Grinding after HT

Y

yessahmassah

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Sep 22, 2015
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I finished my first knife a month or so ago, and am looking towards my next project. I heat treated after the knife was pretty much done, then cleaned it up, and put the handles.

I have 4 blanks I was able to get from a piece of O1 and I want to try HT then grinding. I did my first knife with a file jig and a 1x30 HF belt sander, which actually works better than I thought it would.

I do remember over heating the metal though. Mainly around the tip. How do you avoid this if the knife is already heat treated? I know quenching it in water will help a lot, but what techniques should I look at to make sure I don't over heat it?
 
Just make 2 passes and dip
Make 2 passes and dip.
Don't think " I can make one more pass real quick" and you should be fine.
 
I grind most of it before, but leave a bit to grind off. I usually full flat grind, and before HT I leave it so that I have maybe 1/4 of the bevel unground (1/4 of the way from the top, I mean) and the edge about as thick as a dime. I grind the rest after HT, right down to a zero edge. Go slow, dunk often. Use bare fingers and you can tell real quick when it's too hot :). You don't want to do a lot of hogging of material after HT; you'll just be wasting belts and generating a lot of heat.
 
I really think that VS on the grinder is the most important part of post HT grinding. The very best setup is a wet belt system. An uncontrolled 1X30 will have to be carefully used and the blade dipped every pass or two. Be cautious where the blade gets thin, which is at the edge and tip.
 
Until I started forging, I ground all my blades post HT. There's already been some really good points made; I have one (or two) more. How much grinding you can do between water dips depends on the conditions. If you are doing a big chopper and just starting to grind in the bevels, you can grind for quite a while compared to putting the final 400 grit on the tip of a thin slicer. More steel can absorb more heat before getting too hot. It's also important to know which direction to grind. If you are doing finishing passes, the tip is going to be thin and cannot dissipate much heat therefore, you don't want to start a pass at the plunge and work toward the tip. The heat buildup will be too great. If you start at the tip and work toward the plunge, the blade can soak more heat as you move into thicker metal.

I also think dunking frequently teaches you how to put the blade back on the belt more accurately so there's an added benefit.

Bob
 
That 1x30 from HF runs too fast if you don't have a lot of experience and skill to finish grind. The platen it comes with is not flat and has chatter. If you apply a lot of pressure you are going to heat the blade almost instantly.

You can make our own platen like I did when I first started out for it, it's pretty easy. For most of us with moderate skill we still need the slower speed for finish grinding, especially the tip. You don't want to overheat the blade before or after heat treat.
 
Over heating the blade and damaging the HT is far more common that people think . So check out wet grind systems and use that !!
 
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