Replace motor on 1982 BusyBee Knee mill

[sean69]

hi all, I was wondering what an appropriate replacement motor for a 1982 BusyBee knee mill would be.... the current one burned out (in a big puff of smoke) it is a 1.5Hp 115.230v 1 phase 1420/1720RPM motor (Leader mod. DY-35 via Deng Yuan Industrial Co. Ltd. if anyone is interested)

So there are a LOT of motors out there that fit the above description, but I was concerned with what sort of torque, duty cycle etc. a mill needs and how to figure that out when going to buy a new motor....

Any suggestions?

 

[machPete99]

Cheapest is to find a similar motor/frame with similar shaft size/length.
I you want to improve things (but more $) consider 3 phase with VFD.
Getting a larger motor with more poles gives you better low RPM torque, which is useful on mills with no back gear.
6-pole motor will be nominal 1200 RPM, but is typically heavier for equivalent HP.
Better motors will have better insulation, like class-F which can handle VFD heat better.
Also look at bearing sizing, bigger is better.

 

[sean69]

Cheapest is to find a similar motor/frame with similar shaft size/length.
I you want to improve things (but more $) consider 3 phase with VFD.
Getting a larger motor with more poles gives you better low RPM torque, which is useful on mills with no back gear.
6-pole motor will be nominal 1200 RPM, but is typically heavier for equivalenet HP.

Thanks! that's a lot more info than I got from even the manufacturer!! also brings up a couple points.

Cost is a factor Mill was going to be sold anyway, but can't be sold sans/motor.
needs to be switchable from 115/230 - I have not seen anything larger than 2hp that can be switched. (between voltages)
this one is a 4 pole motor or was as it stands.

THANKS!

 

[mksj]

You need to check the motor name plate as to the motor specifications and ideally some information as to the motor frame type. If it is metric or US frame, also the motor shaft diameter and length. Since the motor bolts to the mount and the shaft length seems to dictate the pulley height, you need to match up something with the same dimensions. If it is a US frame just about anything will work with the same frame, most of the motors in this size are dual voltage. Check Amazon, Craigslist, etc., if it is metric or some odd size mount/shaft then check the manufacture, Grizzly, or similar vendor. If cost is an issue, then check the used market around you.

 

[sean69]

I got the original information off the data plate ... have not measured the shaft yet. truthfully the mount was the least of my concern as between the 2 of us we can make/weld/modify whatever to fit.

But now looking at the pictures, the mount is quite heavy duty. looks like 1/4" cast as part of the motor housing. mmmmm ... something to consider.

 

[matthewsx]

It does look like some sort of standard frame size, take it off and measure. You can make a spacer plate if needed to get the shaft in the right location, or change the belt.

New owner will appreciate changing to a three phase with VFD, makes speed changes way easier.

Of course you could always get the original rebuilt if you have a local motor shop that does this kind of work.

Cheers,

John

 

[sean69]

It does look like some sort of standard frame size, take it off and measure. You can make a spacer plate if needed to get the shaft in the right location, or change the belt.

New owner will appreciate changing to a three phase with VFD, makes speed changes way easier.

Of course you could always get the original rebuilt if you have a local motor shop that does this kind of work.

Cheers,

John

Not my mill, so I can't say if an upgrade is gonna happen, though I kinda own that motor burning out (my buddies mill) wondering what could cause that though... was running for about an hour maybe + 1/2 .. milling a piece of 12-L-14 steel, pretty heavy roughing cuts, but the chips, tool and work were all cool to the touch (well cool enough to be able to touch and hold without discomfort) no discolouration on the chips and no smoke from the chips.... I did notice that starting it would take a good 10 seconds to spin up to speed - at one point I actually had to give the cone pulley a spin with my hand to get it going (clue #1) - like I said no smoke from the chips, but the garage started smelling like it when I looked up see smoke (clue #2) then the motor made a big sigh like a release of steam and big puff of smoke and stopped........

so I kinda own that for not realizing smoke means fire and that having to bump start a mill is not a good sign (or particularly safe)

What could those symptoms indicate?

 

[matthewsx]

Have you checked the starting caps?

 

[sean69]

Have you checked the starting caps?

I do not know what a starting cap is!! ( so "no" )

 

[matthewsx]

Starting caps (capacitor) provide a "charge" as it were to get the motor started from a dead stop. They're usually under one or two rectangular covers on the outside of a motor. The other thing that can fail is when a coil winding shorts out internally but the cap is the first thing to check.

Motor starting capacitor | Applications | Capacitor Guide

Motor capacitors AC induction motors use a rotating magnetic field to produce torque. Three-phase motors are widely used because they are reliable and economical. The rotating magnetic field is…

www.capacitorguide.com

If that's your problem it's usually much cheaper and easier than replacing the whole motor.


So, if you were borrowing it why aren't you offering to buy it from him anyway?

John