variable speed question

Mr. Bat, On my main grinder I used a variable pulley setup that provides for infinite adjustment between 1500rpm and 5600rpm. It is basically 2 cone type pulleys, one on a movable arm that moves to provide adjustment. If you prefer mechanical things to electrical this may be a good option. I can't recall at this moment the brand name, but you can find similar pulleys on ebay with a little effort.
If you look at old threads, you can see the pics of my setup.
Good luck.
Alden
 
The control you linked to only "works" with universal motors. Those are the motors with carbon brushes usually found in power tools like sanders, drills, routers, etc...So unless you are powering your grinder with a router or a motor out of a vacuum, it won't work.

It's also a good way to burn up a universal motor to use a control like that and then load the motor at low speed.

If your grinder has a 240V 3 phase motor you can add variable speed by buying a Variable Frequency Drive, about $300. You can sometimes get used 3 phase motors pretty cheap, and a VFD will run a 3 phase motor on single phase power. If your motor's not "inverter grade" it will eventually die if you run it loaded at low speed a lot...but it will last with light use for a while. If your motor is single phase, and a new motor and VFD are too much $, look at split pulleys or step pulleys or other mechanical means of speed control.
 
Thanks for the input, have step pulleys now, I think I will just wait until I can afford the proper VFD setup.
 
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