Electric motor for 9" disc sander/grinder?

Danbo

Danbo

Joined
Nov 28, 1999
Messages
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Ok, so I went ahead and bought one of those 4140 steel 9" discs that Rob Frink sells. Now, I need to wire up a motor of some kind. This is where you experts come in. I have no idea as to what kind of motor to use. How powerful do I need? How fast should it spin? Variable speed? Mounting to what? Help! :)
 
Get a DC variable speed setup with the appropriate shaft size (5/8?).You will love being able to slow it down.You don't need a big motor 1/2 to 3/4 HP is plenty.You can get good deals on these motor/controller combos on Ebay and the surplus sites.
 
agreed...


Also wanted to add....

You could also go for a 1750 rpm AC motor and use step pullies to get different speeds. (cheap/easy) 1HP is more than enough.
 
Ok, dumb question time. I also need a decent buffer. Can I buy one of those 3/4 hp Baldor buffers and use one side for the disc and the other side for the buffer?
 
Yes - but there's a good chance it will be moving too fast for the disc, and/or too slow for the buffer.
 
I have found a few new Leeson Speedmaster controllers with forward/reverse/brake on Ebay for good prices. I went with a 1.25 HP Leeson DC motor from Surplus Center for the latest motor (mostly for flat grinding blades). It was $139. If you are mainly working handle material, bolsters, guards, etc. 1/2 or 3/4 HP is fine. Rob Frink recommends 1HP as a general rule.

John Frankl
 
Daniel Koster said:
Yes - but there's a good chance it will be moving too fast for the disc, and/or too slow for the buffer.
Click to expand...

I saw a 3/4 hp Baldor buffer that spins at 1750. Sound good?
 
If it's a good price - go for it.


1750 is the fastest I would want to go on a disc grinder...and the slowest I'd want to go on a buffer. Most of the flat-grinding I've done on one (not my own) was done at 500-1200 rpm. Most of the buffing I've done in my shop has been at 2000-3500 rpm.


You can get by on the buffing side by getting large wheels - 10 to 14 inches in diameter...which will move faster at the perimeter than a small wheel.


For grinding....you'll just want to develop that soft touch needed for high rpm operations.
 
Danbo said:
I saw a 3/4 hp Baldor buffer that spins at 1750. Sound good?
Click to expand...


Keep in mind that the Baldor buffer, if it's an actual buffer and not just a motor has 3/4" shafts. Most disks have 5/8" arbors.

I've been using the 332B, 3/4HP Baldor 1800RPM buffer, as a buffer, for many years. It's never once failed.
 
Daniel Koster said:
agreed...


Also wanted to add....

You could also go for a 1750 rpm AC motor and use step pullies to get different speeds. (cheap/easy) 1HP is more than enough.
Click to expand...


What are you running a belt and pulley to? Are you talking about a seperate shaft and pillow blocks to mount the disks too?

I've been using two 1750 RPM AC motors for disk sanders for a long time. It's worked well. The HP on mine are 1HP, but you can get by with 3/4 well.

I recently switched out one AC motor for a 1HP DC VS, but haven't used it yet. I'm going to switch the other AC motor out to VS shortly, and hope I get a chance to use them.
 
nice pic, Mike!

(nice setup too!)



Yes...I was referring to a pillow-block setup...but actually had vertical in mind...thanks for the clarification.
 
Thanks Mike,

How far over the edge of the bench do you like to hang your disk? And how high do you like it mounted?

John
 
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