Gallery, Projects and General > How do I??

Is it possible to make a poor man's flat stones with a glass plate?

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Pete.:
'Flat' just means that enough evenly distributed points create an average plane. That wavy surface on the 1-2-3 block - that was still flat as far as it's function as a 1-2-3 block requires. Just 'seeing' waves in the surface doesn't mean it has been poorly ground, you can take a normal hand scraper and put any pattern in a surface that you can see without affecting the dimension to any degree that you could measure.

JHovel:
I may not have communicated accurately enough, so here are a couple of doctored microscope images to illustrate what I believe Robin Renzetti proposed and achieved - and I copied, seemingly successfully:

sparky961:

--- Quote from: JHovel on April 01, 2018, 08:32:30 AM ---here are a couple of doctored microscope images

--- End quote ---

Not to be purposely argumentative, but I'd like to see actual unaltered images showing the same thing.  I don't think what you've illustrated is possible.  The abrasive grains will either be ripped from their bonding matrix and/or fractured in a somewhat random fashion depending on the material and orientation.

Of course, this entire discussion is hypothetical.  The original question, as I interpreted it was "is this a waste of my time"?, to which I emphatically say "no" until proven otherwise.  If it's proven otherwise by doing the experiment then it wasn't a waste of time, now was it?

JHovel:
Well, sparky, sadly I don't have the means to do microphotographs....
The reason we use fine-grit diamond surface grinder wheels for this job is that they don't rip the aluminium oxide grain out or fracture them, but abrade them flat.
All I can tell you that my stones no longer work to sharpen anything, just slide across smooth surfaces. They will, however, make any tiny burrs shiny, so I can see where they are. By concentrating pressure a little on the shiny spots, they soon disappear and the stones slide again.
Since that is the intention of flat toolmakers' stones, I'm happy with the result.

vtsteam:
Sigh, still no actual results.

Okay seems people don't really "get" the three stone method, and confuse it with "lapping" and confuse lapping with sticking sandpaper on some reference flat.

Three stones theory works like this. Rub with short circular strokes two reasonably flat same grit surfaces together enough, they become negative images of each other. One has humps where the other has matching hollows.

Then take a third, again same grit surface, stone and rub it against one of the earlier pair -- ideally and theoretically,  it now wears into a negative pattern of the second stone, and a matching pattern with the first stone.

Then rub those two together and again theoretically and ideally the matching high spots now remove each other to achieve a greater flatness than either had to begin with.

Theory and idealism depart if you realize the third stone actually imparts some new contours to the second stone. But by repeating the round robin process, all three stones gradually remove their combined differences and flatness is achieved.

That's the theory.

Whether this would work in the scenario first proposed, I again don't know the answer to, nor does anyone else who hasn't actually tried it.

Which is why it would be nice if the proposer actually did that and reported back.

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