Thread: What Shapton DGLP Confirmed!

I finally finished off my 10 stone set of Shapton's with the 220, 500, 1k, 30k and also the Diamond Glass Lapping Plate (DGLP) over the last month or so. Today I decided to lap the new ones and clean and chamfer all of them. I started with the new 500 and it lapped in just a few minutes and was barely off from being already flat. I thought how lucky, because all my stones, Shapton, Naniwa, Norton, coticules, PHIG, WHIG, etc. have always been high in the middle and required a fair amount of lapping with the DMT325/DMT8C. I've used the same DMT for all of my lapping over the past 6 or 7 months and its been a good system, maybe? Next I lapped the new 1k and it needed even less lapping with the DGLP than the 500. Both of these stones had a pencil grid. I was going to only clean/light lap the remaining stones since all had been lapped with the DMT325 and had only been used on one razor since lapping. Instead I decided to pencil grid the 2k and lap it with the DGLP (which is rated to within 5 microns of flatness) just to see. It was immediately obvious that it was now low in the middle and high on the ends. It took a fair amount of lapping to flatten it. Accident? Put a grid on the 3k with the same result and so on 4, 6, 8, 16, and 30k all were low in the middle and high on the ends and had been lapped with the DMT. I had kind of checked the DMT before, but not really close because I really thought it was true. I wish I still had my milling machine so I could level the DMT on the table and chuck up a feeler gauge, but of course I sold it a few years ago. So not having a way to really gauge it I laid several of the Shaptons that I had just lapped on the DGLP on the DMT and each-very slightly-rocked from end to end. I can only guess, but I would say the middle of the DMT is off by several thousandths of an inch. Anyway, if you're using a DMT and find all of your new stones are high in the middle, I'd check the DMT first. I'm not knocking the DMT's I've recommended them many times, but I guess now and then a black sheep can always get out of the pen. Now I've got to re-lap all the other stones!!

Regards,

Howard