Thread: Lapping Progression-Am I Crazy?

Okay, so I've got too much free time this summer. And I've been to meetups and worked on the hones of real honemeisters that were just a mess: grit and tape residue all over, and yet they get spectacular edges.

Maybe it's the OCD part of me, but lately here is what I have been doing before putting away the hones at the end of a session; in fact I did it just now:

Norton 1k: Lap a few figure 8's with the DMT8C-pretty standard. Then with a very fine older diamond hone, and maybe even a little with the 4k.
Norton 4k: Ditto the DMT/fine diamond plate, then Norton 1k and finish with a few figure 8's on a PHIG or NAni12k.
Norton 8k: DMT/fine diamond plate (and its' the combo stone so I can't use the 4k side on it!), then the now very smooth Norton 1k, and maybe a few laps with the Nani12 or PHIG
Nani12k: Fine diamond plate, Norton 4/8, and finish lap on the PHIG.

Believe it or not, I didn't sit down and plan this out; my hands just sort of started doing it during cleanup lapping, then noticing the glass-smooth hone surfaces it leaves behind. Honestly, I can't tell that it makes a whit of difference in my edges (though they have been getting much finer due to more razors and more practice).

I know there is a school of thought that says don't do this, as it works against the intended grit of the hone (except in the case of arkies, a rabbit hole I have yet to fall down). But what about the argument that maybe it could leave a finer scratch pattern coming off each grit stone?

I'm just curious if anyone has done a more thorough, scientific study of this. What do the honing gurus think? Thanks for any thoughts. Aaron

I know it has been recommended against here, but I have gotten to the point that I lap all my stones on 400 grit sandpaper on a flat surface. I do make sure that no residue from the sandpaper remains on each stone and have never had a problem. I do this with all my stones from 4K up including my treasured 20K Gokumyo. I have resisted the tendency to finish lapping on higher grits and figure that a 4K or 20K stone will be whatever grit it is irrespective of how the lapping is finished. While I have done no scientific experimentation with this way of lapping, my results certainly verify that it is causing no problems. I do have the 325 grit DMT as well as the 140 and 400 grit Atoma stones, but I never use them anymore for anything but occasional work on my knives.

I surface my hones on a per-stone basis. Some I like with a coarser finish and some with fine. For instance, I prefer a coarser finish on most fine hones as it helps them cut faster and gives pretty much the same finish, as well as helps get rid of the stiction and grabbiness. The exception to this is fine hones that are extremely slick. Those I might prefer to finish a bit finer to get a little better feel, depending on the surface area in contact with the stone (which depends on what I'm honing). Those stones I tend to finish both sides - one side coarse and one side fine. I recently tested all of my stones with both fine and coarse finishes while using a test workpiece to check the resultant difference in surface finish. The test piece was a sort of cone shaped piece of hardened steel with a 1/4" diameter flattened end. The coarser stones' resultant surface finishes are slightly affected by stone finish level but not a whole lot. Cutting speed is significantly affected with many stones. The finest stones seem to show no difference in resultant surface finishes but drastic difference in stiction depending on surface finish. (I.E. my Suehiro Gokumyo 20k gave a mirror finish to the test piece whether finished with a DMT XXC or lapped with a DMT C, then quickly dusted with a DMT XXF and even kissed with a Shapton 12k).

The stones I tested were Suehiro 1,500 and 20k, King 800, Shapton 2,000 8,000 and 12,000.

The only -ve I'd point out is that DMT recommend lapping with nothing finer than their DMT C. The finer DMT's will lose their diamonds quickly with a lot of lappping.

As for the rest you are simply making the stones flat so doesn't really matter how you do it tho the pavement should be reserved for extreme cases .

I'm going to say that yes, you are crazy.

I have found that hard stones will show scratches from lapping, and I will finish those off at a higher grit. But those don't need to be lapped often in the first place.

Very hard stones will have more of a tendency to stutter with very fine lapping. I also wonder how much of my hones life I am wasting with a lot of lapping, although I am really just giving them a quick couple of figure 8's to clean them. Hopefully they still get a lot of use. I can see they are thinner but none of them are new stones by any stretch of the imagination, so I guess I'm really saying it is likely shorter but they still last a long time. Funny how things make more sense and I answer myself as I type

Originally Posted by RezDog

Very hard stones will have more of a tendency to stutter with very fine lapping.

Mine don't. I think it might depend on some other factors,maybe the type of stone.

Originally Posted by RezDog

Funny how things make more sense and I answer myself as I type

I have past that age.... I now forget the question that I thought I figured out! But that's OK, I'll remember later. Usually much later.
I tend to over flatten mine. Yea I know, sounds wrong.

I have pretty much followed the school of Glen. Something I noticed in his style of teaching is that what ever works for you is the best way. I take that to mean what ever gives you the most confidence in what your doing which in turn will get you to be where you need to be. He shows you what and how he does things as a basic starting point and it's up to you decide from there. Do I do everything excactly like he does ? NO, I flip my razors the proper direction :<0)

If it works for you, your doing it right !

This is one of those questions that has a great many variables to answer. Among the elements already raised should be added type of steel being sharpened, sharpening procedure/protocol, type of stone being considered (bonding agent), and etc. The surface scratches from lapping may not last long enough during the honing procedure to matter or even be detectable, depending upon the stone type/construction.
I do a lot of work (daily) with both the Nani Super stones and the Choseras. These stones are very different in how they work the steel. IMO one would have to compare stones of the same type and to approach an accurate conclusion would require a specific laboratory and disciplined conditions.