draw color for straitened flint top jaw?

[ffffg]

my pedersoli mortimer's lock top jaw that holds the flint bent upwards thru the years, maybe becouse it was case hardened and that didnt alow it to be hardened properly.. i heated it up red hot several times to finnaly get it in double plyers and still hot enough to bend back strait so the flint wont slide out as it is tightened between the jaws.. i quenched it in water and reheated it to straw color and it turned a little bluer before i requenched it in water. the black color looks fine on the old lock ive been hunting with for years.. it didnt bend when i put in back in the lock and mounted the flint.. it appears to be hard enough but what im worried about is can it be too brittle with this type of draw??? i dont want it to break in the field and loose the part.(pedersoli does not have much of a parts department) thanks dave..

 

[Tim Clark]

Well, that's a tough call in a way -- when you heated it to red, was it red all the way through? And when you reheated for temper, was it straw all the way through at quenching? Slow is good in that department. But, given what you've written, and the use/application, you should be fine. In essence, you've just "re-case-hardened" it, if you will, and you probably did a fine job of it. It's good that you know your "colors!"

 

[ffffg]

very good point , it was in plyers so the back end where the hole is never got red hot.. so ill do it over again getting it all hot and quenching then drawing by heating the back and watching for color on the fornt like a knife, so the back will be softer and the front harder, and the weak area around the hole wont break, thanks for the help..dave.

 

[Tim Clark]

Well, you may not need to go to all that trouble all over again; also, remember that steel can be overworked, so be careful.

Here's an excellent article on tempering TOOL STEEL, not necessarily gun locks, but I hope it is useful in adding to your knowledge base --
[url] http://www.planemaker.com/articles/heat-treat.html[/url]

Again, personally I'd say you're good as-is, tool steel applications are quite different from the hammer or jaws. After all, as I said earlier, in essence that IS what "case-hardening"/"color case-hardened" is all about. The outside ("case") is tempered for wear and strength, inside is still of lower temper for durability and toughness. You may well have done everything just right.

And with that, I'm going to shut up and let: 1. you decide for yourself, and 2. yield to those more knowledgeable than I.

Good on you for doing it yourself! You'll never forget, and it'll keep you seeking more. Ain't it great?

 

[paulvallandigham]

FWIW, I would not temper that jaw the way you did. I would put it in my oven at about 400 degrees for an hour, and than let it cool slowly to room temperature. I would not recommend quenching after the tempering process. At between 350 and 400 degrees it will turn straw color. You certainly don't want a part that is so hard it is brittle, as it could snap in the field.

 

[Tim Clark]

Paul, that would anneal the steel, giving it strength and hardness not much better than that of a nail. That's fine for bringing the steel to a point of making it easier to work and shape and sharpen, but not for making the piece functional. Of course I may be wrong. However, quenching is the process by which we lock the grain structure transition at that particular point as indicated by color, whereas leaving it to continue to cool as you suggest will let it, if you will, "miss its exit" and go too far south. I agree that heating it and letting it cool slowly at the lower temp is good for resting the grain, but that does nothing for strength/temper. If done as you suggest, would it not make the piece more noodle-like than it was before ffffg started? Just asking, not making a statement. Thanks.

 

[J.D.]

I would suggest that everyone learn about heat treating before offering suggestions.

Paul is right on, provided the part is made of hardenable steel.

Considering that the top jaw bent to begin with, suggests to me that the part is mild steel that has never been hardened.

If you do want to harden that part, heat it slowly and evenly to a bright red, checking with a magnet to determine when the critical temp is reached.

Plain steel parts lose magnatism when the critical temp is reached.

I would suggest inserting a piece of coat hangar wire into the hole and securing with a twist of the wire.

Soak at that temp for a few minutes, and quench in light oil heated to about 130 degrees. A quart of oil is probably enough for a one time use with such a small part. Transmission fluid works as well as any light oil. And slosh the part around in the oil until its warm to the touch.

Have the container of oil CLOSE by, so's the part won't cool as it's being transported to the oil.
It's best to have the container of oil rught under the part as its being heated. Gotta be careful to not turn over the container though. Don't ask.

Using a file, check to see if the part is hard by running the file across the top of the jaw. The file should "skate" across the metal. It should not "bite", or make any file marks on the part.

If there are file marks on the part, it is not made of hardenable steel and there is no need to to temper.

If, and only if, the part is hard, clean the scale and grungy oil off the part and place it in the kitchen oven as Paul suggested.

If the part is still soft, clean it up and install it on the gun. It will probably function as well as as it did prior to "heat threating".

J.D.

 

[paulvallandigham]

Tim: WADR, annealing steel requires you to heat it up to its non-magnetic temperature, and then cooling it down slowly. Heating it to 350 degrees or so, and then cooling it down is how you temper the steel. J.D. has the right order of doing things, with the test of the steel piece with a file after its been heated and quenched in oil. I am use to simply striking the piece with another piece of metal, and listening to the pitch. Its quicker, and doesn't damage my good files! Once you know the pitch of a hardened steel piece, you don't have to do that test with the file. When you temper the steel properly, the picth drops down. Again, its simply a quicker way of determining if you have done the right amount of heat treating to the steel.

 

[J.D.]

In essence, you've just "re-case-hardened" it, if you will, and you probably did a fine job of it. It's good that you know your "colors!"

Tim,
I apologise for being a little short this morning. It was one of those mornings and you were the first target of opportunity.

I understand that you were trying, not only to help, but attempting to learn something in the process. And that is a good thing.

Case hardening is a completely different process than hardening steel.

In case hardening, a low carbon steel part is "cooked" in a carbon rich environment for a period of time. The carbon in the container migrates to the surface of the low carbon steel to a depth of about .010-.020 per hour, depending on the particulars of the environment.

The heated part, charcoal and all is dumped into a container of water as a quench. Most case hardened parts are best tempered at 350 degrees for an hour.

Case hardening imparts a hard shell around a soft core, as opposed to through harding of medium or high carbon steels.

ffffg,
Let us know how your part turns out.

J.D.

 

[ffffg]

when i heated it the second time and put it in water it was quite hard to the file but the file would cut it, but still pretty hard.. i filed a small part near the jaw end underside and heated the screw hole end until it turned straw color on the other end, and flicked it into water instantly.. the filed section was a very light purple and didnt file as hard as before., but held its shape well when i set in back in the lock, put in a flint and sinched her down. it looks like it will be fine, so ill test it tomorrow and see if it can take the punishment..i decided with this metal work i had done i could build a new one close enought to do the job would not be that bad with probably a small siler top jaw from jim chambers..,hoping i could get one without the hole drilled.. but anyway i was in a great mood all day becouse i know i had fixed something that had been nagging me for years.. if it dont hold or breaks ill see if a small siler fits, or can be altered to fit.. dave..

 

[J.D.]

Way to go, Dave. There is a definate sense of accomplishment when a new skill is learned. That is why I try to encourage people to make these repairs themselves. Most of these repairs can be performed with few tools, some basic knowledge, and some encouragement.

That top jaw will probably last as long as the rest of the gun.
J.D.