Lock tuning help needed

[pcrum]

Hi All,
Last night I decided to tune my lock on a Pedersoli Bess. It was a little rough on cocking. I polished the mainspring and tumbler where they rub together, using emery paper on a needle file. When I reassembled, it worked great, but only for about the first ten times, then it started getting stiff, and squealing like a rusty hinge. Eventually it gets to where it ampost won't cock at all. I disassembled, and found that the mainspring was wearing grooves into the tumbler. I disassembled several times, and re-polished it, only to have the same result each time.
What Did I do wrong? Do I need to harden the tumbler after doing this? If so how do I do that? If not, what can I do to fix it? I have a re-enactment the weekend after next and need to get this operational.

Thanks In Advance,

 

[sherpadoug]

My Bess is giving me fits, so maybe I am not one who should be giving advice. But I would smooth the tumbler and spring tip and try a different grease. It sounds like the parts are galling, not sliding. Maybe a grease with graphite, teflon, or mollylube would help.

 

[rich pierce]

Did you leave any emery dust on the lock parts? That could explain part of the problem. If not, your lock needs help. If the mainspring is galling the tumbler, then the tumbler is not properly hardened and it's a matter of time before you lose your notches and it becomes unsafe. The mainspring should always be softer than the tumbler.
I'd suggest that somebody who works on locks a fair bit work on this one, unless you can get it warranteed.

I work on locks, there are plenty of other guys too, maybe you can find someone locally.

 

[pcrum]

Did you leave any emery dust on the lock parts? That could explain part of the problem. If not, your lock needs help. If the mainspring is galling the tumbler, then the tumbler is not properly hardened and it's a matter of time before you lose your notches and it becomes unsafe. The mainspring should always be softer than the tumbler.
I'd suggest that somebody who works on locks a fair bit work on this one, unless you can get it warranteed.

I work on locks, there are plenty of other guys too, maybe you can find someone locally.

The Gun is 10 years old, and has had hundreds of live and probably 1000 blanks (including clatches and flashes : through it. I think that I may have unintentionally polished through the hardened layer. Warranty is obviously out of the question.
Is there some way I can safely re-harden the part myself, by heating it to the correct temp and quenching it in oil, or is there more to it? The Cam area (for lack of a better term) where the spring rides is definately soft. The hardening must have been pretty thin.

Thanks again,

 

[TANSTAAFL]

If you have determined it is soft, I have used Kasenit for decades to harden small parts, easy to use, just follow simple directions.

 

[Zonie]

Sounds like you'll have to struggle thru the weekend with it.
As others have said, the tumbler is too soft.

If you decide to use Kasenit, don't follow the instructions.
Kasenit is made for carburizing low carbon steel, and at the moment, you don't know if your tumbler is low carbon steel or improperly hardened high carbon steel or tool steel.

The part of the instructions to avoid the first time is the directions which say to quench the red hot part in water .

I would suggest quenching it in oil . Then check the hardness with a file. If you can't file it, then temper it per the instructions below and your done.

If you can file it , put on another coat of Kasenit and then water quench it.

After quenching, polish it up and temper it by baking it in your wifes oven at 410-440 degrees F for a half an hour. It will be a very light yellow color.

 

[pcrum]

Thanks Zonie (and others of course)
I still have this weekend to get things ready, hopefully I can find someone nearby that has Kasenit.

It's definately soft as it files easily right now.

Cheers,

 

[pcrum]

An update for those interested.
I went up to tipp city to pick up some Kasenit and spoke witht he guys there. They told me that all I needed to do was heat up the tumbler cherry red and quench it in oil. I did that today and the lock seems to be working great now. I picked up some Kasenit anyway, but didn't use it.

Thanks again to all that gave advise!
:hatsoff:

 

[rich pierce]

Good luck with that fix; I hope it holds. If it does, no worries. But I have my doubts!

If the tumbler was hard only on the surface before, and your polishing removed the surface hardness, this indicates it was case-hardened mild steel. Heating and quenshing will not harden mild steel.

If, for reasons not clear to me now, the tumbler was made of carbon steel and not properly hardened, then you might have a very brittle tumbler on your hands right now, and it could crack. It needs tempering, or "drawing" if it is hardened tool steel. I'd check to see if a new file cuts it or not. If not, you may want to take it out, put it in the oven at 475 for an hour, turn the oven off, and let the oven cool. Then take the tumbler out and re-install.

 

[pcrum]

Good luck with that fix; I hope it holds. If it does, no worries. But I have my doubts!

If the tumbler was hard only on the surface before, and your polishing removed the surface hardness, this indicates it was case-hardened mild steel. Heating and quenshing will not harden mild steel.

If, for reasons not clear to me now, the tumbler was made of carbon steel and not properly hardened, then you might have a very brittle tumbler on your hands right now, and it could crack. It needs tempering, or "drawing" if it is hardened tool steel. I'd check to see if a new file cuts it or not. If not, you may want to take it out, put it in the oven at 475 for an hour, turn the oven off, and let the oven cool. Then take the tumbler out and re-install.

When I got done quenching it in oil, I tried cutting it with a file- It would scratch the surface just barely with some effort. definately much harder than before. So should I go ahead and temper it then?
I worked the lock about 50 times yesterday, and it's definately not galling or scratching the tumbler anymore.

I have a very limited knowledge of metalurgy so I appreciate all the input and info. In fact I don't even know what I did by heating and quenching it- It just followed the instructions given me and it seemed to work.
Thanks Again,

 

[rich pierce]

I'd temper it to be safe. Then you should be good to go for a long time.

 

[pcrum]

I'll do that tonight then-won't do any harm right?
Just for my own curiosity, what happens when you heat temper the piece? I actually don't know what happens when I quenched it either. Quenching it made it hard, so does tempering it make it softer? if so, what is the reason for doing this? wouldn't it negate the quenching process?
Sorry for my ignorance!
::
Thanks,

 

[rich pierce]

Simple answer: heating for an hour in this temperature range will make it a tad softer and much tougher, less likely to break. It should still be harder than the spring when you are done.

I'm no metallurgist so can just parrot some of what "took" out of what I have been told. Heating high-carbon steel to a critical temperature (red-orange) causes the molecules to change their relationship to one another and they even lose magnetic activity at that heat. They are all moving around, not aligned. When quenched in oil or water the molecules in the steel quickly crystallize into a form that gives great hardness. It is also very brittle in this state. The faster it cools (water may be faster than some oils) the harder and more brittle it will be. Example of very hard steel that is very brittle: if you take a file (pick a worthless one and wear eye protection), stick it in a vise with 6" sticking up, and pound it one good whack with a ballpeen hammer, it will break off very easily just above the vise. Just like glass. A cold chisel will not do that. It's been tempered. It's still hard, but not brittle.

Once hardened then "drawn" or "tempered" to different temperatures, the steel becomes somewhat softer and much tougher. The heat can oxidize the surface and give colors you can see that progress with higher heat. Yellow or straw color requires the least heat and is used for very hard edged tools that cut steel. Next is dark straw, kind of brownish. Then purplish, then mighty purple, then blue, then gray. You've seent hat beautiful blue color on old clocksprings, I am sure. Much also depends on the carbon content of the steel and other elements in the alloy.

 

[pcrum]

First of all, Thanks for the explanation. That makes sense.

But it seems my troubles are far from over! :curse:

I tempered it in the oven at 475F for an hour, then turned off the oven and let the part cool in there overnight. This morning while breakfast was cooking, I put the tumbler back in, and it's too soft again- the spring is back to it's old tricks. So I guess my next step is to go ahead and use the kasenit? Should I use it on the entire tumbler or just the bearing surface where the spring rides? I think I recall that I need to maintain the cherry red temperature after applying the Kasnit for a couple of minutes before quenching is that correct?

I really appreciate all the advise,

 

[Zonie]

Yes, you need it on the surface where the mainspring contacts it, and you also need it on the full cock sear notch.
The Half Cock notch is optional because the sear really isn't under a lot of pressure when it is entering or exiting this slot.

You will find that applying the Kasenit is far from a precision operation. Just make sure the surfaces are well coated.

After coating, you are correct in maintaining a cherry red condition for a couple of minutes before quenching it.
Actually, as long as there is Kasenit on the surface, the longer you hold it at red heat, the further into the base metal the carbon will penetrate. The deeper it penetrates, the thicker the hardened case will be.

By the way, I'm not sure whether to suggest quenching in oil or water. The oil quench should have hardened the steel if it was a tool steel, and the tempering at 475 degrees should not have softened the surface enough to permit the spring to gouge into it.
Your comment that the tumbler could not be cut with a file, leads me to think it is a tool steel, in which case, the oil quench would be the way to go.

As I mentioned either on this post, or another one, you can oil quench it after using the Kasenit. It won't hurt it, but it may not harden it very much if it is low carbon steel.

If the oil quench doesn't seem to harden it much at all, then reheating it and water quenching should do the job. A little prayer here might help because, as was mentioned, water can cause tool steel to shatter.

WEAR GLASSES when you do this, espically with the water quench. When the red hot part hits the water, the melted Kasenit will instantly harden and shatter with a loud POP! throwing little pieces of it, and some water on you, so be prepared.

After quenching, do the polishing thing and the 475 degree bake again. (straw yellow to yellow brown should be the tempered color).

By the way, this 475 degree temper should develop a hardness similar to drills and taps so the spring which would have been tempered around 570 degrees should be softer. If anything wears, it should be the spring.
If the spring was incorrectly tempered at a lower temperature, I would expect it to break, but not knowing what the spring is made from, anything is possible.

 

[Gary]

Zonie - you know your stuff. :hatsoff:

 

[pcrum]

Thanks again Zonie,
I'm going to try to take care of it this afternoon.
Best Regards,

 

[pcrum]

Hi Again,
I went at it again last night- I used Kasenit this time. Oil quenched it the first time, it was still scratchable, so I did it again with a water quench- you weren't kidding about that stuff popping and splattering water everywhere! This time is was super hard, I could barely scratch it at all with a file and it took considerable effort. I then polished it up a little, and popped it in the oven at 475 for an hour, then let it cool. It seems to be working great- I compared it to another pedersoli bess I have and other rifles- this lock is the smoothest action I've ever seen on any bess.
I really appreciate all the help and advise!

One last question, and I'll leave you alone for now... ::
When I got done tempering the part in the oven, Zonie, you had mentioned a straw color? mine had more of a color case hardened look- lots of wavy colors thoughout. Is that still ok?
Cheers,

 

[Zonie]

It should be no problem. ::

There is nothing holy about the colors. They are primarly indicators of the tempering temperature and there may have been some contaminents on the surface that caused it to look mottled.

Glad it came out ok.