bandsaw motor question!

[tracy myerson]

hi folks,

this is my first post here, i find you all so helpful i'm hoping you can shed some light for me!

i bought a restored 20" rockwell bandsaw recently. it has a 3 ph 1 hp motor, with a secondary 3 ph 1.5 hp motor acting as the static converter / "idler" to make it work in my single phase shop. due to a mishap, i blew up the capacitor and seem to have burnt out the auxillary 1.5 hp motor. possibly damaged the initial motor too but i don't know. repairing it is going to be expensive, and 1 hp seems small for a 20" saw that i am going to use for re-sawing. so i am thinking to just get a single phase motor, maybe 3hp if i can find one. so my question is can i simply install a new 1 ph 3 hp motor? i know i may need to change switch and wiring. it is on a 2 pole 20a breaker so that shoud be fine. but my main questions are about the motor swap. does the frame size matter or can i just remount a new motor and drill new mounting holes? does shaft dia. matter? as long as i get the same rpm (1725) and same size pulleys? does belt length matter?

admittedly i know very little about motors! lots of research but still can't find answers to these questions. i gather new pulleys are easily found at any auto store, i could replace belt with link belt but not sure how to calculate belt length from final position? the original motor is a 203 frame which is hard to find used and i have no budget for a new motor... hoping to find something decent on CL (i am in the middle of nowhere canada!)

any and all advice and expertise would be so greatly appreciated! i am just getting started making furniture, but setting up my shop is quite overwhelming, as i know how to use the machines but not set them up or tweek them! and then there s the electrical stuff which is not how my woodworkers brain is wired!

thanks in advance, i am super grateful for anyone's help here! cheers, tracy

[Mike Heidrick]

You can use anything you want but keeping teh same frame will help in getting it done easily

Mount
speed
rotation
shaft dia
shaft length
keyway type
wiring
phase
rated use


All things to keep in mind

Buying new caps is pretty easy to do. How elese did you damage the motor?

A VFD is fairly cheap and would power your 1hp.

Spend the money to do it right and if you cant afford to wait till you can. Making another motor work rigged up will most likely cost you more in teh end and that cost might very well be performance of the whole saw.

Ebay has pulleys for cheap

[tracy myerson]

Thanks Mike. I replaced capacitor but nothing is working hence my assumption that I burnt out motor. I don't want to figure out how to wire VFD. I just thought that 1 HP seems small for a 20" saw, if I am spending money to fix it why not just get a bigger motor. Better in the end not worse, no? Trying to spend my money intelligently...

[Erik Manchester]

Tracy, a VFD is simple to wire up and needs less expensive switches than a motor does. A VFD to fun your saw is cheap and almost plug n play. Teco FM50 would do it easily as you are not looking at speed control. A lot safer than farting around with a shop made phase converter.

[tracy myerson]

Thanks for the reply Erik. Problem is $130 USD for a VFD and I still have a 1 HP 20" bandsaw. Makes no sense to me when I can find a used single phase motor for that... I'd like to up the power on the saw if I am going to spend the money. Was hoping for some help on how to make the swap. I know speed matters, shaft size does not, frame not really I can adapt what is there. Get same pulley ratio, need different switch. Same rotation direction, already wired on 2 pole 20A breaker which will run up to 3 HP no prob. Just wondering if I missed something? Starting to seem more and more simple but I am not an expert! Cheers

[Malcolm McLeod]

Advise you don't overlook the physical strength of the frame and wheel bearings.

When you increase Hp, you obviously get more torque, and the blade pulls harder when feeding stock. But for every action, there is equal and opposite reaction. This will result in increased deflection of the frame, only detectable while you're cutting.

How much Hp is too much? How much deflection is too much? At 1.5Hp, increased deflection might be nearly undetectable? At 3Hp, be prepared! I don't know how much extra strength or safety margin is built into the saw, but I would see if this saw was ever offered with a motor similar in size to your proposed upgrade.

(FWIW - I'm in the VFD camp.)

[Allan Speers]

Thanks for the reply Erik. Problem is $130 USD for a VFD and I still have a 1 HP 20" bandsaw. Makes no sense to me when I can find a used single phase motor for that...

Except the VFD also give you variable speed, dynamic braking, (which can be increased by adding larger resistors) soft-start, and motor / operator protection much like a mag-starter. Also, 3ph motors have much less maintenance issues over time.

Still, I'd want more than 1 HP. What's the re-saw height capability?

[Tom M King]

2 hp is common on that saw, and was the original motor on the one I had.