Why bigger drive wheels

Chris Railey

Chris Railey

Well-Known Member
I know larger drive wheels mean faster belt speeds but please tell me where it would be better to have very high belt speeds. What operations benefit from a screaming fast belt? Remember I only have a one speed grinder so I do everything as fast as my grinder will go.
 
Chris, when my grinder was a single speed I had two drive wheels and could change to the big wheel in less than a minute for hogging steel and primary grinds and then to the smaller wheel for the finer belts to keep the burn factor at bay.
 
Ok, so faster for hogging and slower for finish. I do that now varying pressure and dunk frequency. Other than hawging steel I was curious if high speed helps anything.
 
My pal uses a larger drive wheel but boy is it scary fast. He had a 36 belt hit him in the chest, hit like a hammer and cut him. He is braver then me ))
 
It's not about the size of the drive wheel - well, not only anyway. What you're looking for is belt speed. For ceramic belts you really want something more than 4,000 SFPM to make them really work. 6,000 SFPM and ceramic really comes into play with pressure. With an 1800 RPM motor (direct drive) it takes a 9" drive wheel to get 4200 SFPM belt speed.

Let's consider shaft RPM (same as motor RPM in direct drive). With a 4" drive wheel the belt SFPM is a tad more than RPM;
1800 rpm = 1880 SFPM
3600 rpm = 3770 SFPM

With 5" drive wheel
1800 rpm = 2350 SFPM
3600 rpm = 4712 SFPM
4,000 rpm = 5236 SFPM

With 6" drive wheel
1800 rpm = 2827 SFPM
3600 rpm = 5665 SFPM

You can see why the 1800 rpm motors have to use the 2X jumpers they talk about so they can run the motors up to 4,000 RPM same as the 3600 rpm motor. Remember the 1800 and 3600 numbers are the "thericatical" speeds, not the actual speed. All motors have some slip, and the actual rpm for an 1800 rpm motor will be in the 1725 to 1750 rpm range as a general rule.

I think perhaps the perfect setup would be a VFD with 1800 rpm motor with a 5" drive wheel giving a range of speeds frm 300 SFPM to 5200 SFPM belt speed.

Perhaps more than you wanted to know about drive wheel size:)
 
Last edited:
KenH said:
It's not about the size of the drive wheel - well, not only anyway. What you're looking for is belt speed. For ceramic belts you really want something more than 4,000 SFPM to make them really work. 6,000 SFPM and ceramic really comes into play with pressure. With an 1800 RPM motor (direct drive) it takes a 9" drive wheel to get 4200 SFPM belt speed.

Let's consider shaft RPM (same as motor RPM in direct drive). With a 4" drive wheel the belt SFPM is a tad more than RPM;
1800 rpm = 1880 SFPM
3600 rpm = 3770 SFPM

With 5" drive wheel
1800 rpm = 2350 SFPM
3600 rpm = 4712 SFPM
4,000 rpm = 5236 SFPM

With 6" drive wheel
1800 rpm = 2827 SFPM
3600 rpm = 5665 SFPM

You can see why the 1800 rpm motors have to use the 2X jumpers they talk about so they can run the motors up to 4,000 RPM same as the 3600 rpm motor. Remember the 1800 and 3600 numbers are the "thericatical" speeds, not the actual speed. All motors have some slip, and the actual rpm will be in the 1725 to 1750 rpm range as a general rule.

I think perhaps the perfect setup would be a VFD with 1800 rpm motor with a 5" drive wheel giving a range of speeds frm 300 SFPM to 5200 SFPM belt speed.

Perhaps more than you wanted to know about drive wheel size:)
Click to expand...
Not at all Ken that helps me decide, thanks.
 
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