppose is an 80% engagement for 3/8 thread.

Cheers,

George

 

[sjohns]

Cant

Here's what the cant looks like:
(pardon my skruffy old truck)

 

[gmatov]

Sjohns,

That isn't the most descriptive pic. How do you determine the angularity from that?

Better you put a straight edge through the arbor slot, wedge it tight, use a protractor from both sides of the frame. Calculate your shortfall from that.

What you WANT to do, is to shim till it comes back parallel, tap in the dowel to the same hole. IF your arbor was bottomed in the hole in the barrel assembly, you still will be.

I don't know if I have any 1 thou shim stock in the garage, mebbe 2 thou. Check tomorrow. If I have, I might be able to send a couple square inches, or punch out a couple, 3 spacers.

I'll let you know with the next post.

Cheers,

George

 

[sjohns]

Thanks George,
I really would appreciate that.

Did you click on the jpeg? It gets fairly large in the browser. I thought that most who were interested in seeing, could see how far out it is. I guess I guessed wrong again. There is a little nub on the right.

Without the proper measuring equipment, I could best estimate it at maybe 10 to 15 degrees or less. It isn't quite halfway to 45. (or 315 if you are aware of clock)

I am a little familar with angular measurement. I know that being a surveyor (artillery and civilian) at times in my life doesn't necessarily qualify me as an expert, but I do have pretty good eye.

George, you aren't going to believe this. I was sitting here typing this and remembering that someone said the pitch of the threads were 5/16 18.
So I was playing with it and was testing that so that I could confirm that in this message and tapped the frame. It took half the wiggle out! But not all of it. Maybe a thin shim is the cure for this one.