In what order do you test and grind your blades?

J S Machine

J S Machine

Well-Known Member
I've often wondered what other people do as fas as the order in which their blades are made.

My blades are made in this order:

1. Rough out
2. surface grind or flat grind to obtain a thickness pretty close to what the final will be. Usually +.010-.030
3. hollow grind or flat grind the bevel
4. heat treat
5. check hardness near tang area or area where the scales/handle material will cover the check dimples
6. Draw / stree relieve
7. finish grinding hollow grind or flat grind
8. Surface grind thickness
9. Sharpen blade by hand after everything is assembled (if it is a fixed blade). If it is a folder with a pivot pin I will sharpen before assembly.

What is the order that you do things? I was just thinking about this because someone suggested testing my blade down near the edge in another thread I have at the moment about damascus. I don't know how it is possible to test the thinly ground area created down near where the edge will be. How do you guys test?
 
If your heat treat and temper works well after sharpening it should curl a carpenters nail into a small burr without damage to the blade edge. Some people have the luxcury of a RC tester .
 
Doesn't the metal have to be square to the RC tester? Wouldn't that preclude testing near the edge?
 
Wayne Coe said:
Doesn't the metal have to be square to the RC tester? Wouldn't that preclude testing near the edge?
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Are you saying that the test needs to be done on the edge of the blade blank before the bevel is ground? If so, how do you guys grind your blades without annealing them? I can imagine that these purpose made grinders move a ton of metal and cause alot of heat.
 
cool them off with water as you go, the key to grinding heat treated blades, is when you think you can squeeze one more pass in before you dip the blade - DON'T! ;)
 
If it turns purple, you've screwed up. That's why I grind with bare hands so I can feel the heat and the wheel.
-John
 
Les George said:
cool them off with water as you go, the key to grinding heat treated blades, is when you think you can squeeze one more pass in before you dip the blade - DON'T! ;)
Click to expand...

That makes sense. I've burned my fingers grinding things before - not knife blades, but other parts.
 
skin starts to burn and be consumed at less than 300 deg F. Most steel has a draw temp that is a bit higher than that. ;)
 
One tip is when the blade is getting thinner on the edge use less pressure and passes and dip in H2O more often. Seem the closer I get to the finish of the blade's edge the more excited I get and have been guilty of burning the edge, even though I bare hand grind the blade. When this happens it is time to reprofile to salvage the blade.:eek::mad:
 
When I start my finish grind I cool in water after every pass on the grinder. Its a little overkill but once you get in the habit it helps keep things cool and under control. To answer the original question, I take my finish grind down to a A 45 at which point the blade edge is ground to zero. Sharpen on a norton fine india stone and start doing 1/2 inch hemp rope cuts. If I am still getting good crunching cuts at 200 I go to a piece of hardened steel ( I use the back of my torque wrench ) and do 10 edge flexes. If I don't get any chips or rolled spots in my edge I know my heat treat is in line and I finish out the blade, buff with scratchless pink, and etch in feric cloride to check my hardening lines so I know what happened with my torch work. Every 10 blades or so, or if I start on a new billet of steel I will test to full destruction. This includes chopping antler and bone, stabbing mild steel for tip strength, and 180 degree bends until failure. On average 6 to 10 180's is acceptable for a High Endurance Performance Knife.
 
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