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How to do Color Case Hardening

no-clue

Iron
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#2

Tom,
First off let me say WOW! Nice work and holding true to the Stevens level of appearance, kudos my man. IRT the color case hardening I found packing the part in a mixture of hand ground dry cow or horse bone, (my preference being the latter) and Hickory wood charcoal dust gives the richest most colorful spectrum Also the pattern can be varied by how you quench the cherry red part, every manufacturer used a different method Stevens would randomly use a jerking motion while quenching their parts. Others would agitate the quenching medium with bubblers or simply by hand. Also the jury’s out on whether you should have a skim coat of oil floating on top of the bath, I’ve tried both with no apparent differences noted. One note of caution there tends to be warp age to some of the smaller thinner items ie the hammer and thinner areas of the receiver at times so expect some refitting of parts and trueing up the receiver again

Looking forward to seeing this puppy doing range time. Keep up the quality work!
 

Tom Griffin

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#3

Tom,
First off let me say WOW! Nice work and holding true to the Stevens level of appearance, kudos my man. IRT the color case hardening I found packing the part in a mixture of hand ground dry cow or horse bone, (my preference being the latter) and Hickory wood charcoal dust gives the richest most colorful spectrum Also the pattern can be varied by how you quench the cherry red part, every manufacturer used a different method Stevens would randomly use a jerking motion while quenching their parts. Others would agitate the quenching medium with bubblers or simply by hand. Also the jury’s out on whether you should have a skim coat of oil floating on top of the bath, I’ve tried both with no apparent differences noted. One note of caution there tends to be warp age to some of the smaller thinner items ie the hammer and thinner areas of the receiver at times so expect some refitting of parts and trueing up the receiver again

Looking forward to seeing this puppy doing range time. Keep up the quality work!
Thanks Marlin,

Obviously I'm not quite ready to do any color case hardening yet, but hope to be soon. I've been looking around for info on CCH and this seemed like as good a write up as any. My Favorite isn't a direct copy of the Stevens Favorite. It's sort of my interpretation of it. I've made several internal engineering changes to make it easier to build without the need for castings, so some parts won't be interchangeable with the real thing. Call it artistic license if you like.

I've read about some of the techniques you describe and look forward to experimenting with them before I tackle hardening my receiver.

Thanks for the tips.

BTW, I just caught the pun in my original post and it truly was unintentional. :eek:

Tom
 

Tom Griffin

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#4
My Starrett 711 DTI looks like that. Would it have been colour case hardened? I was worried when I got it - I though it had been abused or left out in the elements.
Lol. Yes, Starrett color case hardens some of their tools though I doubt they would see the humor in your description of their finish. :rolleyes:

Tom
 

44-henry

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#5
Hello,
I am new to this site, but found this thread while looking things over. I actually wrote the tutorial for the Home Model Engine Machinist forum that was linked at the start of this topic. One thing I would caution about the Marlin thread (I was also on that forum many times in the past) is that the person who did this work was quenching the receivers at a very low temperatures, i.e., 1250 F. I do research in casehardening at the University of North Dakota and have done fairly extensive testing on this process over the last five years and the low temperature issue frankly disturbs me.

While there is going to be some difference in hardness, in my opinion, you should never quench below the critical temperature, say 1370 F (varies), if you want to actually harden the surface. Strangely enough the colors are oftentimes better at these temperature ranges under critical, but hardening is superficial if at all. This is not good if the original design specified a hardened surface. Of course, the reason that some like to do this is not only the pretty colors, but also the fact that the shock at these lower temperature ranges is considerably less than it would be if quenching took place above the critical (higher) temperature range. Consequently there is probably less chance of metal movement and thus reduced risk of damaging the receiver, or having to spend considerable amounts of time hard fitting components afterwards. Frankly I block everything I care about and expect to have to do some post fitting when moving parts are involved. I would not shy away from this task at the expense of a properly hardened part.

I rarely, if ever, caseharden parts much under 1425 degrees F and prefer to soak them in the 1450 range knowing full well that the pack will lose temperature between the time it leaves the furnace and can be delivered in the quench tank. Carbon absorbs faster at higher temperatures, but quenching above 1500 tends to produce very dark colors and above 1600 they pretty much dissappear altogether. This said, a lot of industrial carburization takes place in the 1600 plus range. I have soaked parts at higher temperatures and than dropped to low temperatures for the quench with some success however.

I have never had any problem obtaining very vibrant colors with my process and rarely do much more than wrap the parts in soft iron wire before placing them in the crucible. My standard mix is 50/50 wood/bone and either tap, or distilled water. We have used oil skims and various admixtures in the quench and also run air lines, but frankly, plain old cold tap water freshly poured does as good as anything. Filling a container shortly before the quench allows proper agitation which gets the oxygen content up to a point that you need and the wire creates disturbance enough to give you the spectacular patterns you are after. The wire also helps hold the charcoal mixture in contact with the workpiece for a longer period which also helps with the colors.

If anyone has any questions about the process I can be reached at: ajohnson@business.und.edu.

Regards,

Alex Johnson
 

Tom Griffin

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#6
Thanks for the comments Alex, it's good to get information directly from the source.

It sounds like the guy on the Marlin thread was more interested in color than hardness if he's quenching that low. I would rather quench for hardness and take whatever color I can get. My Steven's project isn't quite ready for hardening yet, but it's getting close. I need to get over to Ebonex and pick up some bone charcoal, it doesn't seem to be available anywhere else unless you want to pay a fortune for it a Brownell's.

Tom
 

Gunsmith

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#7
Receiving a good deal of information regarding the Colour Case Hardening process from the posts is much appreciated ...still there are a few questions I need to ask...keep in mind I have zero (nothing) practical experience with cch ..these questions focus more on the chemical processes...maybe a metallurgist will be able to provide some insight?... ..but:

1)In which sector are the colours (tan,cobalt blue, hue, straw ect) obtained or created...in the pack -compound or in the quench tank ...when are these colours created?

1 a)How are these colours created...which chemical process take place?

2)What ingredient can be added to create a specific colour? more cobalt blue or hue colour? Where (into which ) do you need to add the specific ingredient to attain the sought-after colour? quench tank or pack composition( bone -charcoal/charcoal)?

3)Which added ingredient will give you what colour?

Regards

Gert
 

squidly87

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#8
The American Custom Gunmakers Guild has a video for sale on their website concerning Color Case Hardening and Nitre Blueing:

http://www.acgg.org/index.php/resou...997-seminar-1-color-case-hardening-nitre.html

The cost is $35. I have no idea what it covers or if it is even any good, it's just something I ran across recently.

Incidentally, if you haven't been to their site it is worth checking out. They have a number of resources available on a variety of subjects and the free sample (PDF) copy of their magazine "Gunmaker" has lots of great tips.

http://www.acgg.org/

Randy
 

Harry Eales

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#9
The very best source of information on Colour Case Hardening can be found here :-http://www.marlin-collectors.com/forum/viewtopic.php?f=21&t=3732&sid=fff443322de44ac6480bdfe492c43a25
The thread runs to 30 pages and it takes a while to real all the pages and digest the information. Unlike many so called 'Experts' the writer actually shows his results and the methods of obtaining them. The two part article by Oscar Gaddy is interesting but very much out of date. There is far too much hocus pocus written about CC Hardening. Some of it makes Shakespeares Witches in Macbeth seem to be modern scientists. Just as an aside 'Wing of Bat and Eye of Newt seem to make the finish too green' lol.

Harry
 

tfranktoo

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#10
Thanks for the comments Alex, it's good to get information directly from the source.

It sounds like the guy on the Marlin thread was more interested in color than hardness if he's quenching that low. I would rather quench for hardness and take whatever color I can get. My Steven's project isn't quite ready for hardening yet, but it's getting close. I need to get over to Ebonex and pick up some bone charcoal, it doesn't seem to be available anywhere else unless you want to pay a fortune for it a Brownell's.

Tom
So I read you entire thread and you are the reason that I found this website AND the reason I joined also!!! I wanted to see how your Favorite turned out as I am in the process of converting an 1894 Favorite that was originally chambered for 32 Long to 17 Mach2. I have relined the barrel and relocated the FP in the breech block so that it hits the rim of the 17 Mach2 correctly, but I am wanting to beef up the breech block pivot screw and that was the specific thing I was wanting to look at on your build. Very impressive machine work on that receiver by the way!!!
I'm primarily over at RimFireCentral and either on the Mossberg or Hunting forums. But I did some work on a Stevens Crackshot that had seen better days and in researching info for it I discovered the Favorites and I decided that I should have one!!! A member of the Stevens/Savage forum was able to tell me that Stevens case hardened their receivers according to some original literature he has, which would certainly explain why the threads in the receiver were able to reform the threads on a new breechblock pivot screw that I made out of a grade 5 bolt. So since the receiver is case hardened I have to anneal it so I can work on it properly, which means I need a heat treat oven, so I have to figure out how to fabricate one of those!!! I've been researching that for a while so I think I will be good on that, but now I find this info on CCH and I really like the looks of it. I will not be able to remove all of the dings and dents from the receiver but now added to the list is to CCH my Favorites receiver even though it is a very well used receiver with how shall I say... lots of character marks!!!
Well the whole point of this response was to see where you were at on YOUR Favorite. Is it CCH yet??? If so any pictures???
God Bless, Frank.
 

Tom Griffin

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#11
Thanks for the compliments Frank and I'm glad you are enjoying the build. My thread on the Steven's Favorite is being hosted here on Hobby Machinist and over on MetalworkingFun. It's idle at the moment, because I've had to take time out to work on a paying project for a while, but I'll be getting back to the Favorite soon. The latest push has been getting set up to drill and rifle the barrel.

If you are looking to build a heat treat oven, I've recently discovered a digital control that is inexpensive and would work very well. All you would need is the control, a high temp type K thermocouple and a solid state relay to control the resistance element in the furnace. You can check out the control on this thread. Also, this guy goes into great detail about how to build a furnace built around a heating element for a kiln. You may want to purchase his book on the subject.

Tom
 

tfranktoo

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I've been researching what I need to make a smallish heat treat furnace and ordered most of the controll items off of one guy on ebay. The PID controller, the SSR and its heat sink and a high temp thermocouple. Still need to order the soft fire bricks, the heating element and the high temp hook-up wire for the element. Since I read the info in the link on the casting furnace that you supplied in the above post I may decide to use his recipe for the castable refractory used in that article rather than buy "Fiber Fax" insulating blanket. I still need to make a mock up of a prototype before I know how big this heat treat furnace will be. It will need to be big enough to hold a steel pot big enough for a number of small parts plus a receiver, and long enough for a decent sized knife blade.
By the way thanks for the "this guy" link!!!
God Bless, Frank.
 
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44-henry

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#13
The very best source of information on Colour Case Hardening can be found here :-http://www.marlin-collectors.com/forum/viewtopic.php?f=21&t=3732&sid=fff443322de44ac6480bdfe492c43a25
The thread runs to 30 pages and it takes a while to real all the pages and digest the information. Unlike many so called 'Experts' the writer actually shows his results and the methods of obtaining them. The two part article by Oscar Gaddy is interesting but very much out of date. There is far too much hocus pocus written about CC Hardening. Some of it makes Shakespeares Witches in Macbeth seem to be modern scientists. Just as an aside 'Wing of Bat and Eye of Newt seem to make the finish too green' lol.

Harry
I am just curious what would make you figure that the Gaddy articles are out of date? I have looked at images of color case hardened surfaces under electron microscopes and they appear, in most respects, exactly how Gaddy reported them to be. In addition, his study of the process was based on years of personal experimentation. The Marlin thread that you reference is not the only look at the process and there have been many others who have taken the time to detail the work that they do with plenty of detail for those who wish to re-create the results. I certainly hope that you are not grouping the rest of us as the "so called experts". Also, the gentleman who did all the work in the Marlin forum was not casehardening, he was coloring. His quench temperature was far too low to yield any substantial hardening and that is not a really good idea when working with something critical like a receiver. Anybody who has done any heat treatment would see the problems with his process. Just because his results looked pretty does not mean that his work stands as the definitive work on this subject.
 

GunsmithD

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#14
Thanks for posting all of this information. I have been studying CCH and this thread has set me on the best paths. I will continue to research and acquire the pieces needed to do this. I am going to start on small pieces and make practice pieces and hopefully I will eventually be able to CCH. The first actual gun I want to do is the frame to my 1911. I am curious if anyone knows the size/shape of fixtures that I will need to make to prevent warpage. Right now, the only thing I KNOW is the pieces need to made of Stainless steel, as well as the crucible. Any information will help!

By the way, this tread is what got me to join the forum and I am loving what I am seeing everywhere else.

-Chris
 

Harry Eales

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Thanks for posting all of this information. I have been studying CCH and this thread has set me on the best paths. I will continue to research and acquire the pieces needed to do this. I am going to start on small pieces and make practice pieces and hopefully I will eventually be able to CCH. The first actual gun I want to do is the frame to my 1911. I am curious if anyone knows the size/shape of fixtures that I will need to make to prevent warpage. Right now, the only thing I KNOW is the pieces need to made of Stainless steel, as well as the crucible. Any information will help!

By the way, this tread is what got me to join the forum and I am loving what I am seeing everywhere else.

-Chris
Chris, before you start to CC Harden you should find out the type of steel used to make your 1911 frame. Only very low carbon content steels can be CC Hardened. Having worked on a great many .45 Colt semi-automatics I would be very wary of CC Hardening the frame as it is very thin in many places and there is a great chance of warping. Get in touch with the manufacturer of your pistol, (there were many), give the model and Serial No and see if they can tell you what specification steel was used in it's manufacture and how it was heat treated. The carbon content should be no more than 0.1%, if it is more than that, forget about it, you would be better off leaving it blued. Stainless steel is not necessary for a crucible, mild steel works just as well and is a lot cheaper. Don't forget that any steel that has been previously heat treated has to be annealed prior to CC Hardening. Harry.
 

44-henry

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Chris, before you start to CC Harden you should find out the type of steel used to make your 1911 frame. Only very low carbon content steels can be CC Hardened. Having worked on a great many .45 Colt semi-automatics I would be very wary of CC Hardening the frame as it is very thin in many places and there is a great chance of warping. Get in touch with the manufacturer of your pistol, (there were many), give the model and Serial No and see if they can tell you what specification steel was used in it's manufacture and how it was heat treated. The carbon content should be no more than 0.1%, if it is more than that, forget about it, you would be better off leaving it blued. Stainless steel is not necessary for a crucible, mild steel works just as well and is a lot cheaper. Don't forget that any steel that has been previously heat treated has to be annealed prior to CC Hardening. Harry.

I wouldn't be too quick to caseharden a 1911 frame. I do a lot of gunsmithing projects and I am well versed in the color casehardening process, but that is a job for a specialist like Turnbull Restorations. As Harry mentioned stainless steel is not required for crucibles, I probably go through a dozen or more a year of mild steel ones, but they are cheap and they work fine. Stainless is nice too if you have some, but not necessary.

On a side note, high carbon steels can be colored using the color case hardening process, it serves no real useful purpose other than putting the colors on the part, but it can be done. Following the operation they need to be tempered and as long as you don't go much beyond 450 degrees F you won't mess up the colors, in fact, I generally draw most of the parts that come out of my tank at 450 following the quench because I feel that it enhances the colors.

Regards,

Alex Johnson
 

GunsmithD

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44-Henry and Harry Eales,

Thank you for the information. I got my hands on a 6" by 8" Stainless tube, I will make the crucible out of. Just needing a base to weld onto it.
The plan is, trail and error the crap out of this process before doing it to my frame. My frame is a Norinco, so it is a fairly hardened steel in first place. I plan on making some supports through the magazine well, the grip safety/mainspring housing area, and the barrel support. All that to decrease the warping. Will probably make a support for the slide/frame meeting point, maybe not, though. That is an easy fix. It will be a while before I can do this, but I will update as I can.
 

awander

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#18
I'm having trouble understanding the "wrapping with iron wire" part. Is it done is a loose wrap, or tightly, and is it supposed to completely cover the parts to be CCH?
 

gocy

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#19
Just finished reading Tubal Cain's Hardening, Tempering and Heat Treatment. Very interesting, and has a separate chapter for Casehardening
 

Whyemier

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#20
First off I'm as much in the dark about color case hardening as the most ignorant person on this site, which come to think of it could be me. I did see a YouTube video ( see link below) of Uberti's method of color case hardening. They boil the item (in this case the frame) in a salt compound, don't know what salts they are using, then quench it in water. This seems to be all they do to achieve the finish we all like so much.

Still don't understand it but perhaps someone here could enlighten me/us more on this method and if its practical for the hobby machinist.

http://www.youtube.com/watch?v=qYOJa8ZNxmE
 

Metalshaper

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#21
the salts "can be" cyanide based and would definitely not be a home based thing. :panic:

NOW pack hardening, that is the home shop version of Case hardening !!

Respect Always
Metalshaper/Jonathan
 

John Hasler

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#22
You can't harden steel by boiling it in a water solution. That's just a surface treatment similar to Parkerizing and its ilk.
 

Whyemier

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#23
All I can go on is what the Uberti video said. Though I now see this would be impractical for home/hobby machinist. I don't think I mentioned boiling in water though. I guess that could be inferred from salt solution but its not the same thing.
 

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#24
From my research and study...
the salt "baths" have nothing to do with boiling.. and the addition of water is a very serious safety issue in this process.
Super heated salts tend to explode when moisture is added < kind of like a drop of sweat in a lead melting pot >
The hardening solution< if you will >is made by heating the cyanide salt crystals themselves ( no water added ) The heated salts melt and
form the 'fluid' used in the hardening process..

Respect Always
Metalshaper/Jonathan
 

John Hasler

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#25
Right, but the stuff in the video is obviously boiling water.

From the ad copy I see on their Web site I suspect that they've come up with a water-based chemical process that attempts to duplicate the appearence of a frame that was case hardened 150 years ago and then acquired a patina. That does not preclude the frames also being case hardened, of course.
 

Whyemier

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#26
From my research and study...
the salt "baths" have nothing to do with boiling.. and the addition of water is a very serious safety issue in this process.
Super heated salts tend to explode when moisture is added < kind of like a drop of sweat in a lead melting pot >
The hardening solution< if you will >is made by heating the cyanide salt crystals themselves ( no water added ) The heated salts melt and
form the 'fluid' used in the hardening process..

Respect Always
Metalshaper/Jonathan
John,

Please refer to the comment above. It is not obvious to me that it is a water solution. It could be I suppose but water is not needed for a boil such as what is shown in the video.

Other than that, I will leave it to the experts.
 

Pinenut57

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#27
IMG_20150210_112228987.jpg IMG_20150210_112207661_HDR.jpg . IMG_20141023_191118094_HDR.jpg I recently finished building my oven for color case hardening and heat treating. I've been very happy with the results so far.
 

Pinenut57

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[GALLERY=][/GALLERY] I built my own oven and had a friend wire the control box. So far I've had pretty good results, getting some beautiful colors and haven't had any major warpage. I've also been very careful to draw back each piece. IMG_20141023_191128293.jpg f87dd0947633203552a37d36de14674f.jpg f87dd0947633203552a37d36de14674f.jpg IMG_20141023_191128293.jpg
 
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