Re: ATM Re: Grinding Machine

[Bill Marriott <btk@pacbell.net>]

Peter D. Brooks wrote:
> 

> 
> Spindle:  Currently uses a 4 step cone pulley and other pulleys and
> a worm gear system to give me speeds from 1RPM to 5 RPM.  This may be
> too slow.
> 
> Sweep arm:  Bigest section not completed, it'll be driven by a DC
> gearmotor with a practical top speed of 30 RPM.

Peter:

In general, I think you'd like to reverse the ratios of speed
spindle/eccentric.

Running both personal work, and in production at my optical shop, I've
found its best to be able to run the spindle up to 60rpm, even faster if
one uses polishing pads, and, as recommended by Bob Pfaff (is Bob still
with us out there???) and confirmed many times by myself, run an
eccentric speed of approz 1/12 times the spindle speed. By being able to
change these ratios, as well as changing MOT and TOT,you can effect 
changes of curvature between center and edge.

However, it'd also be nice to be able to slow the spindle down to a nice
smooth 4-8 rpm, to use as a powered spindle for hand figuring, which is
where a DC variable drive comes in nicely.

Just my personal preferences 


Bill
---

Bill & Tracy Marriott
Woodacre, Ca. USA
btk@pacbell.net

http://www.starlightoptical.com
optical/telescope stuff