Lapping a Gokumyo 20000?

Sup fellas,

Chances are, in some point in the future, I'll be getting a G20. I've done a bit of searching and haven't found the info I'm looking for.

I've been lapping my small variety of stones with the following method:

Pencil grid all over the hone surface.
Over a 400 grit wet/dry sandpaper over a 14"X14" piece of marble, in the sink or tub, begin figure 8 patterns, alternating with circles, flipping the stones orientation around intermitently.
I repeat this step until the pencil grid lines are completely gone and then re-grid and lap til gone again. I also chamfer the edges gently.

So, is this process sufficient to properly lap a G20, in the even that one arrives?

Regards,
Simon

Sounds good to me though I've always used diamond plates. Usually 325 grit but lately going to the Atoma 1200. I lapped the non lablel (ink stamped) side of my 20k though some guys do them both or just the label side.

Yeah. Saw the whole thread on that. It nearly got down to someone having to develop a technical reason for lapping this way or that. LOL. Love SRP.

Thanks, Jimmy.

It'll work.

I normally take finishers up to 1000g, but you don't have to. IIRC, The 20k is extremely hard, and may take a while. Like Jimmy, I use DMT's. If it's a very hard stone, I'll start with the DMT XX, go to the DMT C and finish with the Atoma 1200.

If your using wet dry, I would use 60 grit to start. The 60 gets it flat and the other grits will take the 60 scratches out. Ex 60, 100, 180, 400, 600 and 1200. The 60 really speeds it up. Jut wash it all off well and you will be fine.

If you have an Arkansas hone that's a good size you could try that. I use an arkie to lap my Naniwa superstones. I also found out that Niel Miller uses an arkie in a similar way.

I would not want to touch it with anything that sheds grit. It's just too risky to think you could push some low grit into the face that you then have to lap out. So that rules out all loose grit, and paper bound grit systems.

The other options would be high grit DTM's 1200+ Or lapping film.

I did both sides of mine with 400 grit wet/dry sandpaper, continue to do so after using it and have had no problems.

Stuart from Tools from Japan suggests the diamond plate and discourages you from using paper......my SG needed very little lapping on a 325.

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Originally Posted by bill3152

If your using wet dry, I would use 60 grit to start. The 60 gets it flat and the other grits will take the 60 scratches out. Ex 60, 100, 180, 400, 600 and 1200. The 60 really speeds it up. Jut wash it all off well and you will be fine.

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I have done what Bill says had no problems ..or you can use the method ur doing then take that 1000/3000 grit stone they give you and hit the 20 k with that.. By the way that 20 k is a great stone good luck!!

Regardless of what you lap your stone on, a semi wornout DMT 325 will put a nice smooth surface on any of your finish stones after lapping.

I only did one side of mine tho I started out doing both. My stone was warped so it was easier to get it flat on the concave side ie the side that had contact at the 2 ends rather than only in the middle which tends to rock & promote the same shape..
Finishing off with a coticule or nagura gives a nice surface.

As far as any hone that seems warped to one degree or another, I was in the refractory business for 15 years and I can tell you the any ceramic that is fired in a kiln is subject to any temperature variance during the firing process. Therefore, some stones will need extra flattening time as a new stone. Be patient and lap your stones as often and as long as they seem to need it.

Any subsequent lapping will take less time than the initial lapping. I believe that Lynn posted that he has lapped as much as 1/8 inch or more from his Norton 4k stones before they worked well for him. Man made could mean made last week. Natural usually means made 50,00 years ago or more. Have patience with your stones. Give them a second chance to work for you.

I'm just saying.....:gaah:

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Originally Posted by WW243

Stuart from Tools from Japan suggests the diamond plate and discourages you from using paper......my SG needed very little lapping on a 325.

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Interesting. Can you expound a little more as the reasoning? I'm soakin' it all up and takin' with a grain of salt, baby!
:popcorn:

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Originally Posted by Siguy

Interesting. Can you expound a little more as the reasoning? I'm soakin' it all up and takin' with a grain of salt, baby!
:popcorn:

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The nickel bonding the diamonds to a plate is stronger than the glue holding abrasives to sandpaper so embedding grit is less likely with a DMT etc. Also flatness is more precise as paper does have some give.

With that said it's hard to imagine any particles embedding in such a hard stone as the G20k