produres with thinner stock using stock removal

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DarrenW

Joined
Dec 8, 2013
Messages
13
Hey Gang,

A friend at work asked me to make him a chisel ground japanese style "chef" knife. I've looked at various brands and sizes and they seem to be approx 3/32" thick and what appears, best guess calculated from pictures and specs, to have a grind angle of about 10 degrees. I haven't decided on using 3/32 or 1/8 steel yet but based on your comments I will see.

Considering I will be using stock removal as my method and heat treating using a forge (1080+ 1/8" or O-1 3/32" steel) what would be the better route to take:

A) should I heat treat at full thickness and grind edge from there? This would help prevent warping while using such thin stock but with such a narrow grind angle I run the risk of ruining the heat treat.
B) grind blade as usual then heat treat? Super thin edge, how much should I leave in thickness considering potentially burning the steel etc?

Any thoughts or guidance are always welcome.

Thanks
Darren
 
O1 makes a great kitchen knife. Use 3/32" and heat treat it full thickness. You can grind your 45* bevel on the edge first but not much more than that or the blade will warp.

As soon as it comes out of the oil put it between two plates of aluminum. Really, anything dead flat will work. This will make sure the blade stays flat. Then while you grind make sure you use sharp belts and dunk the blade in water every pass. Also make sure you don't wear gloves while you grind. That way you know how hot the blade is getting.
 
Just grind hard. It will give you peace of mind and its really not any harder on belts. I hard ground 3 knives out of 62 rc 3V today and it wasnt that bad. Theres nothing worse than losing a blade in HT.
 
jawilder said:
O1 makes a great kitchen knife. Use 3/32" and heat treat it full thickness. You can grind your 45* bevel on the edge first but not much more than that or the blade will warp.

As soon as it comes out of the oil put it between two plates of aluminum. Really, anything dead flat will work. This will make sure the blade stays flat. Then while you grind make sure you use sharp belts and dunk the blade in water every pass. Also make sure you don't wear gloves while you grind. That way you know how hot the blade is getting.
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What Jason said will keep you out of trouble. Only thing I might add is that if the blade happens to warp slightly, then putting it between aluminum plates won't help much if the temp out of the quench has gone below 400-ish.

Whether you grind hard or easy, the key is fresh belts and do not to let the blade exceed the targeted tempering temps. Can we say "Cool Often".

Robert
 
I am glad I found this. I am planning on using some 3/64" or 1/16" thick O-1 for a round knife.

I have used 3/32" O-1 and hardened it before grinding and had no problems with the warp.

But I worry about the 1/16" or 3/64" thick. Is there anything else that can be done to help prevent the warp? I kind of agree with Robert Dark, the plates wont help much if it is cooler than the 400F.
 
HT then grind. It will take longer and you have to be careful not to over heat the work. Have a dip bucket net to you or have a misting/cooling system next to the platen.

TheWeatherman said:
I am glad I found this. I am planning on using some 3/64" or 1/16" thick O-1 for a round knife.

I have used 3/32" O-1 and hardened it before grinding and had no problems with the warp.

But I worry about the 1/16" or 3/64" thick. Is there anything else that can be done to help prevent the warp? I kind of agree with Robert Dark, the plates wont help much if it is cooler than the 400F.
Click to expand...

Post HT, for a full flat, edge to spine, if you are grinding the bevel one side at a time it will develop a curve towards the side where material is removed. The higher the grit, and more scratches the more the curve will develop. This curvature will alleviate and even out as you remove material on the other side. Just remember to adapt your technique to compensate for the curvature of the blade as it passes across the flat platen.
 
+1 for what folks have already suggested. I do a fair number of thin blades and switched to post HT grinding on almost everything 5/32 and thinner, particularly if it's not a short blade.
I switch sides nearly every pass, work bare handed and dip and wipe every time. New, not just newish, belts are your best friend on thin stock. Also, on stuff that thin, start at 80 or even 120 grit with belts like the Blaze or similar ceramics. I tend to think about it as a percentage system until the finish refinement stage. I want each pass to remove X% of the metal. If I start out super thin I need to take off much less metal per pass and have much less room for error with a coarse belt. You could trash a thin blade in moments with a 36 grit ceramic.

I haven't done one lately, but I've got a pair of 3/32" CPM154 kitchen knives to grind soon. There's something really nice about a thin full height grind ending in a fine edge. Hefty bowies and utilitarian EDC's are great, but I've always felt that a really good slicing knife or even sword was the ultimate expression of the personal blade.
 
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