Thread: Coticule destroying Mini DMT?

Alright, I need some insight/feedback from folks experienced with using a Mini DMT to raise a slurry...

Thinking I could use it to raise a slurry on a variety of stones (versus needing a piece of coticule to raise a coticule slurry... a piece of thüringian to raise slurry on a thüringian... ect.), I recently picked up an extra fine grit (1200) mini DMT.

Using light pressure, I ran the shaft of an old screwdriver across it several times to knock off any loose pieces of 'diamond'. Then took it for a test run on a coticule...

It produced a dark gray slurry - an obvious sign that the coticule was breaking down metal off the DMT.

Repeated the screwdriver shaft exercise a few more times to make sure it was loose diamond/material coming off the DMT; then tried to raise slurry on the coticule again...

Same result - dark gray slurry:



Inspection of the DMT shows 'polished' sections on the majority its surface. Mind you, this is after just 4 brief slurry tests...



On the other hand, when I use my large 1200 Ultra-Diamond plate, it creates good ol' regular cream-colored slurry...



This leaves me with two questions:

1. Are the DMT minis simply (e.g. known to be) this much less durable than normal DMT plates?
2. Or did I get a 'bad' one?

Any thoughts or insight from others with Mini DMTs would be much appreciated.

I do not have a mini DMT, just a large DMT plate. My guess is that you have a defective one.

If you go to Dia-Sharp's website (they make the DMT) and look at their FAQ you'll find that they don't recommend any plate over 325 for lapping waterstones, and the 325 under running water. Normal for a stone to strip the diamond off of a 1200 DMT. I've heard that the Atoma are made differently and you can lap with their 1200 but I don't know firsthand.

Just from the pictures, I think something is wrong.

I would like you to test the mini a bit. Get several pieces of glass that have no scratches and rub one on each section of the mini, new looking, slightly worn, and polished. The results should be educational. I have some of harbor freights cheap perforated diamond hones. They are not perfectly flat and show wear spots that still cut.

Jonathan

Thanks for the info Jimmy. I wish I had visited the Dia-Sharp FAQ before picking up the MiniDMT from another vendor (via the bay). Fortunately I'm only out about $14. After checking out the FAQ, I also see that Dia-Sharp makes a plate specifically for lapping waterstones - but I'm not ready to dish out $200 for the ability to merely raise a slurry...

This whole quest for a 'universal' slurry 'stone' was started due to my purchase of a Zulu Gray hone sans slurry stone. I already have slurry stones for all my other stones. So, maybe I'll just drop $6 on some wire saw blades and cut a corner off it to use as a slurry stone... or inquire with Michael about purchase a small chunk for use raising slurry.

Jonathan, that would make an interesting experiment. The next time we're tossing out a glass jar or bottle I can break, or am buy some place that has glass shards, I'll grab a few and give it a go and post back with results.

I have a credit card sized 325 DMT plate that cost me about 5 to 7 bucks (can't remember) and so far so good. That $200 plate may be good but I'm with you on that. Too much of a good thing IMHO.

Originally Posted by JimmyHAD

I have a credit card sized 325 DMT plate that cost me about 5 to 7 bucks (can't remember) and so far so good. That $200 plate may be good but I'm with you on that. Too much of a good thing IMHO.

Jimmy, does the 325 score the surface of the hone much... or does it leave it pretty smooth and scratch free?

Looks like the diamond hones they sell at harbor freight. They def get the job done but are NOT perfectly flat.

I have a credit card size 325 too and it does the same thing, metal and diamonds come off all over the hone. On my Nakayama it's impossible to use as the Nakayama is so hard that the slurry is all metal and diamonds.

I stopped using the card.