Pre-HT edge thickness with 1095...thinner after HT?

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blitz134

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Sep 18, 2013
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Haven't been able to find just the right answer to my question...

I have the bevels filed into my first knife and have moved on to pre-HT sanding. Looking pretty good so far, definitely taken a long time. I read on the forums somewhere that I should target .030" - .040" pre-heat treat edge thickness with 1095. I'm going to make a couple more blades so I can send out for HT at the same time, and I don't want to find I made a mistake and repeated it.

Since I am hand filing should I go thinner? It seems other makers take their edges down to .020" or less before HT...but they are also using other steels.

If .030-.040" is good, then what do I do after heat treat? Do I need to take the edges down thinner before final sanding and sharpening? If so, how thin and how do I do that? I imagine after HT that the blade will be nearly file hard so progress would be slow...so that leaves sandpaper, but even now in the annealed state the material removal rate is incredibly slow.
 
If you are sending out your blades for heat treat, and they are 1095, I would say to take them down thinner myself. It just depends on the heat treater, if they are going to use some sort of anti scale/anti decarb protection. There are a few reasons why the edge should be left a little thick on carbon steel before heat treat. One is of course to prevent bacon edge....wavy edge...due to an edge ground too thin. The other is decarb. A steel like 1095 requires a 10 minutes soak at temperature, so this will pull a layer of carbon out of the steel near the surface. Usually this is only .005" deep, but can be deeper depending on time and temp. Anti scale coatings usually negate decarb, so the edge can be taken down thinner. I would go with .020" if it is going to be professionally heat treated. .030 if doing it yourself with no protection. Those numbers will vary slightly maker to maker.

Almost forgot to answer your question about post heat treat. This is application dependent. Is it a slicing knife (as I see all knives as slicing instruments) or is it going to see more abuse than slicing? I like to go to .005" on just about everything I make. If it is a big camp knife or the like, .010" or more might be better, to give some more "meat" behind the edge.
 
I was also thinking about this question. If I am using salt pots to heat treat my knives what is the thinnest I could grind/sand my 1084 blades before going into the salt pots. And would there be any difference between the thickness of 1084 and let's say 1095?
 
I am not too familiar with salt pots. I have never had the pleasure of using them. But it is my understanding that because there is no atmosphere in the salt (duh), there can be no decarb. Knives that come out of the salt look like they did when they went in, no scale/decarb issues. I would think you could take the edge down thinner when using salts.....but not too thin because it still must survive the quench without warping. Some one else who uses salts can offer better advice...but I think that is correct. As far as 1095 vs 1084, and the thickness of the edge, there would be no difference, if you are using salts.

If you were to heat 1084 and 1095 in an oven, I might would leave the 1095 edge around .025-.030. The reason being is the 1095 requires soak time at temperature, which will pull some carbon out. 1084 does not need time to soak at temp, so there is little decarb to worry about, so maybe .020 would be good. Those numbers are general guidelines. Some makers might use slightly different numbers.
 
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