Precision Ground Flat Stones

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ctwo
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Location: Silly Cone Valley

Precision Ground Flat Stones

Post by ctwo »

I seen it on yootoob. I bought a couple stones off ebay thinking I'd make me a pair. I was going to hold them with parallel clamps on the mag vise. Naturally I'm always concerned about these grinding wheel exploding, so does this sound safe enough?

What I do not understand is that they've been told to rub the stones together before/after each use to keep them flat, but doesn't that result in a convex and a concave surface?

Now, the stones I received feel like soft limestone, so I guess they useless for this porpoise?

Please advise. Thanks
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
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jcfx
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Re: Precision Ground Flat Stones

Post by jcfx »

I bought pre ground tool room stones off eBay, they came in the original Norton OEM boxes and they're marked as sharpening stones
one side is gray the other brown. The Norton stock number ( ? not sure ) is - NTIB134
they defintely aren't soft.

I don't think rubbing two super flat surfaces together would result in dipping of the surfaces.
My understanding is rubbing of the stones together face to face is to shear off any particles that may be proud of
the precision ground surface, this site has a good explanation - https://www.kineticprecision.com/all-about-pfg-stones1
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ctwo
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Re: Precision Ground Flat Stones

Post by ctwo »

Thanks! I checked out the website. Oddly, I have to have a youtube account to watch their video. I lost my account a while back and haven't felt like playing ball again.
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
Mr Ron
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Re: Precision Ground Flat Stones

Post by Mr Ron »

Harold; I have never heard of PFG stones before. Have you ever used them? Their description makes sense for maintaining flat surfaces. At $200 a pair, what do you think?
Mr.Ron from South Mississippi
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Harold_V
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Re: Precision Ground Flat Stones

Post by Harold_V »

I'm not familiar with that particular product, although, in theory, they may function as represented. Seems like a lot of money for something that one may rarely have need for, if ever. If one uses them for typical stoning needs, they are most likely not to retain their flatness for long.

I own a set of Starrett (Webber) gauge blocks, which came with a hard Arkansas stone intended to be used for ensuring that blocks are burr free and will wring properly. It stands to reason that one would use such a stone sparingly, if at all.

H
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jcfx
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Re: Precision Ground Flat Stones

Post by jcfx »

Having used them for a little over 3 years now I find them very useful in maintaining flat surfaces,
since they only work on projections off the surface, doesn't make a mark on the flat surface.

A machinist square I have would never be square ( just off half a hairs width ) I thought the beam somehow got bent
since it took many a dive off of improvised work surfaces over the years, when I got the stones I figured it cant hurt, turned out there
was raised bump where the base hit the floor and it's square after stoning.

There is a seller on eBay that sells precision ground toolroom stones, for a little less than what kinetic precision does.
Carrdo
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Re: Precision Ground Flat Stones

Post by Carrdo »

I have a pair of precision ground flat stones (Norton based) and use them to stone my milling machine table, the base of my milling machine vise and top/bottom of the rotary table, the top of the surface grinder magnetic chuck and any other precision flat surface periodically after use.

If people like Robrenz, Steve Barton (Solid Rock Machine Shop) and Lance Baltzley use and highly recommend their use then....
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