# Ground Flat Stones



## ddickey (Apr 28, 2017)

I heard these mentioned on one of the you tube machining sites.
Anyone use these or have any knowlwdge of them?


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## EmilioG (Apr 28, 2017)

http://www.airbearings.com/pricelist

I don't have these stones, but would like to buy them. Very expensive at $500/pair.
You get two stones to keep them flat.  If you need to stone a table or a part, these would come in handy.
Looks like they must be used properly.


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## chips&more (Apr 28, 2017)

Don't tell anybody, but I use one of my granite surface plates when I need a big flat stone.


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## 4GSR (Apr 28, 2017)

I have a set of these die stones that I snagged off of ebone several years ago for under $20.  As for as I'm concern these stones are darn flat!  You can rub them together and they almost wring together they are so flat!  Have no clue where to buy them but can look up the Carborundum number 395BY and see if anyone sells them.  Ken


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## Ebel440 (Apr 30, 2017)

I just use a regular rectangular carburondum sharpening stone about 6x2x1 with a fine and coarse side. I use them on machine tables and they seem to be pretty flat as they are. They cut very slowly and will pretty much only cut high spots. You can feel it when the high spot is gone. If a stone gets worn more in one area I just flatten it with another stone. I'm guessing you could buy three of them and work them all together until you have three truly flat stones.


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## EmilioG (Apr 30, 2017)

Any stone will never be as good a truly ground flat stone. For precision flat surfaces, I would use nothing else, otherwise, I'll create low spots and deviations of the flat plane.
I'm referring to precision ground bases and tooling, not so much a mill table.  Gage blocks require a precision ground flat stone, e.g.


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## Ebel440 (May 1, 2017)

I'm just going to play the devils advocate here. Not trying to start a fight or anything. I would actually like to have a set of these. In no way am i trying to say cheap off the shelf stones are as good. But my thinking goes to how long would they remain flat? You can't really flatten them with only one other stone. You may be able to keep them flattish but any wear in one would be high spots on the other after a while. How long would you trust it being flat for?


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## EmilioG (May 1, 2017)

The ground flat stones I linked come in pairs so they can be used together to keep each flat.
I think these ground flat stones are used very lightly on precision flat ground surfaces to begin with, so I would think they will stay
flat for a long time if not abused.  A ground flat stone will only hit the high spots very lightly. They're not made to stone off
much material at all. I don't think they're made for a very worn, rough mill table, e.g.  Stefan has a video describing them.  They're $500/pair!


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## chips&more (May 1, 2017)

I also have a few of these Starrett gage block stones (pic). I don’t really use them as intended. I use the stones to put a high mirror like finish on small parts…Dave


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## ddickey (May 1, 2017)

EmilioG said:


> The ground flat stones I linked come in pairs so they can be used together to keep each flat.
> I think these ground flat stones are used very lightly on precision flat ground surfaces to begin with, so I would think they will stay
> flat for a long time if not abused.  A ground flat stone will only hit the high spots very lightly. They're not made to stone off
> much material at all. I don't think they're made for a very worn, rough mill table, e.g.  Stefan has a video describing them.  They're $500/pair!


Yeah you wouldn't want to use these to sharpen your utility knife. Lol


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## EmilioG (May 1, 2017)

The Starrett stones look very worn, they sell for $100 new. Great to have for stoning gage blocks when purchased new.
The SW gage block serrated stone is a good investment if you buy lightly used Starrett Webber gage blocks., or any good steel gage blocks for that matter.
I saw a listing on Ebay for a Starrett Webber gage block stone in wood case. It was not serrated. Looks like the old switcheroo. 

Someone stuck an old bench stone in a Starrett case and sold it as a Starrett Webber gage block stone!


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## madmodifier (Jul 6, 2017)

Sorry about reviving the old thread but this subject came up recently on Robin Renzetti's channel


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