Pulley size needed?

[Hawk45]

Going to order a 3HP 3PH 1740 and VFD. I'm going to hook it up to my 2x42 with pulleys till I can save up for a full size grinder. I'm decent on the 2x42 now, so figure I'll get a good motor and VFD that will give me more speed/power control over it. Then I'll be able to move over to a full size grinder when cash comes available.

Anyway, have a few questions before I order parts:

1.Pulleys:
A. I know what inside dia. sizes, but what outside dia should I get for the motor side and the grinder side. Again, I'll have a VFD so no step pulley needed.
B. Also, what v-belt size/spec should be used? 24" A Series? (as long as it matches the pulleys)?

2. VFD: (KBAC-29 3HP NEMA 4X VFD 230VAC 1PH INPUT 10001)
A. I see options for the VFD and wondered if I should add any of these to the order, if they are important:
1. On/Off AC Line Switch:
a. Yes
b. No
2. Forward-Stop-Reverse Switch:
a. Yes
b. No
3. Signal Isolator Options:
a. Signal Isolator with Auto/Manual Switch
b. Signal Isolator without Auto/Manual Switch
4. Liquidtight Fittings:
a. Yes
b. No

Thanks guys!

Thanks,
John

 

[12345678910]

You do need to add an on off switch.


I like using a cable gland to seal the wires coming in and a switch boot to cover the switch (home depot)

A local electrical distributor will have stuff and have it much cheaper than KB will sell it to you.


If you plan on using that vfd to power a disc grinder then forward / reverse will be important to you also



With regards to the pulley ratio.
A non inverter duty motor loses torque at low speed.
The vfd manual has a nice graph of that.

It makes sense to me to use a high gear down ratio that runs the motor faster so it hits a better torque band, while running that sander slower

direct drive setups usually run with a 3600 rpm motor
Having a 1700 rpm motor usually means running a ratio that doubles speed on the top


However a 3 HP motor may make up for that torque loss and not be an issue.

 

[Hawk45]

Thanks brother!