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- Feb 5, 1999
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- 1,068
There was recently a thread about heat treating and foil. Since I do a fair amount of this, I thought I'd take a look at the methods that were used.
First, I use a KM14D Paragon furnace. I buy my tool wrap from Enco as it works as well as any other place I've purchased it. I do not use the high temp, just the regular and have for years without a problem. That lays out some basics.
There were those advocating a small hole in the wrap. That has always produced scale for me, so I didn't try that again.
Normally I use a small tab of wood inside the wrap. When I'm done there is a piece of charcoal in the wrap. I used to use paper, but always worried because I don't know how much is needed to completely remove the O2 from the packet, so I went to a small tab of wood. I double fold the open sides after I put a blade in, and use a pair of pliers with a 2" wide flat jaw to crimp the folds all around. Got them at a garage sale for 50 cents, a really good investment.
For both tests I used 8 blades, mostly 154CM and a little ATS34. The blades were washed clean in tap water and dried prior to wrapping. I don't wrap the blades so that the foil is tight fitting, but neither do I leave much space for air. Both sets of blades were ramped up to 1950 and held for 25 minutes. That is the standard I use.
The first batch of blades I used a piece of paper about 1/2" square in each packet. That's a lot less combustible than I normally use.
The second set of blades was done without any extra combustibles at all.
In examining the difference, there is quite a difference. The batch with paper in the packet were clean, had the various rainbow colors from heat treating, and a slight bit of soot. A very slight bit.
Batch 2, without any extra combustibles, looked uniformly dirty. There are colors visible, but it really looks like a very thin coat of scale on every blade. I haven't ground any of it off. The amount of scale possible isn't much, but none the less, is present.
So in my own mind and for my methods, I've seen the results and will go back to wrapping blades as I always have. A liitle soot is quite preferable to a little scale. I may not use as much wood and will probably go back to maybe a 1" square of paper, but I will always put something combustible inside the foil packet.
Gene
First, I use a KM14D Paragon furnace. I buy my tool wrap from Enco as it works as well as any other place I've purchased it. I do not use the high temp, just the regular and have for years without a problem. That lays out some basics.
There were those advocating a small hole in the wrap. That has always produced scale for me, so I didn't try that again.
Normally I use a small tab of wood inside the wrap. When I'm done there is a piece of charcoal in the wrap. I used to use paper, but always worried because I don't know how much is needed to completely remove the O2 from the packet, so I went to a small tab of wood. I double fold the open sides after I put a blade in, and use a pair of pliers with a 2" wide flat jaw to crimp the folds all around. Got them at a garage sale for 50 cents, a really good investment.
For both tests I used 8 blades, mostly 154CM and a little ATS34. The blades were washed clean in tap water and dried prior to wrapping. I don't wrap the blades so that the foil is tight fitting, but neither do I leave much space for air. Both sets of blades were ramped up to 1950 and held for 25 minutes. That is the standard I use.
The first batch of blades I used a piece of paper about 1/2" square in each packet. That's a lot less combustible than I normally use.
The second set of blades was done without any extra combustibles at all.
In examining the difference, there is quite a difference. The batch with paper in the packet were clean, had the various rainbow colors from heat treating, and a slight bit of soot. A very slight bit.
Batch 2, without any extra combustibles, looked uniformly dirty. There are colors visible, but it really looks like a very thin coat of scale on every blade. I haven't ground any of it off. The amount of scale possible isn't much, but none the less, is present.
So in my own mind and for my methods, I've seen the results and will go back to wrapping blades as I always have. A liitle soot is quite preferable to a little scale. I may not use as much wood and will probably go back to maybe a 1" square of paper, but I will always put something combustible inside the foil packet.
Gene
Makes the foil come off a little easier digging around under the oil, I think! 
. Something I've been doing the last 6-8 months is saving some of the packs (mostly from my large camp blades) and re-using them for stress relieving, normalizing etc., and having excellent results. It has been said not to use foil packs more than once I know, but this has been working very well for me. I believe stress relieving prior to final austenitizing has all but eliminated problems with warping for me. Good thread Gene :thumbup: