Belt vs. Direct drive

D

DukeHarley

Joined
Apr 11, 2014
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Did a quick search but couldn't find the answer I was looking for. Just wondering since I'm in the beginning stages of building a 2x72 grinder as to what are the main advantages and disadvantages of a direct drive vs a belt drive. Why do some of you choose one over the other......and does it really in the big picture make a noticable difference?

Jay
 
Belt drive allows a multi-pulley that will thus allow speed change. It is cheap and works well. Vibration can be a problem. Machined steel pulleys and a link belt will lessen vibration. Belt drive needs a tension method and takes up more space.

Direct drive has less vibration, and takes up less space. It would require VS for any speed change. That would require a Dc or 3Ph motor and a controller.
 
Ok thanks. I was talking with a guy here at work and he said a belt drive is smoother. I disagreed because its more moving parts and if there is any runout or slop in the shaft or pullys it could be felt through the whole set up. You answer was what I had thought. I knew that you'd have to go belt drive if you didn't have a variable speed control and you wanted rpm options but I noticed on YouTube that there were guys out there that had grinders with belt drives that had variable speed controls on them and was curious as to why someone might build it from the ground up belt driven with a variable speed control. Didnt know if there was something else I was missing or not.

jay
 
Direct drive will require the motor to be C-Face also . . . Lesson & Baldor both offer C-Face kits to convert if you already have a motor.

Also direct drive makes it far less complicated if you are designing a grinder that will operate both vertically & horizontally.

My "opinion", if you are choosing direct for power transmission alone, you will be disappointed.

I have built different types of equipment over the years using standard v-belts & cogged belts v-belts.

I can assure you that the 2" X 72" smooth back abrasive belt will slip before a "PROPERLY TENSIONED" V-Belt will . . .

A link belt will make that even less likely to happen . . .

Steve
 
Direct drive is also much quieter in my experience.
 
Yes I'm planning on building it to be used in both vertical and horizontal positions. I have all the steel cut and squared at work just gotta pop holes. It's going to be my winter project after bow season ends.

Jay
 
I built my grinder direct drive because it was fewer parts. I plan to build a couple more grinders soon and they will be direct drive.

sdemars said:
Direct drive will require the motor to be C-Face also
Click to expand...

You "could" build a direct drive grinder without using a c-face motor.
 
I gotta comment because I now have both types, almost. ( I am building a GIB direct drive grinder right now in addition to my other grinder, a KMG with a belt drive. My new grinder which will tilt horizontally will use a 3450 RPM motor with 2 poles driving a 4 inch wheel for about 3600 surface feet per minute. My Kmg with pulleys and jackshaft uses a 5" and a 2 1/2" pulley to double the speed of a 1725 RPM motor that has 4 poles to 3450 RPM driving a 4 3/8 inch drive wheel for about 3960 surface feet per minute. I am no electrician but many people have told me that the 1725 RPM 3 phase 220 volt motors are better and produce more power throughout their speed range than the 3450 RPM motors. This may be no big deal but I decided on a faster motor for my tiltable direct drive application. Yes, I know that you can get bigger drive wheels to produce more speed but a 6 inch wheel would not give me the speed that I think I might need. I have probably overthought this like I often do but that is the rational. I use VFDs on everything in the shop. Larry
 
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