Need to make a decision on a drive wheel size

G

Grayzer86

Joined
Jan 15, 2012
Messages
1,209
Hey guys I am in the process of converting my 2x72 to variable speed, and need some input. My plan is to obviously run direct drive to get away from the extra noise and vibration of a shaft and pulley setup. I currently have a 2hp 3 phase baldor industrial that runs 1800 rpm. With a teco fm50 in filtered cabinet and a potentiometer. I already have a 6 inch drive wheel currently on my grinder but it is 5/8 bore. The new motor has a 7/8 shaft, and with nobody near by to bore it for me, I will just buy a new drive wheel. I just can't decide between 4 or 6 inch. A 4 inch wheel would give me roughly 1900 fpm at 60 us and 3800 max at 120hz. A six inch wheel would give me about 2800 at 60 and 5600 at 120. I doubt I will need 5600 but wonder if 3900 will be enough on the top end for heavy hogging. I'm leaning more toward the 4 inch wheel so I don't have to drop the hz as much to achieve slower speeds as I don't want to run the motor too low, but also don't want to have to drive at 120hz all day for profiling either. What say the experts?
 
I would go with the bigger wheel. You can always slow it down with the vfd and at slow rpms you are hardly likely to be pushing hard enough to bog it down. Premium ceramic belts however generally demand a high sfpm to achieve best performance.
 
One thing to consider is at slower speeds, you will need very little power as slow speeds are usually used for the "tender" touch. higher speeds are using for profiling, just how much of the time will be profiling with heavy "hogging" vs the time spend with slower speeds? I find I cut pretty close to the profile with a porta-band saw, so very little time is spend hogging vs time spend with slower speeds for more precise grinding.

Ken H>
 
I run all my grinder with 6" drive wheels and do not over speed them through the vfd when I send them out. This seems to work very well for my customers. I did run the 4" drive wheels for awhile and during testing and much preferred the over all performance of the 6" drive wheel.

Brett Mathews
Esteem Grinders
 
what kind of knives are you making. im running a 4 inch drive wheel on a VFD and when hoggin with 50 grit i run it at 80hz but i make razors and kitchen knives i cant press hard and i cant use even part way dulll belts for fear of over heating blades. i give my "used belts" to friends that smith and make heavy blades
 
Thanks for all the input guys. Being that the vote was pretty much all for 6 inch that makes my decision pretty easy. I guess now I just need to track down a 7/8 bore wheel and order my VFD and I should be off and running. Thanks again
 
6" gets you enough speed without the 2x option. You can always slow it down. Keep in mind that when you slow the motor down, you also slow the fan down that cools the motor.
 
Last edited:
I run 5400 with a 6 inch drive wheel powered by a 3hp motor. At that sfm I choose to run good belts; don't want anything coming loose at that speed. At 5400 it is a joy when grinding bevels where you want to remove a lot of metal.

Fred
 
You must log in or register to reply here.
Back
Top