2 x 72 home build pulley suggestions

G

Goblin13

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Dec 26, 2016
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Hello all, I am building a 2 x 72 belt grinder and need suggestions on the proper set up of a pulley for my 3450 rpm motor. The 5" contact wheel will be mounted on one side of a bearing stand and on the other side will be a step pulley with 2", 3", 4" and 5" steps. What pulley size would you recommend to attach to the motor to get a good usable fpm range for grinding knives? I only have room for a single pulley on the motor.

Thank you all in advance for the advice!!!
 
You didn't mention what size your drive wheel is. Making the assumption it's a 4" drive wheel, then with your 2-3-4-5" pulleys on the shaft, a 2" pulley on the motor would give you around 3600 SFPM, 2400 SPFM, 1800 SFPM, and 1450 SFPM selection of speeds (in the order of shaft pulley 2-3-4-5").

A direct drive with a 3600 rpm motor using a 4" drive wheel would give you "around" 3600 SFPM belt speed as your only speed. Just fine for profiling, but sure would hate that to be my only speed.

Now "IF" that is a 3 ph motor, then by all means direct drive is the only way I'd consider it with VFD drive.

Ken H>
 
Ken H> said:
You didn't mention what size your drive wheel is. Making the assumption it's a 4" drive wheel, then with your 2-3-4-5" pulleys on the shaft, a 2" pulley on the motor would give you around 3600 SFPM, 2400 SPFM, 1800 SFPM, and 1450 SFPM selection of speeds (in the order of shaft pulley 2-3-4-5").

A direct drive with a 3600 rpm motor using a 4" drive wheel would give you "around" 3600 SFPM belt speed as your only speed. Just fine for profiling, but sure would hate that to be my only speed.

Now "IF" that is a 3 ph motor, then by all means direct drive is the only way I'd consider it with VFD drive.

Ken H>
Click to expand...

I think he meant to say 5" drive wheel, instead of contact wheel?

Eitherway, I'm not sure how you'd effectively go from a single step pulley to a 3 or 4 step pulley... The single pulley would only be aligned with one, maybe two steps of the step pulley, and even if you split it between 2, you'll have uneven belt wear and other potential problems. Not to mention, due to the varying diameters of the additional pulley steps (and the single diameter of the one) the belt length will need to change for each, or the motor will have to be moved back and forth, and re-tensioned.
An intermediate shaft would be my solution, if you absolutely HAD to use a 3450RPM motor with a short shaft. If space is an issue, mount the motor under the bench, and put the intermediate where the motor would have been.

Or maybe I'm misreading the entire post. When you say single pulley, you mean ONE single v-belt pulley, right?
 
To use a single 2" drive pulley, he needs to make a sliding mount for the motor. It is prety easy to do. A piece of 1/2" round stock, two 3" pieces of 1/2" ID pipe, and a steel plate for the motor to bolt to are the main parts. Since it also acts as a hinge, a bungee cord or spring applies the tension to make fast belt speed changes.

The other way is to have the same pulley type on the motor as the grinder, with the direction reversed. Usually it is a 2-3-4/4-3-2 and that will give you three speeds of 50%, 100%, and 200%.
 
Yeah the drive , not contact is 5" and I am going to make it to be able to slide the motor for each step. I would love to have a 3phase motor with VFD but will have to get that later. So a 2" pulley on the motor, because I only have room for one, seems to be what I would need for now I guess.

Thank you for the input all!!!!!!
 
OK, with a 2" motor pulley, and a 2-3-4-5 inch diameter shaft pulley with a 5" drive wheel, here's what you'll have:

2-3-4-5 inch shaft pulley will give 4516-3011-2258-1806 SFPM belt speeds.

Ken H>
 
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