[ATM] Elgin machine turntable to stroke ratio

[William Marriott]

Hello;

Yes, two motors give you more design degrees of
freedom, especially if variable speed.

I prefer 12/1 ratio, ie, spindle at 60rpm, eccentric
at 12rpm, and it would be nice if you could slow it
down to 30 rpm, and very  nice if  you could slow the
spindle down to 1-4 rpm for hand figuring work. 

But, as mentioned, for polishing out a ground surface
just about anything would work, as long as you check
the figure often, in case something is really wrong.

Just some thoughts...

Bill Marriott




--- Christopher Dalla Piazza <dalchri at hotmail.com>
wrote:

> I'm getting ready to build an Elgin machine and have
> found an appropriate 18 
> rpm motor for the stroke rate but I'm reading that
> it is best to have the 
> turntable turn faster, 2-3x the rate of stroke.  I'm
> thinking that you'd 
> avoid edge troubles with this setup.
> 
> I can't figure out how to utilize the same motor to
> drive both the stroke 
> and the turntable without some sort of gearing or
> belt mechanism and at that 
> point, I'd rather just get two motors.
> 
> If I use the same motor to drive both, I'll end up
> the other way around, 
> about 2-3 strokes for each rotation of the
> turntable.  I'm thinking this is 
> closer to the way I'm polishing by hand right now.
> 
> So, does it really matter that much?
> 
> I'd rather have something simple unless there is a
> real benefit.
> 
> Thanks for any suggestions!
> 
>
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