casehardening Hawkens

[Jim Curlee]

I'm still up in the air, about casehardening of Hawkens.
Was this a common practice on Hawkens rifles?
If not, what was the favorite method of metal finishing?
Jim

[D. Taylor Sapergia]

When Don Stith was a member here, he spoke of metal finish on original Hawken guns.  He said that all hardware was pack hardened, but was simply grey or mottled grey...includes butt plate, trigger and guard assembly, tang and breech plug, toe plate, nose piece, slides and escutcheon plates, entry pipe.  The barrels were blued...either charcoal blued, or rust blued is my guess.  On some originals one can still see the case colours but they are subtle.

[WB Selb]

65pan,

I was fortunate enough to own an original S. HAWKEN  ST. LOUIS rifle in shooting condition, the finish was pretty well worn but the case colors were readily visible on the inside of the lock plate, the barrel had traces of blue left on the underside of the barrel where it was protected by the forearm. I cannot help but wonder just how dull the original case colors really were; when we realize that the "newest" Hawken guns are at least 150 years old, that is a lot of time for the colors to have faded out a bit.

Brant

[Jim Curlee]

Brant, DT;
How fine of a surface are you looking for, before you do the casehardening?Does the casehardening finish, build-up like a browned finish?
Can casehardening be done by the average putz, or does a guy have to be a metal wizard to come up with a nice finish?
Thanks again
Jim 

[WB Selb]

65pan,

It does not take a genius to get a nice cc finish, it takes time. A 320 grit sanded finish is adequate but the sanding marks need to be unidirectional. CC's do not build up or hide as browning does, if anything, it will amplify any boo-boos. The biggest problem facing a person wanting to CC a gun or parts is the need for an oven or furnace that can maintain 1400 degrees for a couple of hr's. and the very real danger of warping your parts when they are quenched; if that happens, they are toast, as they have already been fitted to their mating parts and they are going to be darn near "diamond" hard; the only choice is to anneal and start over. In summery, it is not real difficult, it is time consuming, there is a risk of failure, the results, when properly achieved, are worth it.

Brant

[westerner]

Case hardened and case hardened with colors produces a hard skin on the parts leaving the core soft.  If the parts warp they can be bent back to shape.  If the part is extremely thin it could break.

                Joe.

[Dphariss]

Case hardened and case hardened with colors produces a hard skin on the parts leaving the core soft.  If the parts warp they can be bent back to shape.  If the part is extremely thin it could break.

                Joe.

If the part has a significant surface hardness and it warps and is then bent to back to the proper shape it there is an excellent chance of cracking the hard surface. Its hard, its not very flexible.

Dan

[westerner]

Case hardened and case hardened with colors produces a hard skin on the parts leaving the core soft.  If the parts warp they can be bent back to shape.  If the part is extremely thin it could break.

                Joe.

If the part has a significant surface hardness and it warps and is then bent to back to the proper shape it there is an excellent chance of cracking the hard surface. Its hard, its not very flexible.

Dan

The hard skin being part of, and not lying on the surface of the core, goes where the core goes.  A thin piece could crack or break completely through.


                  Joe.

[keweenaw]

When one is pack hardening lock plates, hammers, breeches, etc. you're not trying to to turn them into gears, you're trying to put .005" of hardness on the surface.  If you do this correctly, quench so the parts fall into the slack tank end first and never on their sides, you're not going to find they ever warp to the point of being "toast".  Original parts were made of wrought iron or at most very mild steel and the cores simply didn't harden appreciably and any warp or twist is easily removed.   Teh old tiem gun makers, including the government arsenals were case hardening their stuff and they weren't tossing it out because it was getting warped.   The only parts where the casing is thick enough relative to the core thickness to potentially cause problems is with thin trigger guards or butt plates but then these parts are usually springy enough to put back into their inlets without removing any warp.  Massive pieces, like standing breeches and patent breeches are massive enough not to warp.

The same goes with modern cast parts if they're cast from 8620.  Any warp is very gentle and can be removed without undue difficulty.  Now the Rifle Shoppe parts are all cast from 4140.  When you quench that in water it not only gets a hard surface on it but hardens through.  Trying to straighten them will result in a break.  TRS part can, however, be color cased by quenching from below critical temperature.  This doesn't give the glass hard surface but does give a tough piece and can give excellent colors if that's what one wants.  On all large investment cast parts it's best to normalize or stress relieve the material before you assemble the lock, etc. as any internal stresses are removed.

Enough of this BS that is you caseharden stuff you're likely to ruin it.  You have to know what the material is cast from  and know what you're doing.  If you don't know either of those you shouldn't be doing the work.  If you do know, you'll not have any problem.

Tom

[Dphariss]

Case hardened and case hardened with colors produces a hard skin on the parts leaving the core soft.  If the parts warp they can be bent back to shape.  If the part is extremely thin it could break.

                Joe.

If the part has a significant surface hardness and it warps and is then bent to back to the proper shape it there is an excellent chance of cracking the hard surface. Its hard, its not very flexible.

Dan

The hard skin being part of, and not lying on the surface of the core, goes where the core goes.  A thin piece could crack or break completely through.


                  Joe.

Apparently you have never had a casehardened part develop surface cracks when bent.

Dan

[Dphariss]

When one is pack hardening lock plates, hammers, breeches, etc. you're not trying to to turn them into gears, you're trying to put .005" of hardness on the surface.  If you do this correctly, quench so the parts fall into the slack tank end first and never on their sides, you're not going to find they ever warp to the point of being "toast".  Original parts were made of wrought iron or at most very mild steel and the cores simply didn't harden appreciably and any warp or twist is easily removed.   Teh old tiem gun makers, including the government arsenals were case hardening their stuff and they weren't tossing it out because it was getting warped.   The only parts where the casing is thick enough relative to the core thickness to potentially cause problems is with thin trigger guards or butt plates but then these parts are usually springy enough to put back into their inlets without removing any warp.  Massive pieces, like standing breeches and patent breeches are massive enough not to warp.

The same goes with modern cast parts if they're cast from 8620.  Any warp is very gentle and can be removed without undue difficulty.  Now the Rifle Shoppe parts are all cast from 4140.  When you quench that in water it not only gets a hard surface on it but hardens through.  Trying to straighten them will result in a break.  TRS part can, however, be color cased by quenching from below critical temperature.  This doesn't give the glass hard surface but does give a tough piece and can give excellent colors if that's what one wants.  On all large investment cast parts it's best to normalize or stress relieve the material before you assemble the lock, etc. as any internal stresses are removed.

Enough of this BS that is you caseharden stuff you're likely to ruin it.  You have to know what the material is cast from  and know what you're doing.  If you don't know either of those you shouldn't be doing the work.  If you do know, you'll not have any problem.

Tom

I have seen original parts damaged/ruined by attempts to case harden them by people who casehardened modern parts by the thousands. Specifically old Remington and Sharps receivers. The Remington, a Hepburn in this case, warped so that the breechblock would no longer fit and required a lot of hand work to get the block to fit.
The original Sharps action "finned" at all the forging lines when quenched so it had a sharp edge standing about .050-.100" high at every "forging line" and there were many of them.
A friend casehardened a Remington Rolling Block hammer and it broke through the pin hole. He then bead blasted one half then glued it back onto the part with the bright colors. He then used to produce questioning looks on the faces of visitors to his shop. The hammer and block of the Rolling Block action are high carbon and it broke when water quenched.
An engraver/gunmaker who posted here at one time strongly recommended blocking engraved lockplates.
So if the part is valuable, being an expensive part or perhaps one with a lot of engraving its best to block it and have someone with experience do the casehardening.
I have also seen original parts with cracks from the original casehardening process. A friend tells me this is common with some original single shot designs.

Dan

[westerner]

No Dan I have not seen surface cracking.  I dont have the vast experience you've had either.   

As far as the amount of color we get now compared to the the old time makers. The old makers were not trying to replicate what old timers did like we do today.  My guess is that we now try for the most brilliant colors in the quest to do it like the old makers.  That makes me suspect todays colors are much brighter.  Most of the breech plugs in my old percussion rifles show case colors on the protected areas. They tend to be darker, softer, with a little more green color than todays case colors.  What they actually looked like when brand new, we'll never know that for sure.

                Joe.

[keweenaw]

As I said, don't do it if you don't know how.  If this were all typical Doug Turnbull would had been out of business a decade or more ago.  Most of the problems Dan mentions are simply too much heat for too long and inappropriate orientation of parts in the pack.  It is absolutely well understood that parts grow in a carburizing process.  Many precision parts, gauges, etc. are carburized first and then ground to finished dimension.  So if you take a Hepburn receiver and block and carburize the snot of of them, the parts aren't going to fit afterwards.  I had a Parker in the shop that someone had done that to that you could no longer get the barrels to close in the receiver.  The problem wasn't that it was warped but rather that the hardener had put such a depth of case on it that the dimensions had changed and there wasn't that much clearance to start with. 

Tom

[Jim Curlee]

So, you do get a built up suface?

Tom;
What grit paper are you taking your metal to, for casehardening?

Thanks
Jim

[keweenaw]

It's pretty generally agreed that there is no point in polishing past a worn 400 grit wet or dry paper.  The grit isn't as important as the quality of the polish with all the marks being in the same direction.  Of course there can't be coarser grit scratches under the finial polish.  The surface isn't built up per se.  When the steel is at critical temp the surface opens up molecularly and the carbon in the pack as CO migrates into the steel or iron.  Obviously if it's in the pack long enough you are adding material to the near surface of the metal, hence the dimensional change.  But even relatively short periods of time at critical temperature have an influence on surface finish and the tiny polishing scratches of the 400 grit paper tend to disappear in the final hardened surface.

Tom

[Swampwalker]

Knowing that some dimension changes occur, are the threads of the breech plug protected during the hardening process (say, by sheet metal) so that it will fit back in the barrel?

[keweenaw]

That's not a problem as there is enough thread clearance that one draw it up to alignment and it's kinda hard to protect things against gaining carbon in a pack as it's all gaseous diffusion that's moving the carbon into the steel.   It only becomes a problem when one is dealing with clearance between things like a tumbler shaft and the hole in the lock plate.  On a carefully hand built lock that clearance might be less than .001" and things can get tight after casehardening.  Most commercially assembled locks will have more clearance than that.

Tom

[greybeard]

I recall an article in M B years ago where John Bivins  was color case hardening a patent type breech plug for a restoration tutorial and he gave the plug threads a copper wash claiming that case hardening will not penetrate the copper wash on the threads. It  worked for him and can see no reason that it won't work for you.  It would be prudent to try it on a test piece and see how it turns  out as you really don't want deep case on the threads??
Cheers    Bob

[keweenaw]

The point of all this case hardening of lock plates and breeches is NOT to put on a deep case.  All we want to do is to put on a hardened surface and/or do a colored surface.  One can quench from below critical temperature after a relatively short pack and get good colors without adding appreciable amounts of carbon to the surface or hardening the piece.  When our goal is to  harden these pieces what we want to do is to put on a wear surface to slick things up and prevent galling of parts.  0.003" to 0.005" is plenty to do this, will result in almost unmeasurable dimensional change and will not turn ductile pieces of metal into fragmentable objects.  These thin layers of case are also not likely to develop the surface cracks in the hardening process that Dan pointed out can happen with very deep cases, nor will they render pieces so brittle that they can't be straightened or sprung a bit if necessary.

Case hardening pieces for impact resistance or to add major amounts of carbon to the surface of something like a frizzen or a tumbler or sear made from mild steel is another matter all together.  In those case the pieces are either small enough or massive enough that they won't warp in the quench and we want enough depth of hardness on things like tumbler notches that we can change angles, etc. by stoning without cutting through the case.  The procedure isn't any different for achieving this, one just runs above the critical temperature of the steel for longer periods of time.  One extremely high end gun makers who makes his own locks makes his frizzens this way -  He takes a block of mild steel and forms the face of the finished frizzen on it. The entire block is then packed and cooked for 6-8 hours which will put 0.040-0.060" depth of case on it.  The block is cooled in the pack such that when it comes out it will still be annealed soft.  He then works out his frizzen.  The surface carbon is cut away everywhere in doing this except on the frizzen face.  When he's done with his fitting and engraving the piece is heated up to critical temp, in a pack to prevent scale or in an atmospheric controlled oven and quenched.  This hardens the face of the frizzen while leaving the rest fairly ductile.


Tom

[Jim Kibler]

I hear what your saying Tom, but I don't think we can forget just how low of a strength and ductile wrought iron is.  The carburizing  to a depth greater than the thin surface layer you mentioned, adds considerable strength to wrought iron parts.  The approach of a very thin case on modern steel for difficult part configurations may work fine, but when considering 18th century materials, I think it may become a little fuzzier.  I know the Williamsburg gunshop practice it to carburize much deeper than the depths you suggested.  I am not certain of their current process, but I believe JHAT mentions carburizing hold times in the range fo 3 hours at temp. 

[Dphariss]

Casehardening breeches raises the spectre of brittle threads. This is my primary concern. So deep cases may be a bad idea here, especially when 32 tpi liners may be used or 28 tpi nipple threads.
One way to help combat this is to anneal the part at 350 degrees or slightly more, just not high enough to destroy to color.

Dan

[Jim Kibler]

I'm going to be carburizing a breech plug for a fowling piece soon and intend to use stop off paint to restrict carbon absorbtion in the thread region. 

[Roger B]

I recently read through a large number of threads on case coloring/hardening in the archives.  I was struck by a number of fellows who used Kasenit & quenched in aerated water infused with potassium nitrate.  This obviously isn't pack hardening, but might do for those of us without a forge or furnace.  Any comments from the congregation?
Roger B.

[Swampwalker]

It seems like it would be hard to get an even deposition of carbon on anything very large - say a lockplate - using Kasenit.
Jim, I'm not familiar with the 'stop off paint' you mention.  Where do you get it from?

[Jim Kibler]

Stop off paints are a brush or spray on surface coating that restricts carbon absorption.  The best method is copper plating.  We used them now and then at a previous job I had.  If you do a search for them, you should find some.  I think "Duffy" may be one manufacturer.