Does anyone lap with a synth hone instead of a diamond plate?

[kohalajohn]

I'm pondering this as I'm about to buy a Shapton progression and a jnat finisher, and want to maintain them well.

Currently I use my Atoma 400/1200 diamond plate for lapping. But it's pretty new and even the 1200 seems rough.

Would it be better to maintain things with a gentler system? A mid range synth hone would leave a smoother surface, which would be good.

I have an old pair of 3k and 8k synthetic stones that I could use for this. I keep them flat with the atoma 1200.

Trying to lap with a grit finer than the stone you're trying to lap would be very slow. The Shapton 1k would giving more lapping to the 3k synth that it would be receiving. And the Shapton 4k would be about equal. I would have to do this every single time I used the Shaptons or the Jnat.

I'd have to use a pencil and check for dishing every now and then. If it was dishing, then fine, I'd use the diamond plate to get it flat again.

I can see the problem that would arise with this. Over time the razor dishes out the middle of the hone. And as I try to "lap" the hone with a synth that is a finer grit than the hone, the hone would aggressively impose its error on the fine synth until the fine synth agreed with it. The high shoulders around the hone would grind away the fine synth, creating a convex synth. So now the convex belly of the fine synth would perpetuate the dish error in the hone.

I suppose one way is to lap with the 1200 diamond plate and then smooth the surface with the 3k synth. But then, if I am willing to do it every time, why not just the 3 synth by itself? You'd think that say 20 laps of a 3k synth could undo whatever little damage that 50 laps of a razor had done.

Maybe the fancy way is to use the Japanese "three stone" method of lapping. I'd use my Shapton 1k, 4k, 8k in that way.

Thoughts?

 

[buca3152]

1200 atoma imo is fine enough to finish for sure. I used to play around with various stones to get a finer finish on the base stone. What I found that worked very well was a bbw side of a.coticule. But at the end of the day I found it didn't do anything to improve the edge. Imo anyway.

 

[Luecke2326]

The 400 Atoma does the trick for me, before that, a coarse DMT. My edges are great, just don’t bear down on them.

 

[stone and strop]

Atoma 1200 plate is good for everything, plenty fine enough.

 

[Gamma]

Lap in the sense - remove a lot of material to level a stone for the 1st time or after a beating - no.
Lap in the sense of giving a working surface a finer polish - I have, yes.
I've also used other naturals - like a Coti, BBW, Jnat, etc - for the same purpose.
Thing is - even with a good rinsing, any given stone could leave contaminate/particulate behind and it could possibly get in the way later on.
I don't often polish any stone's working surface past 600x w/d so my Atoma 400x fits the bill nicely.

 

[kohalajohn]

The Shapton faq says that you can lap the shapton glass stones via the three stone method.

I'm about to receive a Shapton 1k, 4k and 8k. The old three stone method would suggest that I lap stone 3 to 1, then 1 to 2, then 3 to 2 and just keep going.

I agree I'd have to be careful to wash them clean after. But that applies to new diamond plates as well.

I'll just see how it works. Just curious.

 

[H Brad Boonshaft]

Lapping to dead flat is overrated for razors and a waste of stone. Why is it that the Japanese are not dead flat obsessed with naturals?

Lap a new stone flat, to remove any valleys so the surface is consistently smooth, after that lap to refresh the surface and remove swarf.

A lapped synthetic stone will go out of “perfectly flat” after the first couple of laps, but it does not matter the razor will just ride on the high spots. A razor’s bearing surface is what, a 1/16 of an inch wide? How flat does it need to be?

I refresh lap with a 400 grit Atoma and my 8k Snow White leaves near mirror finish and super straight edge.

How do machinist get to flat? Grind on a diamond surface grinder, how flat is a diamond surface grinder? It is not, it is a wheel.

 

[JPO]

I'm pondering this as I'm about to buy a Shapton progression and a jnat finisher, and want to maintain them well.

Currently I use my Atoma 400/1200 diamond plate for lapping. But it's pretty new and even the 1200 seems rough.

Would it be better to maintain things with a gentler system? A mid range synth hone would leave a smoother surface, which would be good.

I have an old pair of 3k and 8k synthetic stones that I could use for this. I keep them flat with the atoma 1200.

Trying to lap with a grit finer than the stone you're trying to lap would be very slow. The Shapton 1k would giving more lapping to the 3k synth that it would be receiving. And the Shapton 4k would be about equal. I would have to do this every single time I used the Shaptons or the Jnat.

I'd have to use a pencil and check for dishing every now and then. If it was dishing, then fine, I'd use the diamond plate to get it flat again.

I can see the problem that would arise with this. Over time the razor dishes out the middle of the hone. And as I try to "lap" the hone with a synth that is a finer grit than the hone, the hone would aggressively impose its error on the fine synth until the fine synth agreed with it. The high shoulders around the hone would grind away the fine synth, creating a convex synth. So now the convex belly of the fine synth would perpetuate the dish error in the hone.

I suppose one way is to lap with the 1200 diamond plate and then smooth the surface with the 3k synth. But then, if I am willing to do it every time, why not just the 3 synth by itself? You'd think that say 20 laps of a 3k synth could undo whatever little damage that 50 laps of a razor had done.

Maybe the fancy way is to use the Japanese "three stone" method of lapping. I'd use my Shapton 1k, 4k, 8k in that way.

Thoughts?

I lapped my shapton gs 0.44 with an 2k soaking ceramic stone once. When i used it the next day it seemed like some of the 2k grit was stuck to the stone. If you use a different brand, with a different binder you can get an reaction if you do not rinse properly. I have a set of vitrified diamond stones that seem to work fine, but i only use them for surface conditioning.
I am still not sure how to lap my higher grit shaptons without compromising the surface to much. They are not used much, but if i use them i rub my 0.85 with my 0.44 gs. This seems to be enough to keep them flat.

 

[Empire straights]

I use a coarse SiC stone to rough up the surface on stones sometimes and a fine India to smooth them out if too rough.