Thread: Some tips about DMT

Some time ago a friend of mine asked me to repair his log splitting axe. He had lent it to his FIL, who thought that splitting logs can be done on cobbles

Anyway since it is shaped like a giant quarterhollow, I decided to try and make it as sharp as possible. The steel is very hard (can't really file it) and I had to use my DMT to repair the bevels and take out the nicks. Here are a couple of things I observed

1) I honed back and forth like if I had to set a bevel on a big wedge. I really put my shoulders into it and the DMT took this without a problem. after a LOT of grinding, it still lapped hones without a problem. There was no discernable loss of cutting strength.

2) Even though I celaned it afterwards, there was a lot of swarf loged between the diamonds. I couldn't really see it, but I noticed that my norton 4K became darker with lapping instead of lighter.
I solved this by taking a cheap synthetic hone, and scraping the DMT surface clean. I held it to the DMT like I would hold a paint scraper, and again put my shoulders into it. The surface became cleaner after awhile, and the surface is still sparkly. I removed a good deal of material from the cheap stone.

3) I tried honing that axe on the back of my norton flattening stone. Problem is that the norton 220 material is so soft as to be nearly useless. It dished out so fast that imo a norton 220 is as much use to honing as a sponge. when I gave up on it, it had dished out more than 1/8 in the middle, and I thought lapping it on my DMT would make it flat again. BIG MISTAKE. Because the stone was so dished out, it scraped against the short ends of my DMT. A DMT does not have diamonds on the side, so the stone started eating into the honing surface of the DMT from the side.
The corners of my DMT now have small bald patches where the nickel and the diamonds are gone.
lesson learned: do NOT lap severly dished out stones on a DMT. flatten them on coarse sandpaper or concrete first, and then finish on the DMT.

I thought these items were worth sharing. Especially since (3) is a good way to destroy a lapping plate, you might want to avoid that.

The basic lesson is to never loan an ax or splitting maul to anyone. You will always get it back with either a busted handle or a trashed edge. One or the other is a guarantee in my experience!

Bruno, I think your problem when trying to flatten the 220 grit hone was the fact that it's as coarse or coarser than the DMT you were using. There are warnings about this in the Shapton literature where their GDLP is not to be used on hones coarser the 500 grit. I'm assuming your DMT is either the usual 320 grit or perhaps the coarser 220 grit but in both those cases the diamond grit is either smaller or the same size as the grit released from your 220 grit hone you are trying to flatten. It stands to reason that such a coarse grit hone will dig into the Chrome plating that holds the base of the diamonds on the DMT in place and thus create excessive wear on it, ie. the DMT.

Regards

Christian

Yes... i too learned the hard way, the Norton 220 grit is useless for anything but a razor. I lost 99% of the 220 side of my combo hone thinking i could hone a couple of kitchen meat cleavers with it... it dished out... then after I flatten the stone, half the material went down the drain... the rest was gone after i sharpened another knife... just too soft.
Now i have a perfectly good 1K with a slither of 220 grits...

I don't think you can find a extra coarse synthetic stone that does not disappear like that. Diamond plates are simply superior to all others in this regard.

I believe if you rub the stone perpendicular(short dimension parallel) to the lapping plate on the high ends one could avoid plate damage. But of course such a situation is perfect for a concrete paver or block.

The other aspect is to utilize the entire surface of the stone in as equal a manner as possible

How you rub a 220 grit water stone on a 320 grit diamond plate hone will not matter. The larger 220 grit will reach the base of the 320 grit diamonds and abrade away the Chrome plating that holds the diamonds in place before the 220 grit is knocked loose. I'ts a simple "Mines bigger than Yours!" issue. The only way to flatten a 220 grit hone with a diamond hone without damage to the diamond hone is to use a coarser diamond hone such as a 120 grit or even coarser. Better yet as mentioned above, use a glass plate and wet/dry paper to do the job. Best way is to simply use the 320 grit diamond plate for honing and chuck that 220 water stone in the drawer where it belongs.

The primary reason for loose bind of the grit in such coarse water stones is that you want the grit to release as soon as it begins to dull... after all, you're trying to hog off metal fast and dull abrasives simply slow the process. The idea is that as soon as you have established the approximate shape you would move along to a finer grit and start to refine the shape so the rapid deformation of the coarsest hones is considered a necessary evil that can be lived with.

Christian

Originally Posted by kaptain_zero

you're trying to hog off metal fast and dull abrasives simply slow the process. The idea is that as soon as you have established the approximate shape you would move along to a finer grit and start to refine the shape so the rapid deformation of the coarsest hones is considered a necessary evil that can be lived with.

Christian

But the quick dishing also means that the bevels becom severely rounded.
Going to the next step (starting with a flat hone) means you have to hone away an awful lot of metal before the new hone touches the edge again.

The norton 1000 dishes as well, but it is manageable.
The norton 220 falls apart nearly by looking at it. It is really a worthless piece of hone. It deforms so rapidly that you have to spend a lot of time with the 1000 just to get back to honing the edge.

I hope this does not sound like "Norton bashing" but it's true...
The N220 reminds me of "chalk"... it starts to crumble before you can remove enough material from the steel.. I use the word "crumble" because that's exactly what happens. Then you have to flatten it again... and this is where you lose most of the material from the hone.
I have seen grinding wheels go through a hell-of-a-lot more steel before dressing.

We need to remind ourselves from time to time that Norton hones, Shapton hones and pretty much all modern man made hones were NOT designed for razor sharpening. They are meant for tool sharpening and as such intended to be used in a proper fashion. If your hone (remember, we're now sharpening oh.... lets say a chisel, held in a sharpening jig) begins to dish it is because you are not using the surface evenly. Dishing in the center means use the ends more. Of course, the uniqueness of the straight razor and the way it's sharpened pretty much makes this impossible which brings us to the inevitable dishing. This does not mean the chalk like Norton is useless, only that when used for razor sharpening, it is probably not a good choice. As for having to do a whole bunch of extra work on a 1k or 2k hone after initial work on a 220 I agree, there will be some additional work required if the 220 stone dished severely but if it was dishing that bad, the operator should have stopped and flattened the 220 hone before continuing. Those who work in machine shops and who have to shape and sharpen high speed steel cutting tools can tell you they often have to stop in the middle of shaping a tool to redress the quite soft grinding wheel which has to be that way or it would simply burn the steel as the grit dulls. But... we've already solved this problem for razors.... simply use the DMT instead and don't worry about it!

Regards

Christian

Originally Posted by kaptain_zero

(snip)This does not mean the chalk like Norton is useless, only that when used for razor sharpening, it is probably not a good choice. As for having to do a whole bunch of extra work on a 1k or 2k hone after initial work on a 220 I agree, there will be some additional work required if the 220 stone dished severely but if it was dishing that bad, the operator should have stopped and flattened the 220 hone before continuing. Those who work in machine shops and who have to shape and sharpen high speed steel cutting tools can tell you they often have to stop in the middle of shaping a tool to redress the quite soft grinding wheel which has to be that way or it would simply burn the steel as the grit dulls. But... we've already solved this problem for razors.... simply use the DMT instead and don't worry about it!

Regards

Christian

I am relatively new at this but I have jumped in with both feet and have the 325 and 1200 DMTs. I like the 325 for lapping some stones and occasionally removing larger chips. I bought the 1200 for setting bevels but I don't care for it as I find it tends to leave micro chips. Perhaps it is my technique ?

I have come to prefer the Shapton 1k and 2K pro for setting bevels, removing chips followed by the natural coticule. First the blue then the yellow. Finer hones for finishing sometimes the Escher blue/grey sometimes the Shapton Pro 15k and 30k.

I have had really good results with the Norton 4k and 8k 8"X 1 1/2" for smiling blades or warped spines. No problems with dishing and they get the razor shaving sharp. So I guess even with hones and honing YMMV applies.