On Jul 20, 1:16 pm, " wrote:
On Jul 20, 4:39 pm, mlcorson wrote:

I just got this Rockwell 1970's sander. It has a 3/4hp, 3420 rpm motor
on it. This seems very fast to me. What size is your machine side V
pulley? What rpm is your motor? I went to the Delta/Rockwell website
and found the specs. They call for a 3400+ rpm motor. My machine may
have the wrong size V pulley. Any information is appreciated. Thanks.
_mike

My motor looks to be the original motor, has a Rockwell id plate on
it. It is 1/2 hp 3450 rpm. The motor has a pulley that is just
slightly bigger than the pulley that drives the belt. OD of the motor
pulley is about 3 inches.

Hope that helps.

Dan

George and Dan:
I've wrapped the drive wheel with rubber tape (thanks George). Worked
great. I replaced my back idler wheel with a skate board wheel (Thanks
Martin). Everything is working beautifully. However, I still would
like to have some variability in the belt speed.
The grinder is mounted on a vertical tube stand with the motor
attached to the tube below the grinder. The following options seem
practical. I have an variable speed spring loaded pulley that I
removed from one of my folding machines. The spring loaded motor
pulley (was on the motor) seemed to work by increasing/decreasing the
tension on the belt. I'd have to engineer a tensioning device to make
the pulley work in a 3rd position on the belt. Make sense? The other
way is to use 2 cone pulleys, one on the motor and one on the
machine. I'd "hang" the motor on a hinge and use the weight of the
motor to put tension on the belt. That way the motor is simply lifted
to release the belt tension, and change the pulley arrangement.
Downside to any of these approaches? What about a static cone pulley
in a 3rd position? How would I move the cone to align with the belt?
My first observation is that there is very little room for a larger
pulley on the machine side. Maybe room for a 4". Honestly, I don't
know think I have the skills to construct an idler with a shaft and
bearing. I'd have to find something and adapt it my use. What think?
-Mike