Precision Ground Toolroom Stones

I have a Rockwell T&C grinder that will do surface work too. I look for abused stones that are sometimes swaybacked to the max. I use a diamond wheel (I have several) to make the surface flat again. A little water mist coolant is in order as there is some heat generated. They appear to my gunsmith eye flat as a flitter (technical term) . Even hard Arkansas stones can be saved from the sad state of abuse they have suffered.
 
I wonder what effect that the heat generated by the grinding has on the flatness of the stones; I know that with grinding steel parallels dry that it is near impossible to keep them (parallel) and straight, at least on the parallels that I made about 50 years ago of 0-1 tool steel, hardened; the heat of the cut would bow them up in the middle, even with the magnetic chuck on full power. Originally, I did not worry about exact nominal size, just parallelism; this was on a grinder 16 X 72" and not in good alignment, so I thought it might be nice to grind them to nominal size, but my B&S Micromaster does not currently have coolant and the results were not so good. I do not know how much effect that the lightening holes had and how much different a solid parallel would act but assume that it would make a difference. So, with stones ground dry, how flat is flat?
 
Dresden said:
Usually a granite rubbing block is used to detect burrs
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Chips&More (Dave)'s comment earlier in the thread and yours puzzled me until I started reading about gage block stones.

Starrett still sells stones expressly for removing burrs from gage blocks, which is simply amazing to me. See page 408 of their current catalog:

IMG_0035.PNG

The cheapest of them (for steel) appears to just be a small piece of granite that is precision ground. For ceramic or carbide they recommend their aluminum oxide stones (the larger one has serrations which apparently helps with the "feel" per Starrett). The granite stone is what has my attention, though.

I think Dave may have it exactly right. The cheapest option for a "precision ground stone" may be simply a small, cheap granite surface plate.

I'd be willing to bet that rubbing a hardened and ground part on a surface plate would burnish and identify high spots identically to what you see in Robin's video.

Anyone here ever used any of those Starrett stones?
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Rex
 
Just a flat granite block will define and burnish the high spots but it won't shear them off or improve the surface like a flattened aluminum oxide stone.
 
Rex Walters said:
The cheapest option for a "precision ground stone" may be simply a small, cheap granite surface plate.
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That could be difficult to take to the work, depending on size, shape, and location. I also agree with Jon that it would only burnish, not remove burs.
 
Rex Walters said:
Chips&More (Dave)'s comment earlier in the thread and yours puzzled me until I started reading about gage block stones.

Starrett still sells stones expressly for removing burrs from gage blocks, which is simply amazing to me. See page 408 of their current catalog:

View attachment 237871

The cheapest of them (for steel) appears to just be a small piece of granite that is precision ground. For ceramic or carbide they recommend their aluminum oxide stones (the larger one has serrations which apparently helps with the "feel" per Starrett). The granite stone is what has my attention, though.

I think Dave may have it exactly right. The cheapest option for a "precision ground stone" may be simply a small, cheap granite surface plate.

I'd be willing to bet that rubbing a hardened and ground part on a surface plate would burnish and identify high spots identically to what you see in Robin's video.

Anyone here ever used any of those Starrett stones?
--
Rex
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Yes Rex, I have been using a granite surface plate for a very long time for such purposes. I didn’t mention it earlier, sorry, but I also apply some Starrett granite cleaner as I’m doing the deburring. It really helps keep the shiners/skid marks off the surface of the stone if nothing else. The stone I use is about 9” X 12”. That kind of real estate is another big advantage over the smaller examples. I’m seeing on fleaBay that a replacement, if I bought new, would be about 50 bucks. Both the surface plate and sharpening stone are a good solution to deburr. I’m not deburring every day in my shop. It’s not a priority. But, it is a needed capability in my shop from time to time…Dave
 
Bob Korves said:
That could be difficult to take to the work, depending on size, shape, and location. I also agree with Jon that it would only burnish, not remove burs.
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Hi Bob, after a surface has been blemished it can no longer be the same. So then what? Do you remove the high spot(s)? Or do you try and push them back to where they were? When I recondition my Bridgeport mill table, I DO NOT RUN A FILE OVER ITS SURFACE. Instead, I have a large flat and heavy piece of cast iron that I slide all over the top of the table. This method burnishes the table. I dislike the thought of filing metal off. That will only change the landscape forever. If my precision whatever has a blemish and I’m concerned about it. I’m not that eager to try and remove it. I would rather burnish it. This of course depends on many factors. But I would try and burnish first…Dave
 
Once a clamp, t-nut, 1-2-3 block, part or anything falls on or scratches a softer surface, then yes it's not the same. I can't see rubbing two cast iron surfaces together until both surfaces are free of raised material from scratches or dings. Looks like you would just be asking for them to gall each other and cause more damage.:(
 
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