When to heat treat?

[psychophipps]

I was looking at the excellent WIP thread posted by M. Olexey and saw that he heat treats before he grinds his blade edges. Is there any reason why you can't grind your edge and then heat treat the steel to reduce the chances of overheating and ruining your blade?

[Mike Stewart]

I grind Hard - Always have and always will.

I strongly feel that heat treating and tempering the full thickness of steel in the blank will give you the most consistent results.

To me - heat treat and temper are the single most critical steps in getting a knife together.

I'm not knocking any one else's methods.

I think that soak time of steel should be constant so if the edge is thinner and it arrives at temperature first - it is sitting at temperature far longer than the rest of the blank.

The Thinner edge also is quenched sooner that a full thickness blank so it has a different rate of dissipation of heat than the rest of the blank so - it will have a different final structure than the rest of the blank.

The as quenched hardness of a blade is determined by is rate of dissipation of heat.

If the Blank is a different thickness in different places it cannot be uniform.

I might be splitting hairs to some but to me - it is important.

I worry much more about getting the Blank to the stage and structure I want than any chance of overheating it in grinding.

Preventing heat is what Coolant is for.


Mike

[Bill Coye]

I was looking at the excellent WIP thread posted by M. Olexey and saw that he heat treats before he grinds his blade edges. Is there any reason why you can't grind your edge and then heat treat the steel to reduce the chances of overheating and ruining your blade?

You are going to get multiple answers to that question: there are fifteen different ways to skin this cat. It's whatever works best for you (just like everything else in knifemaking).

The handfull of knives I've made were ground to appx 90% completion prior to HT. Feathering plunge grinds and swedge grinds is easier for me as I can finesse the finish better when the steel has been HT.

BC

[SPLITSHOT]

I grind after heat treat. I fell that i get a better finish on a hardend blade. But bill is right everyone does it different...

[RoadFish]

I always heat treated after grind on my 5160 blades because I wanted a differential heat treat with the spine softer. I heat treated my smaller ATS-34 blades before grinding.

[cardoso5fr]

I'm totaly as Bill on that topic. More or less 90% is done before the heat treatment. But if i would use stainless steel, i would'nt may be work as that.

[dfarmerknives]

I remove about 1/3 to 1/2 the total thickness of what I would remove from the blank before I HT. I also only use 1095, O1 and occasionally L6. I also use a smaller grinder that can heat up hte blades too quick, so I have to be diligent on keeping the blade cool.

[Jason Taylor]

I like to think of the meat left on the edge before HT as a protective cover for what will become the final edge. Dip in water as you finish grind and over heating is not a prob.

[PatrickKnives]

I jump to each side, for stainless that I plate quench I will grind to 90 percent, small blades I do after HT or anything I think will warp. Big blades are always ground prior to HT and then touched up.

[Ken Brock]

I initially ground my blades before heat treat but have had much better luck (more consistent results and less warping) by heat treating before grinding

[T.Rexford]

I do all my grinding hard for the reasons everyone else has stated. Consistency, control, no worries about warping as you can surface the entire blank afterwards.

[Michael J. Smith]

I do all my grinding hard for the reasons everyone else has stated. Consistency, control, no worries about warping as you can surface the entire blank afterwards.

Ditto.
Couldnt had said it better.
Plus you can get a lot more blades ready for heat treat in less time if you dont grind before hand.