Worn out diamond stone?

[Brian Kincaid]

So I spent some time on Saturday cleaning up my great grandfather's no5 (pictureless heritage gloat). Using my medium (400) diamond stone to flatten the back of the plane blade I realized I was working really hard and not getting anywhere. I inspected the stone and it looked fine, same as always, except that there was no slurry. It looked like the stone had just completely given up cutting.

My understanding was that diamonds are forever so I am quite confused about this. The stone was a Rockler Diamond stone 81604, I've had it less than a year. I thought it was a quality stone? I have sent a support request to Rockler to see what they think.

So, questions:
1) Are diamonds forever? I thought that was the consensus, and that's why I bought it.
2) I tried cleaning with water and a towel, furiously scrubbing. The stone looks very clean. Any suggestions?
3) Since I'm quite hard headed, I just kept working on it and soon the high spots of the plane blade started getting more polished (better finish than my 1200 superfine diamond stone leaves). Could I have somehow transformed my 400 medium stone into a 2000 ultrafine diamond stone? This seems crazy.

Anyway, thanks for listening... :D

Brian

[Jamie Buxton]

I too thought that diamonds were forever. However, I had one diamond stone which seemed to have worn out. I don't know what I did to it to make it that way. I've replaced it (I now have three of various grits), and the replacements seem to be doing just fine.

[David Keller NC]

"Could I have somehow transformed my 400 medium stone into a 2000 ultrafine diamond stone? This seems crazy."

Diamonds are only forever in James Bond movies. ;) What you're experiencing is normal with diamond stones. Initially, the surface is quite coarse, and during use, the diamonds fracture and get pulled from the nickel alloy substrate, leaving behind a finer surface.

One has to remember that while diamonds are the hardest natural substance known, and so will abrade anything, they are also brittle, so they will fracture in use.

Were it not for this property, a diamond as a piece of jewelry would be very, very expensive - many times what they sell for in a store, because bigger diamonds are fractured into smaller pieces, and these smaller pieces are then cut (actually, abraded) and polished into gemstones. If they didn't fracture, a bigger diamond would yield only one jewelry stone.

This is, by the way, one argument for synthetic waterstones and oilstones over diamond stones for sharpening steel. The diamond stone has the advantage of never needing flattening, but because the layer of diamonds is just at the surface, it's not going to last as long as thicker waterstone or oilstone where the original surface coarseness can be renewed by removing the top layer.

By the way - it's probably worth scrubbing your diamond plate with scouring compound (i.e., "Comet") and water to see if you can remove any built-up iron particles and sludge. That's the recommended procedure for DMT stones.

[Mike Henderson]

I agree with David - nothing is forever*. There are two different kinds of diamonds - and one kind lasts longer than the other (and is probably more expensive).

I use the DMT plates and find them very worth while. I use them for flattening the back of a plane iron or chisel, and for flattening my waterstones. I figured I'd get a year out of them, but I've had the diamond plates for couple of years now and they still work okay, but not a fast as they did when new. One of the major advantages of the diamond plates for flattening a water stone is that the diamond plate is flat.

Mike

*William Saroyan quipped, "Everybody's got to die, but I always believed an exception would be made in my case." Diamond stones are the same.]

[Joel Goodman]

I believe that the DMT uses the more expensive "mono-crystal" type which is supposed to last longer. I have also had good results with the DMTs.

[Mark McGee]

I thought I had worn out my DMT diamond stone, so I sent it back to DMT. They cleaned it and sent it back to me with a cleaning kit. What you need to do is scrub it hard with an abrasive powder and a scrub brush. And they did say it is alright to use it to flatten waterstones.

[philip marcou]

So I spent some time on Saturday cleaning up my great grandfather's no5 (pictureless heritage gloat). Using my medium (400) diamond stone to flatten the back of the plane blade I realized I was working really hard and not getting anywhere. I inspected the stone and it looked fine, same as always, except that there was no slurry. It looked like the stone had just completely given up cutting.

My understanding was that diamonds are forever so I am quite confused about this. The stone was a Rockler Diamond stone 81604, I've had it less than a year. I thought it was a quality stone? I have sent a support request to Rockler to see what they think.

So, questions:
1) Are diamonds forever? I thought that was the consensus, and that's why I bought it.
2) I tried cleaning with water and a towel, furiously scrubbing. The stone looks very clean. Any suggestions?
3) Since I'm quite hard headed, I just kept working on it and soon the high spots of the plane blade started getting more polished (better finish than my 1200 superfine diamond stone leaves). Could I have somehow transformed my 400 medium stone into a 2000 ultrafine diamond stone? This seems crazy.

Anyway, thanks for listening... :D

Brian

There are diamond stones and diamond stones. Those $8 plate sets are not the same as say a DMT type. The "stone"is only as good as the "" diamonds" adhering to it- no diamonds no workee.....Cheapee stone doesn't hold its diamonds.....And mono crystalline diamonds are superior to polycrystalline, hence the price range of these things.
Try using that stone with kerosene and see if it makes any difference.