Thread: Do I really need a lap stone?

Okay. So I will be getting some kind of DMT 320 grit/Coarse. However, since I will probably need something rougher for the Swaty, and I decided I want something a little finer to finish, I stopped by autoworks and got the following: a 3-pack of 3M 80 grit wet/dry paper, a 3-pack of 3M Sandblaster 120 grit paper, and a 4 sheet variety pack of 3M wet/dry paper that I think goes 400 600 800 1000. All of them are the large sheets. I also stopped by Lowes and picked up a marble tile, I laid two of them together and light didn't shine through and it produced suction, so I'm guessing that means its pretty darn flat right? So I plan to use the Sandblaster, as I think 80 is too coarse, but my question is, can I use it wet? No where on it does it say wet/dry, so I wasn't sure, which is why I got the 80 grit wet dry, just in case. After I lap my rocks on the DMT I want to give them a quick run through on the finer papers. Did I get the right stuff?
I found an iron pipe in my garage, can I hit the DMT with that? It looks kinda gunky. Would I be better off going to the dollar store and getting a ****ty knife?

Looking good!
The sandpaper will wear out fast, but if you do the gross jobs on the sandblaster stuff it will work.

No idea on the gunky pipe. Better not probably.

Originally Posted by khaos

Okay. So I will be getting some kind of DMT 320 grit/Coarse. However, since I will probably need something rougher for the Swaty, and I decided I want something a little finer to finish, I stopped by autoworks and got the following: a 3-pack of 3M 80 grit wet/dry paper, a 3-pack of 3M Sandblaster 120 grit paper, and a 4 sheet variety pack of 3M wet/dry paper that I think goes 400 600 800 1000. All of them are the large sheets. I also stopped by Lowes and picked up a marble tile, I laid two of them together and light didn't shine through and it produced suction, so I'm guessing that means its pretty darn flat right? So I plan to use the Sandblaster, as I think 80 is too coarse, but my question is, can I use it wet? No where on it does it say wet/dry, so I wasn't sure, which is why I got the 80 grit wet dry, just in case. After I lap my rocks on the DMT I want to give them a quick run through on the finer papers. Did I get the right stuff?
I found an iron pipe in my garage, can I hit the DMT with that? It looks kinda gunky. Would I be better off going to the dollar store and getting a ****ty knife?

Yeah, you can use the sandblaster wet. It's incredibly waterproof. Much more so than wet/dry paper. It's really different and great stuff, IMO.

Sweet. If I can tolerate it, can I use the 120 for all the hones, or am I better off getting a finer grit sandblaster (ie the 120 will just eat valuable rock)?

Originally Posted by khaos

Sweet. If I can tolerate it, can I use the 120 for all the hones, or am I better off getting a finer grit sandblaster (ie the 120 will just eat valuable rock)?

What other hones are you lapping? I've found that the 120 is really better for heavy duty lapping. I saw you were looking at a thuringian and norton (assuming 4k/8k?). For the norton, I would lap them the first time on the 120 sandblaster, and then subsequent laps on ~600 grit w/d. For the thuringian, unless it's in pretty rough shape, head straight to the 400 w/d, then the 600 w/d (IME, they are soft and lap fast). If it's in rough shape, get it mostly there with the sandblaster, then head to the 600. The idea with the sandblaster is just to get you to an initial flatness and then you should never need it on the same hone again. Once the stone you're working with is flat with the sandblaster, move on up the grits.

I think by the time "subsequent laps" comes around I'll have a D8C. I have not yet decided between the Norton set and the Henckels set, but I guess thats much of a muchness. The Thuringen I'm getting from Kees is in new condition (its vintage though) and he is send it lapped. Good to know that I should only use high grits for it. How high should I go in the grit rating? stop at 600? Or should I smooth out on 800 or even 1k?

I don't think you need to break in the plate for lapping.

Your hones will do that quite readily.