Rookie Question on Blade Finishing

F

Fixed Blade Fever

Joined
Nov 23, 2005
Messages
50
I just acquired a new grinder (Bader BIII with VS), which some of you guys advised me on a about a month ago. It is a great unit and I spent a few days welding a nice stand for it.

I just ground my first two blades (D2)and finished them to 220 grit. I was really pleased with the way they turned out for my first try. Since I live within two miles of Texas Knifemakers Supply, I took the blades there for heat and cryo treatment. When I got them back from TKS, I began to regrind the blades to remove the dark grey burnished look that apparently is a by-product of the heat treatment and prepair them for final finish and handle application. My intent was to start with 220 and finish with a 400 grit belt, then a light buff after that. However, the dark grey appearance seems to be burnished deeply into the steel and I do not seem to be able to grind it all away. Unfortunatly, at this point, I have removed a lot of stock trying to remove the gray mottled color, and now the blades are much thinner than desired. I have resorted to hand sanding with 320 but do not seem to be making any progress. I know that you have to break a few eggs to make an omlet so to speak, but it is a great dissappointment to have somewhat ruined the blades as I was real happy with the way they turned out before heat treat.

Any ideas on what happened? Any tips on either how to get rid of the what remains of the mottled gray appearance on these blades, and also how to avoid this problem in the future?

Your help would be greatly appreciated.

Thanks
 
If I remember from my D2 days they dont ever take a high shine. You can acually see the carbides in D2.
Next time maybe choose something like CPM154 that takes a mirror finish.
 
Bruce, the blade had a normal appearance before the heat treat, should it look different afterwards? I understand what you are saying about the D2 not being good for a mirror finish, but unfortunatley, I am not even close to the mirror stage yet. The grey color that I can't seem to get rid of is splotchy and some areas appear somewhat normal.

Howie, overheating could be a possiblity, but I was holding the blade with bare hands while finish grinding and it did not feel like it was getting that hot. Although It did feel a bit warm a few times, but not hot enough to put down. Is that too hot?

It definitely looks to either be overheated or just that the gray color from the heat treat is burnished so deeply that I don't have enough meat left to grind away the burnished layer. Maybe that is the problem and I did not leave enough extra beef on the blade to grind off enough of this layer to get to clean looking steel.
 
Probably not overheating or high surface heat in grinding, then.
I'm sure you told them it was d2 when you sent it for HT...?
 
Welcome to D2 and vanadium. Take it to 400 grit prior to heattreat next time and try gator belts after heat treat. Take it slow (like it will give you a choice) and keep it cool. Anything with vanadium like D2, BG42, or S30V should be taken closer to end finish prior to heat treat. 220 would be ok for most other steels.

For polishing D2 the trick is to start with heavy black rouge on a sisal. Use ALOT of rouge. If you don't it will orange peel. Then with the same sisal switch to green rouge. Again the primary trick is to use ALOT of rouge. Recharge very frequently. Switch to a sewn muslin with green applied very frequently. Finish with an unsewn with a fine rouge like pink diamond. You will get as close to a mirror finish as possible with D2. If it orange peels or gives poor results you didn't use enough. You will be surprised at how well D2 can polish with the right technique. It won't compare to 440C but it can give better results than some believe.

Dont forget the safety hazards of polishing, particularly with an unsewn.

D2's visible surface structure is very unique. What you are seeing may be the normal surface of D2 after heat treat. Post heat treat does look different than pre heat treat on D2.

Tim
 
Howie, I did fill out a form when I left the knives for heat treating and if I remember correctly, there was a box to check for the type of steel to indicate it was D2.

Tim, I have some gator belts on order as well as a pyroceram platen liner that I will try next time. I will also try finishing to 400 before heat treating the next blades.

Thanks for all the help guys.
 
Next time don't leave any stock to remove after heat treat. Just finish grind. Start with a new 220 grit and work up to 330 or 400, then hand sand.

Always use sharp belts. Your problems sound like the results of using worn out belts to me.
 
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