Re: State of the art?


Bill Thomas <bthomas32000@...>
 

from what i have experienced, polishing requires the greatest amount force - my 24" machine http://www.yubagold.com/mom/index.html
uses 1/2 hp and 1/4 hp - two stock M-o-M systems - using ball bearings - more than enough power.  i should replace the M-o-M system with 2 monster variable speed control motors which a friend gave me - would eliminate the belt hassle changing.  the other change i need to make is moving the arm pivot back further from the table axis so as to increase the radius of  the "quill" arc -  also on the website pictures the "arm" is counter balanced like the old high end LP record player - so as to control the downward force on the lap - which i have found necessary to stop chattering of smaller laps (noticed this in a picture of a Zambuto machine).

(need to send along a picture - worth a thousand of the following words) also to that end found i needed to get the pivot (toggle pad) attachment as low as possible to the back of the tool/lap - use a 5/8" short threaded stud into the back of the aluminum plate of the tool/lap.  the toggle pad 5/8 NC female is then threaded on that stud.  the 1" top of the toggle pad then fits into a machined adapter which on the other end is then threaded on to the 5/8" NC arms quill.

attached is a "strokeSetup.pdf" which i use to setup my modified M-o-M and record the settings.  also attached is a spreadsheet i use with my homemade sphereometer - the radius of the 3 legs from the center of the dial indicator was done with a bar of approximate 3" radius - then the actual radius was determined by measuring a mirror of known focal length (using excel solver).  it is vary accurate.

but i don't think a M-o-M type machine will be what you need for a closed loop system - would be more like a Zeiss machine?  also think you will need to know the exact RPM of the table and arm to avoid repatriation of strokes  - one crude method is to mark on the edge of the mirror where the tool/lap crosses the edge - those dots should be uniformly spread out.  stroboscope would be better?

On 11/15/2019 3:11 AM, Rien wrote:
Again, I have to thank you Bill. To me this is like opening another door of which I did not even know it existed.
I will study both the site (yubagold) and the pdf. I am however not yet in a knowledge state that would allow me to make sensible comments on it.

Btw, I have pretty much decided to make the CNC machine -that I was planning anythow- sturdy enough to also handle grinding/polishing forces. That does not impact my schedule too much and at least gives me the option to start experimenting with CNC grinding/polishing whenever I feel ready.

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