Anyone ever use a variac on a belt grinder?

hathegkla

hathegkla

Joined
Feb 3, 2010
Messages
201
I've never tried it but I have one sitting around somewhere I might dig out. I've got a Grizzly belt grinder on the way, I know these are a bit fast for working after HT. I'm wondering if I could slow it down with a variac for sharpening? or should I just use my cheap little harbor freight 30" belt grinder for that?
 
Curious. I have wondered the same. Make a small box with a cord, outlet, and variable speed ceiling fan rotary switch in-between. Surely it would slow it down, but it might also lose power as well.
 
that what I was thinking, I'd lose torque. though I already have a variac so it wouldn't cost me anything, I'd just have to find it.
 
I'd say don't loose your time finding it then. Not gonna work. Or else people wouldn't spend big bucks on Variable speed drives, myself included. ;)

Patrice
 
Listen to Patrice. You can easily stall a Grizzly if you're trying with it running at full power. On a variable AC, it will be all but useless.

--nathan
 
On a Variac you will be basically giving it a brownout condition (decreasing the voltage without changing the cycle frequency) It will try to make up for the missing voltage by trying to draw more current under load, the windings are set up for 3300RPM (60cycle - inductive field slip)

You will not effectively drop RPM like you would on a shaded pole motor, you will just smoke the windings either on your motor or your variac. You need to keep the voltage up and change your cycle frequency to change RPM on that design of motor

-Page
 
Grizzly sells a 10' wheel, which I assume is larger than the standard size and would increase the belt speed. Could the Grizzly grinder be slowed with a smaller drive wheel?
 
jurisprudence: yes, very easily. however you would run into clearance problems if you plan on using the contact wheel. I think the grizzly comes with an 8" (I'd have to go out and measure mine). whatever comes stock has decent clearance but any smaller would be bad. if you're just using the platten or slack belt go as small as you want.

honestly I just tried mine out for the first time yesterday and didn't think it was too fast at all. it doesn't heat the blade up too much on one or two passes. I always keep a cup of water nearby anyway. I don't really see a need to change the sped at this point because I'll still be using my little 30" for sharpening since I still have a lot of belts for that left.

sunshadow said:
On a Variac you will be basically giving it a brownout condition (decreasing the voltage without changing the cycle frequency) It will try to make up for the missing voltage by trying to draw more current under load, the windings are set up for 3300RPM (60cycle - inductive field slip)

You will not effectively drop RPM like you would on a shaded pole motor, you will just smoke the windings either on your motor or your variac. You need to keep the voltage up and change your cycle frequency to change RPM on that design of motor

-Page
Click to expand...

whoh, good info. thanks for the warning.
 
You must log in or register to reply here.
Back
Top