Re: [CAD_CAM_EDM_DRO] Home built machine setup, perpendicularity

David A. Frantz wrote:

>Is there an online reference to generating squares? Much to be found
>with respect to falt surfaces and scrapping, someof which I've done
>years ago, but i never learned how to generate a square.
>
>

I just did this a few months ago. I bought a "hand scraped square" on eBay.
it was a nice casting, but the "scraping" looked like somebody had hacked on
it with a dull axe! (Not that I was really expecting a precision
finished tool,
I was happy to get a good casting to work on.)

So, I bought an 8" angle plate on eBay and cut it in half, making two 4"
x 8"
x 8" squares. Now, I had 3 squares to work against each other. I finished
the long side of the master square and one face of each small square on
my surface plate. Then, I marked the master square "A", and the other two
"B" and "C". Then, I started by inking C and wiping it against A, and
scraping
the face of A. After a bit, I cleaned and inked A, and wiped it on B,
then I scraped B a bit. Then, I cleaned and inked B, printed it onto C, and
scraped C. I repeated this rotation, doing 2 or 3 scraping cycles on each
piece before moving on to the next piece. When it got close, I then did
only
one print and scrape cycle on each piece before moving to the next.

Oh, to be clear, all the time, the first finished surface of each piece
was left
facing down on the surface plate, and the printing and scraping was all done
on the 2nd face of each angle. The first face can be made flat with
only the
surface plate, but you need the 3 pieces together to make a square.

This all took about 2 weekends.

Jon