I was sharpening some knives last night on the belt sander and noticed that my kitchen knives dont spark at all. The CS machete sparked like crazy, but the steak knives I was sharpening didnt. I assume they are stainless, but you cant tell after they've been in the sink for a day or so. I wonder if they are even hardened? Or is it just a property of the stainless, or the fact that I was using a sander instead of a wheel?
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Sparks During Grinding
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Cougar Allen
Buccaneer (ret.)
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The more the sparks fork the more carbon is in the steel. Sounds like you didn't get any spark at all from your kitchen knives, though. I don't know, maybe if you press harder....
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When grinding knives, the plain carbon steels spark a lot, and an experienced eye can judge from the spark pattern the type of steel it is! Stainless steels can spark, but from my experiences of grinding 440-C and ATS-34 (and other steels just in sharpening), they don't spark that much. They don't spark at all in sharpening as per my methods.
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Yes - the same can be said for D2, S30V and other high-alloy steels.
The spark test really only works for simple steels. The hotter the spark, the higher the carbon content. I can light up a good sized room with a bar of 1095 doing heavy grinding....
The spark test really only works for simple steels. The hotter the spark, the higher the carbon content. I can light up a good sized room with a bar of 1095 doing heavy grinding....
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Iron sparks are particles of burning (oxidizing) metal. Stainless steel is formulated not to oxidize or to only oxidize slowly--hence it doesn't show much sparking on a grindinq wheel and even less on a sanding belt. A simple carbon steel and a lot of pressure would kick up some serious sparks.
"Stainless steel is formulated not to oxidize or to only oxidize slowly--hence it doesn't show much sparking on a grindinq wheel and even less on a sanding belt."
Duh, I shoulda guessed that before writing this post. As for sharpening on a belt sander, I've done all my knives on it at one time or another. I usually use it to reprofile, then switch to waterstone and sharpmaker for sharpening at the new angle. A 300 grit belt and a leather belt work well for the kitchen knives though. They get abused and can take a long time to sharpen by hand. And I did ruin a couple of knives (read 6) sharpening them on the sander. One was a S&W hunter, one was a broken BM Ares, and another was a (gasp) BM 806. Well, the 806 was already stripped of coating and hand sanded to 400 grit, so the 320 scratches weren't that noticable. The only damage to heat treatment was to the S&W. I've gotten the hang of it since, and love the edge the leather belt produces.
Duh, I shoulda guessed that before writing this post. As for sharpening on a belt sander, I've done all my knives on it at one time or another. I usually use it to reprofile, then switch to waterstone and sharpmaker for sharpening at the new angle. A 300 grit belt and a leather belt work well for the kitchen knives though. They get abused and can take a long time to sharpen by hand. And I did ruin a couple of knives (read 6) sharpening them on the sander. One was a S&W hunter, one was a broken BM Ares, and another was a (gasp) BM 806. Well, the 806 was already stripped of coating and hand sanded to 400 grit, so the 320 scratches weren't that noticable. The only damage to heat treatment was to the S&W. I've gotten the hang of it since, and love the edge the leather belt produces.
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FWIW, I sharpen every knife I make on a 1x42 belt sander. Have yet to burn an edge - just keep a can of water nearby and dunk every few passes. Work at higher grits and move slowly. Piece of cake.
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When I have a lot of kitchen knives to sharpen at one time (say 50 of them) I do most of the job on my belt sander. This happens every two to four months when I bring knives down to prepare food at the local soup kitchen. It is amazing how fast three dozen amateur chefs can dull knives. When I have really dull knives of any type I do most of the reprofiling or edge restoration with a belt sander. If it is a valuable knife I start with a fine grit, if I don't care about the looks much I start with a coarser grit. For a machete I might start with 60 grit and work up to 400 grit.