Grinding help please.

[J. Hoffman]

Hi everyone, I started some knives in CPM D2 and I'm having an issue. I'm very new to making knives and I've used my flat platen to grind the mill finish off of my knives after I have shaped them. I use a welding magnet to hold the blade while I push it into the belt. I alternate the blade direction so that it isn't always grinding the same direction and I use what I believe is even pressure on the whole blade. My problem is that I seem to be getting "pockmarking" that never gets ground away. I believe the pockmarking is just mill finish. My blades are getting thinner than I want them to be and the pockmarking is still there. I've been using Dykem to see where I'm grinding and the pockmarks are still there. Am I doing something wrong or does it take that much grinding to get all that mill finish off? I'm using a 36 grit at about 80% speed on my grinder.

 

[AVigil]

Chances are your blade is not perfectly flat and when you are grinding you are removing material on either side but not at the apex.

What I do is cover the surface with dye chem or sharpie and grind it flat first before grinding the angles. Once flat I then profile and continue with the blade.

One benefit of buying your flat stock ground is you do not have to deal with that so much.

 

[J. Hoffman]

Thanks Avigil. I guess is there anything I can do at this point or do I just keep grinding away? Aldos ground steel was looking tempting the last time I ordered, I guess I'll have to try it. Either that or get a surface grinder attachment

 

[AVigil]

As long as that is there it is not flat.

Sorry but you have to grind that down until smooth.

 

[galadduin]

Thanks Avigil. I guess is there anything I can do at this point or do I just keep grinding away? Aldos ground steel was looking tempting the last time I ordered, I guess I'll have to try it. Either that or get a surface grinder attachment

Or you might try to straightening the profile, with pliers on a vise...

 

[logem]

That kind of looks like inclusions in the steel. Perhaps you'll never get it ground away because it may be a bad bar of D2?

I've never had a problem like this, except on a bar of ATS-34 that I received a long time ago.

It' hard to tell from the photos, but I can't see how you would add that type of pitting when trying to grind the profile flat.

Mike L.

 

[WilliamWoods]

All you need is a glass platen and some JB weld. The glass platen is a cheap and durable fix for a grinding surface that is not quite "true". This is a $20 fix.

USA Knifemaker carries them.

 

[Robert Carter]

Cpm d2 is a pain in the ass to work with maybe start out with something a little easier. 440c or 154cm are easy to work and there quality steels.

 

[WilliamWoods]

Cpm d2 is a pain in the ass to work with maybe start out with something a little easier. 440c or 154cm are easy to work and there quality steels.

Your right CPM-D2 is no walk in the park to grind but if his equipment is out of spec then it wont matter if he tries a more grinder friendly steel.

 

[james terrio]

I'd be pretty surprised if those were actually inclusions in CPM-D2, I think you're right and it's just from rolling. How many thousands have you taken off the bar so far? It can take several thou of grinding on each side to get past the pits, even on high-quality steel like you have there.
Just get the piece as reasonably flat as you can. I think I would go ahead and start the bevels/tapers and see if you get past those pits.
Aldo and I have an understanding - whenever I order steel he doesn't have to ask if I want it flat-ground. Just go for it. Think of the time and belts you would have already saved