Thread: Lapping Shapton w/ DMT D8C

Really.. hmm when I was lapping them I noticed that I could look at the shapton from the side and see a low spot near the middle where it curved downward.

Originally Posted by Howard

The reason Shaptons are so exceptional is the diamond composite and that they're so flat to begin with and that's what you're really paying for with that stone. I have used a GDLP on Shaptons as that's part of the Shapton system. When you have something that flat, a rock solid holder is necessary to keep it flat and the lapping stone should be consistent with the technology. The Shaptons start out two orders of magnitude flatter than a DMT which is +-.001" across the surface. The Shapton is .001mm which is a whole heck of a lot flatter. I've been playing with Shaptons (with Harrelson Stanley) lately as I'm going to be carrying them in a couple of weeks.

Ah ha! So Howard's been bit by the Shapton bug as well. As Christian (Kaptain Zero) says...resistance to Shaptons IS futile!

Originally Posted by bevansmw

Really.. hmm when I was lapping them I noticed that I could look at the shapton from the side and see a low spot near the middle where it curved downward.

What Howard means is the Shapton GDLP lapping plate is .001mm flat across its surface. The Shapton ceramic on glass stones are not pre-lapped and vary in factory flatness or lack thereof. Don't worry about how long it took you. You're there and can enjoy the stones. It depends on how much pressure you use when lapping. On a few of my Shapton ceramics I laid them on my GDLP and literally just used the weight of the stone to lap. It took as long or longer than it did for you.

Now when I touch up (which I do for each stone before each lapping session, I just rub the stone and GDLP together lightly under running water for 10-20 circles to remove the steel swarf. It only takes less than 30 seconds.

Enjoy those Shaptons!

Chris L

That makes sense. So the DMT is about .025mm (= .001") flatness and GDLP .001mm, so the question is 24 thousandths of a mm really perceptible?

Edit: Maybe makes more sense in terms of micrometers, 25 micrometers flatness vs. 1 micrometer. I don't think that is much noticable, though 25 times greater it's still exceedingly flat.

Originally Posted by bevansmw

That makes sense. So the DMT is about .025mm (= .001") flatness and GDLP .001mm, so the question is 24 thousandths of a mm really perceptible?

This flatness argument, especially the DMT vs. Shapton GDLP has been around for some time. My opinion is summation is:

There is absolutely no direct SHAVING advantage from the Shapton stones being lapped to .5 micron versus the DMT lapped stones to .001". None. Skin is pliable and conforms to a keen shaving edge. So....zippo, no advantage on this front.

HOWEVER...............There IS an advantage (the degree of which can be debated) to having each honing stone in the grit progression used being .5 micron flat vs. .001". Less surface variation or greater flatness from stone to stone makes for faster removal of the prior stone's scratch pattern. If I hone a razor that lies flat as it should on both sides of the blade, I've found that it takes less passes on the finer grit stone to remove the prior stone's scratch pattern since I've been using the GDLP rather than the DMT. I attribute this to the flatness factor.

With that said, are we talking about a world of difference in time? Does the DMT's flatness at .001" mean the DMT can't do the job as a lapper? Of course the answer is no on both counts.

There are so many areas of interest in life where those that are deeply interested and even obsessive about an interest will debate the most minute points of the smallest advantage of one thing over another ad nauseam. It's no different with us.

I like my GDLP and think it's great. Not only for it's flatness but also for it's non-continuous surface which reduces stiction. That said, I would never advocate that DMT is crap and everyone should drop a big chunk of change on the GDLP. Both will do what they're supposed to do. The GDLP is there for those of us find an IDEAL is worth spending $280 when we all know or should know that spending a lot less on a DMT is just fine.

Just my 2 cents. One more thing to add; I don't think anyone who buys or is contemplating buying a DMT D8C for lapping should ever feel they'll NEED the GDLP at a later date. There's nothing wrong with DMT.

Chris L

Originally Posted by bevansmw

That makes sense. So the DMT is about .025mm (= .001") flatness and GDLP .001mm, so the question is 24 thousandths of a mm really perceptible?

Is it really perceptible? Yes! If you mean when sharpening razors, then no. I think we keep forgetting that Shapton hones were never designed for straight razor sharpening.... I bet the folks at the factory are downright amused at this newfound source of customers! Back to the flatness issue... when honing bevels on traditional Japanese planes and bevels on chisels and the like, flatness really does matter. The larger the bevel, the more material needs to be removed and the longer it takes. If one hone is slightly dished and the next finer grit is the opposite, it can take a loooong time to polish that bevel if you are up in the 4k 8k and beyond grits as they really don't remove much material. On the other hand, hollow ground razors are much less affected by such trivial flatness errors such as 0.001" so that it would not be noticeable at all. I seriously doubt it would be noticeable on a wedge for that matter. And while we are at it, DMT claims 0.001" max variation, NOT that it WILL be 0.001" out of whack. Ditto for the Shapton unit... the differences between any two samples will vary.

There is a secondary and much larger issue is the ability of the operator to flatten the hones with these plates.... The correct way to compare the two would be to measure the difference on the flattened hones and not the diamond plate used to flatten them. If one constantly turns the hone end for end while flattening, using the full surface of the diamond plate, the effect of a .001" bump or hollow would not be measurable on the hone that was flattened, particularly when you consider the water and slurry between the two items in use having it's own moderating effect. I personally would not expect myself to do better than 0.001" with either diamond plate.

HAD is a frightening affliction though, it really can mess up a gents mind to the point that a $250+ diamond flattening stone starts to look like an irresistible good deal and is sure to shave years of honing time off the next time you have to touch up the edge of a straight razor..... I should know, I'm fighting the urge to order one and I'm not winning! I mean... they look so damn cool!

Regards

Kaptain "Who said logic and common sense had anything to do with the hobby of straight razors?" Zero

Like Chris said, there is nothing wrong with a DMTC for lapping. And like Kap Zero said HAD is a helluva affliction So I have both the DMTC and the GDLP. It reminds me of one of those motorcycles that is built for both road and dirt. It will do both but not as good as a dedicated sure enough road bike or dirt bike. The DMT is made for sharpening. It works for lapping and if you don't mind the stiction it will get the job done but the GDLP is to lapping like a Husquvarna is to riding dirt. It is made for it and does a superior job IMO.

For the record, I lapped the 4 Shaptons that arrived in the mail today on my D8C and I had zero problems. Total time was about 15 minutes including cleanup which was about the same as when I did my Norton 4k/8k.

I'm really torn now about the DGLP. Doing the math on the difference between the DGLP and the D8C in regards to accuracy tells me the DGLP is not worth it. On the other hand, the DGLP looks really cool, will have less stiction and did I mention it really looks COOL. To be honest, the D8C is fine for flattening not only the usual hones but the Shaptons as well. The only thing in my crazy world that does not make sense is HAD and I've got it.... big time!

Regards

Kaptain "I'm as broke as the last hone I dropped on the basement floor" Zero

I did end up having a bit of a problem. My hones that I lapped feel really smooth after lapping them, I tried setting a bevel on one razor last week and noticed no swarf was coming up at all and I was getting a lot of stiction, the razor was like a vacuum to the hone. I e-mailed one of the guys at shaptonstones the other day asking about it as I got a little worried that I had managed to take off all of the ceramic, he said it was unlikely and I probably just smoothed it out while lapping, said the GDLP helps to preserve the sharpness of the ceramic while lapping so it isn't smoothed out. I think I may end up buying a GDLP now just to make sure

Unless someone with a gdlp wouldn't mind me mailing the stones to you to have them lapped ? I could pay both ways shipping and that, just to make sure it will restore the sharpness to the stones.