Why Are Tool Post Grinders Belt Driven?

[John McClanahan]

I'm thinking of making a mount to use my Foredom rotary tool with the collet hand piece as a tool post grinder. All commercially made grinders are belt drive. Is there a reason for this?


John

[William M Johnson]

Cost. A powered spindle suitable for use a a grinder would be $$$$$$$$$$.

Bill

[andy bessette]

They're belt driven to make it easy to change pulleys and speed, and still get full power.

[David Stine]

Two reasons:

1. You can change speeds by changing the belt pulley ratio(s).
2. Vibration isolation. There are two reasons to be using a toolpost grinder: the first is to hit a very specific size, and the second is to obtain a good to very good finish.

[Kevin Beitz]

Biggest reason is so the motor is not in the way....

[Bill Dufour]

Most are single phase so the belt drive helps smooth out the pulses which can be visible in the work.
Bil lD

[Alan Heffernan]

Also to get the motor drive out of the way and provide space.

[Kevin Beitz]

My unit is direct drive. No belt...

[Roger Feeley]

John, you can use the Foredom if your work is small and needs are infrequent. I have used my Foredom on my Sherline lathe as a grinder and it was fine. But the work was very small. I can't remember where I got the holder for the Foredom but I didn't make it. here's an ebay link for one. (https://www.ebay.com/itm/The-ORIGINAL-Lathe-tool-holder-for-Foredom-flex-shaft-hand-piece-/112030971540)