Horizontal disc grinder motor

K

Ken Kelley

Joined
Mar 6, 2007
Messages
106
I am researching motors to use for a low-speed horizontal disc grinder. I'm an electrical dummy so I'm fair lost in the weeds in this subject area. However, I do understand dimly that DC motors are best for applications requiring torque over speed and found this motor on Ebay, Item # 150231105735. It appears to be what I need but before I plunk down money I would like to know what those of you with electrical experience think of this machine.

Thanks,

Ken
 
That is a gear motor rated at 50rpm with only 8.5ftlbs of torque. the shaft is only a little over a quarter inch. Way to small for lateral loads required on a disc. Then you need a DC power supply to run it, that can be big bucks. I do not think this will do what you want. You may be able to get it to work but if you pick up a 1hp 56 frame you can slow it down to 15-20 rpm and still have plenty of torque.
I have found 3ph provides better torque over DC. 3ph is also less expensive to set up. I have both a 1hp DC and 3ph AC. I really like the DC but Love the AC 3ph. I can slow it way down and put some pressure on the face. DC set ups can be very expensive to set up. 3ph AC can be easier and cheaper. You can find a 3ph motor on ebay for less than $50 + ship. Then a Variable Frequency Drive will cost about $250-$350 new. total set up for a 3ph should be way under $500, that is if you do not wait for the deals.
 
Thanks for the advice. You've saved me some disappointment. I will see if I can find motors like you suggest. I'll do some Googling and educate myself in more depth on the motor issue.

Ken
 
Your post on the benefits of the 3 phase over DC led me to do some serious poking around on the web. Came up with a bunch of info on the the subject that I think might set me on the track. There's a site called the Practical Machinist that has a subforum devoted to VFD, phase converters, transformers, etc. The VFD portion is informative.

It sounds like your way is definitely the way to go. It certainly makes economic sense to spend a bit on a VFD unit then be able to get the motors for a song in comparison. I'll do some more research and then start looking for equipment.

Thanks so much for getting me pointed in the right direction. Your comments have been valuable.

Ken
 
Great.. Thanks for the feedback and the name of the forum. Looks like another bookmark for my computer.
 
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