Thread: Lapping Plates - Glass or Granite or somthing else?

I have both a glass lapping plate and a granite lapping plate but what is better?

I would have thought glass would wear less but in the wood working shop around Perth they only sell granite plate with a certified accuracy.

I would also like to to say, the granite plate that i have with its certified accuracy of 0.0001" is not that accurate! lol i chucked my certified DMT plate on it and a ruler and it had sections where light was visible. The glass plate is also slightly out (I'm using a 6mm thick glass chopping board) but not my too much

I have now lapped the granite plate with my certified DMT, not as hard of a process as i was expecting but i guess it was only slightly out.

I then chucked a stone and lapped it on the granite plate with a 600 grit powder and it turned out extremely smooth and flat and very quickly! My glass plate would have left scratching in the stone still i think...

So will granite be as hard wearing as glass or is glass longer lasting, is the granite more accurate or would glass be just as good or more accurate. Which would be better for lapping in general?

Thanks!

as long as the plate is flat enough, it does not matter what the material is. Micron accuracy is not needed as long as it is reasonable accuracy.

but if i can lap the granite flat with a DMT is this going to cause problems with wearing when lapping? Basically, what i want to know is, should i be using the glass for most stuff and finish on the granite or with the granite be fine for anything and everything?

Who on here uses granite and who uses glass and what are your thoughts on the subject?

Now that i have started using lapping plates i don't think i could go back to sandpaper lapping, the powders on the plate are so much faster at lapping! I just dont want to lap a few hard stone with my 90 grit powder and end up with a granite bowel and need to flatten the plate after X amount of laps

Wait i think I finally understand what you are saying. You do not lap with the granite, you put sand paper on it and lap on the sand paper.

How did you come to the idea to lap with the granite or glass plates in the first place?

A few of the guys on here lap with the granite or glass using the lapping powders.

The granite plate I purchase is sold specifically for lapping powders. If you haven't tried it, look into it as its a great alternative to sandpaper.

This is the plate I got. Granite Surface Plate : CARBA-TEC

Why use the lapping plate if you have a DMT?