Question about Surgical Black

**brentaar** · 04-26-2010, 01:25 PM

I'm borrowing a surgical black honing stone from a friend, and I've a couple of questions:

I know that this stone has never been lapped, but it has been used. Should it be lapped?

If it can be lapped, would a DMT Extra-Fine be ok to lap this stone, or would i have to use a 8k?

Utopian · 04-26-2010, 03:25 PM

You should not use any DMT hone finer than the 325 grit DMTC for lapping. If you do use a finer DMT plate, you risk undercutting the diamonds and causing their release, thereby ruining your plate.

Regarding whether or not the stone needs to be lapped, it really depends on its condition. Though I would guess that it would probably be helpful to lap it before using a razor on it.

**matt321** · 04-26-2010, 07:02 PM

+1 with the above. Also, add that the black arks are extremely difficult to lap. I have an 8"x3" one and it did not roll over for my XXC DMT. It was a tie. When I gave up, the Ark wasn't completely lapped and the DMT wasn't completely destroyed either.

As has been stated, there are two reasons for lapping these. First, make it flat. Second, make it smooth. Since they are so hard, the texture you leave from the lapping process will affect honing results. So after you get it flat, you still need to use finer abrasives to get it smooth for the best possible finishing performance.

**Shaman** · 04-26-2010, 10:05 PM

I am in the process of lapping a surgical black so I'll share what I've learned. These stones are so hard that I wouldn't even try to lap it on my D8C, if I had a XX coarse maybe. It wore out a sheet of 220 wet/dry getting just one side of this thing flat. Ater that I'm lapping on progressive finer grits, 400, 800, 1000 to smooth it out. This part is not nearly as tough as getting it flat in the first place but it is still a chore. BTW, I'm lapping a C12K too and in comparison the C12K is like lapping a norton 1K waterstone. Good news is it will probably never need to be lapped again in your lifetime.

**rwb** · 05-09-2010, 02:24 PM

sham has it right , they are a bear to lap then work it up in grits to the finest grit you can get, i took mine to 2,000 grit then worked it on a 8,00 grit stone and it is a fine finisher now.

**Shaman** · 05-10-2010, 11:49 PM

Originally Posted by rwb

sham has it right , they are a bear to lap then work it up in grits to the finest grit you can get, i took mine to 2,000 grit then worked it on a 8,00 grit stone and it is a fine finisher now.

What kind of stone did you use? I've thought about using my norton 8000 water stone but don't want to wear it out until I've got something to replace it with.

**rwb** · 05-13-2010, 04:45 PM

the norton would be good it doesent take that much when it has been laped to 2000 paper you can tell when it gets glass like smooth

**kwigibocity** · 05-13-2010, 08:11 PM

I've lapped many customers Arkansas stones with the Duo-Sharp X-coarse/coarse 10x4", which DMT considers their purpose-built lapper. It actually works much better than the XX Dia-Sharp. Many stones in the books and it isn't even that much of a battle. It is one truly exceptional lapping device, though I've never had the pleasure of using the Shapton DGLP.

Utopian's absolutely right, the DMT "C" is their highest-grit recommended for lapping. I have used an "F" DiaSharp, but wouldn't advise it to anyone.