Re: ATM - More Grinding Machine ideas

[Dennis Rech <dennisrech@home.com>]

>Steve (and everyone),
>
>I'm a little bit familiar with the M-O-M, Dennis's
>machine is very well thought out, and I've been doing
>about half of my research on grinding machines in his
>online operator's manual.
>
 Also, I'm
>not convinced that all of those speeds in the M-O-M
>are necessary, a single mirror/tool movement ratio and
>a few spindle speeds at most seem all that is
>necessary (go ahead, flame away everyone).  

Hi Adam,
Just writing to let you know that I agree with your convictions. I usually
recommend a single turntable speed of about 80 rpm for grinding and polishing.
If you will be using the eccentric (it helps to have a little occillation) it
should be about 40% of the rpm. You will find figuring to need a much slower
turntable speed and faster arm if you use normal figuring techniques. All the
speeds of the M-o-M are there for a reason, but most people will have little
need for them. They also cost nothing extra if you don't buy the additional
small pulleys.
Some people have requested dc motors but I just cannot justify the added work
and cost for so little gain. 
I believe that you found a 825 rpm motor. These are an excellent speed, but
rather rare and expensive if bought new. That means that you only need a
single
stage of 11 to 1 reduction to obtain usable turntable speeds. I've found
that a
1.5 inch driving pulley is about the smallest that you can get a 1/2 inch belt
to turn around. That will mean that your wooden driven pulley will be about 16
inches in diameter. Certainly a practical size. If you can find a 60 degree
router bit, you can make a usable v. Without the v, it will take a mighty
tough
idler pulley to produce enough torque. 
I am looking forward to seeing what you come up with.
Dennis

Dennis Rech
Mirror-o-Matic

http://www.oblivion.net/~astro/mirror/