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Rifles, Reloading, Optics, Equipment
Gunsmithing
Pedersoli Sharps chamber pressures?
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<blockquote data-quote="shortgrass" data-source="post: 430026" data-attributes="member: 24284"><p>I've used the Casenite before on small parts that need some hardness, the only color it seems to leave is gray. True "color case hardening" is having the part you want to harden 'packed' in a crucible with carbon rich material such as bone or wood charcoal and heating in a heat treat oven to between 1335 deg. & about 1400 deg. for a predetermined length of time. Charcoal made of leather was used at one time in the past but, since chromium is now used in the tanning process, it no longer is used or desirable, needs to be 'brain tanned' leather. (Cyinide 'salts' were and are still used today, but that's not a process I deal with. I 'm not sure if 'salts ' transfer any 'color', either.) When you get the crucible and its contents up to 'heat' carbon transfers to the surface of the part you are heat treating (the crucible is a sealed container and the part(s) and charcoal inside have to be 'packed' in a certain way, very tightly, so as to eliminate as much air as possible to prevent oxidation and combustion). I've never heard a resonable explination of where the colors come from, could be the impurities from the charcoal, who knows, but I do know, different charcoals produce different colors and different hardness. I have found very little technical information in print, some good stories and basic info, though. Most of what was known by the men of the past that did the work was kept in their heads or personal note book and was lost when they pasted. The story goes, When Colt decided to re-intoduce the SAA they had to run an extensive R&D program for the case hardening, there was no or very little technical info from the past. Another story goes, When Colonel Hatcher took over operations at the Springfield Armory (the Springfield '03 was in production then) he discovered that the temps were being judged by the operator visually in the case hardening process. After installing the then new pyrometers as much as a 200deg. could be possible just because of a cloudy day. Heat treat got better after the pyrometers were installed. Alot of this is art to this day. It takes alot of time and failures to get even a slight handle on the process. I learned the basics at a NRA Summer week long class, but spent the next two years, off and on, refining to the point I felt comfortable doing a Rolling Block or a box lock shotgun action. Part of the high cost of doing color case hardening today is in making the blocks/braces for parts of thin section that will warp out of control if not blocked of braced. Going from above 1330 deg. to air temp fresh water tends to do that. The blocks/braces don't last very long as they warp too. Those nice "Case Colors" of yesteryear were and are a by-product of the hardening process. Some of the high quality guns of the day had the color polished off and then they were rust blued. Those 'colors' can be had with a modern chemical process, but I know nothing about it. I'd be glad to e-mail some of the articals I have a accumulated over the years if you would like, just PM me an e-mail address where I can send attachments. You're right, it's a 'dead' topic on this forum, not 'magnum' enough , I guess.</p></blockquote><p></p>
[QUOTE="shortgrass, post: 430026, member: 24284"] I've used the Casenite before on small parts that need some hardness, the only color it seems to leave is gray. True "color case hardening" is having the part you want to harden 'packed' in a crucible with carbon rich material such as bone or wood charcoal and heating in a heat treat oven to between 1335 deg. & about 1400 deg. for a predetermined length of time. Charcoal made of leather was used at one time in the past but, since chromium is now used in the tanning process, it no longer is used or desirable, needs to be 'brain tanned' leather. (Cyinide 'salts' were and are still used today, but that's not a process I deal with. I 'm not sure if 'salts ' transfer any 'color', either.) When you get the crucible and its contents up to 'heat' carbon transfers to the surface of the part you are heat treating (the crucible is a sealed container and the part(s) and charcoal inside have to be 'packed' in a certain way, very tightly, so as to eliminate as much air as possible to prevent oxidation and combustion). I've never heard a resonable explination of where the colors come from, could be the impurities from the charcoal, who knows, but I do know, different charcoals produce different colors and different hardness. I have found very little technical information in print, some good stories and basic info, though. Most of what was known by the men of the past that did the work was kept in their heads or personal note book and was lost when they pasted. The story goes, When Colt decided to re-intoduce the SAA they had to run an extensive R&D program for the case hardening, there was no or very little technical info from the past. Another story goes, When Colonel Hatcher took over operations at the Springfield Armory (the Springfield '03 was in production then) he discovered that the temps were being judged by the operator visually in the case hardening process. After installing the then new pyrometers as much as a 200deg. could be possible just because of a cloudy day. Heat treat got better after the pyrometers were installed. Alot of this is art to this day. It takes alot of time and failures to get even a slight handle on the process. I learned the basics at a NRA Summer week long class, but spent the next two years, off and on, refining to the point I felt comfortable doing a Rolling Block or a box lock shotgun action. Part of the high cost of doing color case hardening today is in making the blocks/braces for parts of thin section that will warp out of control if not blocked of braced. Going from above 1330 deg. to air temp fresh water tends to do that. The blocks/braces don't last very long as they warp too. Those nice "Case Colors" of yesteryear were and are a by-product of the hardening process. Some of the high quality guns of the day had the color polished off and then they were rust blued. Those 'colors' can be had with a modern chemical process, but I know nothing about it. I'd be glad to e-mail some of the articals I have a accumulated over the years if you would like, just PM me an e-mail address where I can send attachments. You're right, it's a 'dead' topic on this forum, not 'magnum' enough , I guess. [/QUOTE]
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