Heat Treat Then Start the Grind?

I grind 95% of my knives after heat treating them. I don't feel that one method is better than the other but post ht grinding works for me.

If I am going for a hamon or with a shallow hardening steel I usually grind before heat treat.




Why I grind post heat treat...

I like the way the steel grinds, I feel I have a bit more control with hardened steel

It almost eliminates any warping problems and makes them much easier to correct during and after heat treat.

Less steps to a finished blade...

It often isn't much tougher to grind hardened steel especially with decent ceramic belts running fast.

I get full plate contact when plate quenching air hardening steels

...works better with the folder making process.


Either way works great though! It really is a tossup and all depends on your style.
 
I have learned that the biggest pain in my ass in the world is blade finish. Grinding a soft annealed blade so beautifully, getting it back all blue and grey from the heat treater, sticking the blade back onto the grinder to clean that crap off, and ending up with a completely different blade shape than what I wanted. I have "ruined" dozens of blades this way. I eliminate all expectations when I grind hard. It feels like I'm grinding them the way I want the first time. It's psychological for me.

I get what I want out of my blades the first time around, and the processes don't seem so backwards when I grind a blade hard.
 
I grind all my blades 1/8" or less after heat treat.which is % 80 of my blades. The lines are so much cleaner. The belts go faster, but they can still be used for profiling or handles.
 
I grind 98% of my blades after HT. That's stainless of 1/8" or less in thickness The other 2/100 are carbon Damascus blade. and I grind then HT those.

Like Josh just mentioned, I get what I want the first time. I use Ceramic belts and only get one knife per belt then it's used for profiling or other work. So a sharp new Ceramic belt on HTed CPM-154 or S35VN helps keep the temp, down, Then I dunk after each pass and work my way from 36G to 60G then 120G then A/O, cork and Scotchbrite belts for finishing.

Heat is the enemy! As long as you keep the steel under about 200-250 degrees "Boiling water" you will not have any problems.
I only wipe the side I am grinding after each dunk, I watch the water beads as I grind and as soon as they start to boil its back in the bucket.

Try it! You'll like it!
 
Rhinoknives1 said:
I grind 98% of my blades after HT. That's stainless of 1/8" or less in thickness The other 2/100 are carbon Damascus blade. and I grind then HT those.

Like Josh just mentioned, I get what I want the first time. I use Ceramic belts and only get one knife per belt then it's used for profiling or other work. So a sharp new Ceramic belt on HTed CPM-154 or S35VN helps keep the temp, down, Then I dunk after each pass and work my way from 36G to 60G then 120G then A/O, cork and Scotchbrite belts for finishing.

Heat is the enemy! As long as you keep the steel under about 200-250 degrees "Boiling water" you will not have any problems.
I only wipe the side I am grinding after each dunk, I watch the water beads as I grind and as soon as they start to boil its back in the bucket.

Try it! You'll like it!
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What's A/O? Aluminum oxide belts? I use norton blaze and some other micron belts that go all the way up to 3000 grit. I then have the leather belt for compound. I should probably get me a scotch brite belt but I don't think I really need it. Thanks, I will try it! Gosh, it's like you can never have everything that you need! Lol.. The list just keeps growing!
 
otpowell said:
What's A/O? Aluminum oxide belts? I use norton blaze and some other micron belts that go all the way up to 3000 grit. I then have the leather belt for compound. I should probably get me a scotch brite belt but I don't think I really need it. Thanks, I will try it! Gosh, it's like you can never have everything that you need! Lol.. The list just keeps growing!
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60 grit Blaze. 180 grit gators and a fine green scotchbrite belt. You wind up figuring out that you don't need that much. Thats basically all I use to make the knives I want to make. You should see all the crap I have bought because I thought I had to have it. It's all in a toolbox collecting dust.
 
otpowell said:
What's A/O? Aluminum oxide belts? I use norton blaze and some other micron belts that go all the way up to 3000 grit. I then have the leather belt for compound. I should probably get me a scotch brite belt but I don't think I really need it. Thanks, I will try it! Gosh, it's like you can never have everything that you need! Lol.. The list just keeps growing!
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Yep! you have it. I don't use all of that for every knife. It depends on how I want the finish to be at the end.

Most are a 36G 60G 120G and then the Brown, Maroon and Blue Scotchbrite for my satin finish.
Not every belt works for everybody. I have never been happy with the finish I get with the structured belts from 3m or Norton. Other love them.
You will find your own system after experimenting with a few different kinds of finishing belts that will get what you like in the shortest time.
 
HT before grinding would also facilitate accurate HRC testing, without leaving a mark... so long as you don't overheat during grinding.
 
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Dang. I really learn something (or 10) new every time I check these threads.

I *never* would have suspected that so many (or any) of you ground your blades after ht.

Thanks to the op for asking in the first place. I believe I'll give this a go. My only experience post ht has been with d2 and all by hand. Not very fun.

@DF, I'm surprised by your method. Your grinds are so nice, and I may have specific questions, but I'll put them in the q&a on your forum.

@IanHall, nooo! Stay with your big hollows! So very pretty and classy. At least keep them as an option until I've had a chance to grab a few. :)
 
Josh Mason said:
60 grit Blaze. 180 grit gators and a fine green scotchbrite belt. You wind up figuring out that you don't need that much. Thats basically all I use to make the knives I want to make. You should see all the crap I have bought because I thought I had to have it. It's all in a toolbox collecting dust.
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No kidding? This info is priceless and I appreciate it! Thank you!
 
I finished grinding my latest blade this weekend. I heat treated with the edge around .05-.06 and ended with the edge at 0.015. I probably spent as much time grinding post HT as I did pre-HT. I think I'll start thinning down the edge a little bit more pre-HT.
 
I sent my knives to Peters with a .015" edge. .25" 52100 and all 50 came back straight as an arrow. I did another 35 out of .187" 52100 with a .040" edge and same result. I leave ht to the experts.
 
Post Ht for me. Long, thin and tapered carbon steel kitchen blades move too much for my liking to grind before. I grind sand mia blades with a soft cladding after ht because the bends, dips ect are easier to fix than a fully hardened blade.
 
I grind all my blades ( d2 steel and CPM S35VN ) to almost 95% finish and send it to a professional heat treat company for vacuum heat treatment. The remaining 5% if for finishing ( bead blasting and cerakote ).
 
aarongough said:
Agreed that hollow grinds are more sensitive to warp, I hadn't thought about that as a factor in the discussion though, good catch!
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I'm definitely still new, but I've done enough now where I'm starting to at least form some decent idea of what works for me and the HT place I use. I had a decent conversation with my guy about how the finished result depends on how much he is able to work with the maker, he has guys send in some really crazy stuff and then get upset when it comes back warped.

Mark Behnke said:
I only hollow grind and have lost a lot of blades to warp recently, going to thin .020 at edge before HT.
Going back to .030 to .050 and see how that works.
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Exactly the same experience I had.

my first blades were about .040-.050 out of caution, and then I went down to .03 and had success. I did another batch with one at .025, one at .023, and one at .02, and the one at .02 was lost, .023 was barely saveable, and the .025 was passable but not great.

I think .03 is my lower limit now, for hollow grinding at least. It takes a few minutes to bring them down to final, but it just really isn't that bad for me with a new belt and plenty of dips in the water bucket.

edit: I actually have had decent luck with thinner edges, but only on narrow knives when the hollow grind isn't that deep as far as the wheel radius/grind width ratio. I think the slim wharncliffe I did was .02 in 1084, and it came back straight as an arrow. It was also only about 3" long and .75 wide, not really much room to warp in. I probably could have ground that one after HT just as easily, so maybe it is a moot point.

Strigamort said:
@IanHall, nooo! Stay with your big hollows! So very pretty and classy. At least keep them as an option until I've had a chance to grab a few. :)
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No, I'm still gonna do hollow grinding, but I will probably start doing large radius hollow on at least part of my knives. I like flat, but it's really popular and I feel like there are plenty of superb makers doing that grind already (with good reason, it's a great grind engineering wise, and can look amazing).
 
95% of my knives are ground after heat treat.

If I'm going for a hamon, I'll obviously grind the blade prior to heat treat.

Grinding after heat treat greatly reduces any chance of warp, and saves time IMO.

Keeping the blade cool during the grinding process is easier than most people think.
 
Mitchell Knives said:
95% of my knives are ground after heat treat.

If I'm going for a hamon, I'll obviously grind the blade prior to heat treat.

Grinding after heat treat greatly reduces any chance of warp, and saves time IMO.

Keeping the blade cool during the grinding process is easier than most people think.
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Like alot of processes in knifemaking, it always sounds scarier than it really is.

Keep your water bucket handy, squirt a good amount of dish soap in there to keep from flash rusting if you're using carbon. Use your bare hands to feel the heat in the blade. Watch the water droplets on the backside of your grind. If they start to bubble and evaporate, dunk it.
 
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Personal experience working with thin (.095) stock 52100 and 15n20 with of 61-63 ish hardness.

I grind the bevels post HT (chefs knives). Even post HT the blade can bow on you due to the stress risers created by grinding, irrespective of how cold your blade is. When i notice the piece developing a bow, i'll flip it over in the jig and grind the opposite face. From what i gather, this "evens out" the bow by creating stress risers on the opposite face. When I'm satisfied that its is true, I'll move up ti the next grit and repeat the process.
 
I've done both.
On larger and thicker blades, I'll typically do a fair portion of grinding before heat treat. On smaller and especially thinner knives (1/8" or less) I'll usually heat treat first, especially if I'm doing a scandi grind. That said, I will often bevel the corners pre-heat treat. I also make sure that I use sharp belts and dip on every pass or two if grinding after tempering, so that I don't raise the temp of the steel above tempering temps.

FWIW, I've had blades warp when grinding before OR after, just as I've had blades stay perfectly straight ground before or after. Thinner blades are easier to straighten unground, if needed, IMO.
 
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