Thread: Lapping Plates

I guess it depends on how you hone how important having a honing stone that is lapped dead nuts flat is. For me close is good enough and the old DMT 325 works just fine.

Bob

Yea, if you have a lot of lapping to do on a hard stone, 60 grit Silicon Carbide on a steel cookie sheet, will dramatically cut your time. And cost but a few bucks. You can go up to 500 with loose grit. Once flat, the other grits go fast.

For synthetics, get a 140-grit plate, CKTG has a great one for 40 bucks that will take a beating and is great for lapping stones. Then smooth with finer plates.

For hogging off material the CNTG, DMT or Easy Lap plates work well on synthetics, most do not need a super smooth finish and you can smooth them easily with another stone or synthetic nagura. A small Translucent or Black ark works well for this and for removing swarf.

For naturals garden variety Diamond plates, also work well, but for finishing hard naturals, like Jnats, Atoma’s work best for pre-finishing or spend some time smoothing with a hard tomo.

On hard finishers, once you think you are done, take your beater/test razor (one with a straight edge, not smiling) and without tape on the spine, wet the stone and do a couple slow laps. Feel and listen for a rough spot or change of sound. If you hear or feel one, that is a rough or low spot. Try to locate the exact spot by alternating directions to locate the spot, mark the side of the stone with pencil for locating later.

Then lap some more, using a pencil grit until it comes off completely, in one or 2 strokes. If you leave a low or rough spot, it can drive you crazy trying to get a finish edge, because as the stone wears the rough spot will come up, and scratch instead of polish. You can also do the same with a tomo, going slow, polishing, feeling and listening.

Know of anyone else selling the 140 plate? I'd be willing to try it. On second thought maybe not, it says in the description for the 140 that if you need accuracy buy the Atoma or DMT.
The $34.95 CKTG 400/1000 combo plate I bought from them is anything but flat, not close to an Atoma or DMT. Mine was warped and the diamonds just swept right off. Not good for lapping IME.

I think I'll stick with the powders...

Originally Posted by mainaman

I lap under running water and do circles and x pattern to make sure particles do not get concentrated in the middle of the stone. Works well for me

I've tried that, but can't seem to shake the thought that I'm 'wasting water.' Particularly if I'm lapping some sort of new and very hard natural stone that will take a while. Not like I live in a desert or some place where that's a legitimate concern. But it's programmed in there. I can't shake it. Works fine for quick maintenance lapping though.

What I do instead is fill the sink with enough water to dunk the hone and dip it in every so often to wash the particulate away and keep a suitable amount of water between hone and lapping plate. Or just set the plate in the bottom of the sink and swish the stone around on top of it. And of course the stone and lapping plate get rotated every now and then to keep things as even as I can get them.

I've had a bit of a lapping nightmare today, all told..

I realised that my Nakayama needed lapping. I covered it in pencil and used the Shapton plate. It took a long time and some effort.

Normally I go to the Atoma 1200 after the Shapton but this time I went straight to a soft Tomo, having recently lost confidence in those type of plates.

Honing away when I realised some thing was not rite .
I did some testing and found that there was a foreign object stuck in one part of the Jnat.

I couldn't see it or feel it with my finger but the scratches in the bevel and the obvious bump in the stroke told me that a diamond was lodged in the hone .

First time ever that has happened to me. I lapped it a bit and solved the problem.

I then tried re setting the bevel but was getting chips in the edge so I decided to let it go and re visit tomorrow

Which is why you should test with a beater/test razor and lightly polish the stone face with a hard tomo or small Ark.

Polish the stone face with a hard tomo, do 1 inch at a time using light pressure, feeling for drag and listening for change in sound.

Once you narrow down the suspect site, examine with a 20X loupe or glass.

Chipping can be caused by many things, and may not be the stone. Try another razor and eliminate the razor as the source, if you do not see a problem area, before lapping off a lot of stone.

The chipping was just because it was Hart and I was not taking due care and attention. That's why I knew it was best to leave it alone until today.
Plus those diamond scratches may have contributed?

I just set the bevel chip free, ready to rock n roll on the Jnat.

I don't like to use hard Tomo's on the jnat because they can some times scratch the stone. I prefer to take a dmt card to the tomo and get the slurry that way, granted im missing some particles from the base stone.
I always burnish with a soft tomo and it works out well for me , until just now , look what happened . haha you've gotto laugh

The idea is to test the stone face for smoothness.

By lightly running an un-tapped razor on the stone you will feel and hear any imperfections on the surface, before you put the good razor on it.

Additionally, by lightly rubbing a hard tomo on the surface on the stone you can also feel the stone face and feel and hear any defects on the stone that you may not using a razor, because you are very lightly, polishing/burnishing the stone face.

The goal at this point is not to burnish the stone face, but to feel the face for smoothness and imperfections. You only have to do this once after lapping, once flat and smooth, light lapping and slurry raising will only smooth the face further.

With naturals and slurry, you have to learn to use the slurry best for an especially hard, problematic razor. How much, thickness and how a slurry is raise, in addition to technique, pressure and the razor steel all play a part, but the slurry can play a large part.

Alex Gilmore, has an interesting post on this, in a recent blog post, on his website, here. TheJapanBlade, Why Develop a False Edge and Example of Development of a Razor Edge?

That makes sense.
It never occurred to me to check the face for imperfections.
Although I never had any issues before..

After I broke one of my soft ones I tried a hard one.. Instantly felt a rough spot. It's at the top where the blade doesn't go so no biggie but still, that is a good idea after lapping..
Cheers

Originally Posted by Marshal

I've tried that, but can't seem to shake the thought that I'm 'wasting water.' Particularly if I'm lapping some sort of new and very hard natural stone that will take a while. Not like I live in a desert or some place where that's a legitimate concern. But it's programmed in there. I can't shake it. Works fine for quick maintenance lapping though.

What I do instead is fill the sink with enough water to dunk the hone and dip it in every so often to wash the particulate away and keep a suitable amount of water between hone and lapping plate. Or just set the plate in the bottom of the sink and swish the stone around on top of it. And of course the stone and lapping plate get rotated every now and then to keep things as even as I can get them.

I prefer slowly running water but I collect the water in a plastic dishpan. I then pour that water, with the slurry, into other containers and let most of the water evaporate. The concentrated slurry is then used on hones.

If you don't want to waste the water, you could dump it onto outside plants or use it to fill your toilet tank.