Thread: Precision ground toolroom stones

Originally Posted by Pete F

Yes it needs to be a diamond wheel. No you can't lap them. Robin specifically made that point in the video.

Flatness is only part of the objective. The diamond wheel actually cuts the abrasive particles in the stone and leaves them with flat tops, that's how these stones function. That's why I said they feel "interesting" to use. Not like a normal stone at all, regardless of how flat the stone is. They feel very different to the touch, quite smooth. Ant sharp protrusions get forced below that top plane and sheared off by the particles below. I was experimenting with them last night both with scrap stock that has been ground and them thrown in the scrap bin and also intensionally centre punching some steel I'd previously ground. Where there was a raised surface the stones took it down to the surrounding surface and then just burnished the surface.

That's very interesting, I thought the video was saying that they can't be lapped due to the inability to rotate them. He showed how they can conform to one another if you don't rotate them, but if you rotate them the illusion of flatness is removed.
If, however, you cannot lap them because they would simply 'knock stones out' of one another rather than making them flat that is something different.

Yes, Pete's report matches my findings exactly. They just 'glide' across flat surfaces and you can feel any high spots immediately. I have on occasions used non-ground bench stones to reduce the height of dings after finding them with th ground stones and then levelled the remainder to the height of the flat surface (to prevent knocking grit out of the ground stones).

Originally Posted by j3dprints

That's very interesting, I thought the video was saying that they can't be lapped due to the inability to rotate them. He showed how they can conform to one another if you don't rotate them, but if you rotate them the illusion of flatness is removed.
If, however, you cannot lap them because they would simply 'knock stones out' of one another rather than making them flat that is something different.

The stones were quite flat straight out of the box, and were marked as having been ground (or words to that effect). They weren't surface ground type flat, but pretty good. However they feel completely different to use. I can't really tell any difference between the "rough" side and the smooth side of the stone when using them. The surface feels reasonably smooth from the grinding.

where can one get those finger thingies?

You can make them, and I think that’s what Robin did. Not hard and it’s just a flexture. I’ve seen another person make a jig with a door hinge as the flexing bit. Basically a C shape, with the centre of the C filled in with the hinged piece, like an E, which is slightly proud of the C part if that makes sense. With the magnet on the centre hinged part is sucked down and that pushes against the work.

I just used toolmakers clamps. Grip the stone from both ends and the toolmakers clamps will hold on the chuck. It was very secure and I was unable to move the stone

Just a quick note: my friend Felix Mu (M&G Productions) and I had a discussion about these stones. He believes he has found a way of making them available commercially but affordably. I have no idea of prices, but he has talked to a high end tool making friend of his in China who also uses these stones. Felix has found a source for suitable stones and plans to have them precision ground in his own factory in China and then brought here.
I've just asked him for an update on progress.

Originally Posted by Pete F

I just used toolmakers clamps. Grip the stone from both ends and the toolmakers clamps will hold on the chuck. It was very secure and I was unable to move the stone

yea!....now I have an excuse to buy some

Originally Posted by jhovel

Just a quick note: my friend Felix Mu (M&G Productions) and I had a discussion about these stones. He believes he has found a way of making them available commercially but affordably. I have no idea of prices, but he has talked to a high end tool making friend of his in China who also uses these stones. Felix has found a source for suitable stones and plans to have them precision ground in his own factory in China and then brought here.
I've just asked him for an update on progress.

Hey Joe,

Any update/s available?

I think that trying to grind a stone without a "real" surface grinder would be a waste of time. While the Hercus T and C can surface grind, it's pretty much pretending. No coolant, no powerfeed..............

Bob.

I have an update on the stones Joe ground for me, they absolutely kick ass and I use them constantly, yet to find a good way to clean them though.

Originally Posted by caskwarrior

I have an update on the stones Joe ground for me, they absolutely kick ass and I use them constantly, yet to find a good way to clean them though.

Lucky you Cask.

Originally Posted by caskwarrior

I have an update on the stones Joe ground for me, they absolutely kick ass and I use them constantly, yet to find a good way to clean them though.

I believe that you should be able to wash them with water and dish detergent.
Robin Renzetti uses a cheap ultasonic cleaner.
I use mine dry and haven't had to clean them yet... They seem to self clean when I rub them together - which you do every time you use them...

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Originally Posted by jhovel

I believe that you should be able to wash them with water and dish detergent.
Robin Renzetti uses a cheap ultasonic cleaner.
I use mine dry and haven't had to clean them yet... They seem to self clean when I rub them together - which you do every time you use them...

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I thought I had posted an update, but obviously hadn't.
Felix has had a couple of samples made and gave one to me to try and evaluate.
They were nice and flat and were made with 4 different grid sizes between them.
But the binder was way too soft. So they shed grains every time you touched a burr or other raised feature. Obviously they then reverted back to being a soft and sharp sharpening stone.... Not what we want for this purpose.
Felix is in China at the moment, hands-on managing his factory. Training new staff etc. I'm in regular touch with him by WeChat (Chinese version of WhatsApp).
He will be visiting the 'stone maker' to see if they can change the binder to something more resistant to grain shedding.

He will be back in a couple of months. In the meantime, his brother is running the shop in Melbourne and online.

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Thanks for the update Joe, Cheers
Rob.