Need advice on sizing a motor capacitor for a Jet horizontal band saw

[rons]

Does appear to be two capacitors. The plastic wrapper around the can tin the second picture does not match the first picture.

 

[Randalthor]

It's unclear to me how many caps this motor has. The OP states that the cap in question has a dent in it. If so, it's a run cap...

Sorry for not providing that info, which leaves people to have to guess. Below is a fuller pic of the motor. I banged out the dent in the cap cover.

The motor is not a dual voltage motor. The manual states that the motor is single phase 230v.

The next size saw down uses a 115/230v motor, but this saw says it's a straight 230v on the motor nameplate and in the manual. Additionally there is no neutral which goes to the motor. Just straight L1 & L2.

 

[Randalthor]

Does appear to be two capacitors. The plastic wrapper around the can tin the second picture does not match the first picture.

I undid the wrapper in the second pic, so it possibly makes it look like it could have two tin cans. But there's just one can. Sorry for the confusion.

 

[SAF]

I would suggest removing the motor and cracking it open. If the start switch is burned up, a cap alone won’t do you much good. Finding a centrifigal start switch to fit it will likely be more difficult than a capacitor. They do make electronic ones today but that requires some modification.

A different motor could be a cheaper option once you know the dimensions of that one.

 

[Randalthor]

Thanks. I've already got the cap ordered, but if that doesn't solve the problem, I'll crack the motor open and see how it looks inside. I still need to figure out if the bearings are dragging, or if something else on the saw is possibly dragging. If the motor bearings are dragging, I'll need to open up the motor anyway.

I may be a little worried over nothing. The motor hasn't kicked out since that original startup, but it doesn't sound good on startup to me. I'm half tempted to video the start up and post it here to get a second set of ears to listen to it.

When the new cap comes in and I install it, I'll probably post a video, if the new cap doesn't change the way it sounds at startup.

I thought the limit switch was bad, but I took it off and opened the cover, and one of the screw terminals was really loose. After that I checked the limit switch with an ohm meter. It successfully opened and closed the circuit 30 times without a hitch. My guess is they didn't get it torqued enough at the factory, and years of vibration, got the screw loose.

 

[mksj]

One other consideration if your motor is a bit dodgy would be to replace it with a 3 phase unit and add a simple VFD which would decrease the need for belt changes. Very simple to setup as 3 wire control with momentary buttons, or replace the motor contactor with a relay/mini contactor and have it switch the VFD run low voltage input (this keeps all the other wiring/switch gear unchanged, you just disconnect the high voltage wiring to the contactor and wire the VFD directly to the motor). You could probably run the motor safely from 30-90 Hz range, maybe a bit higher but I would one needs to factor the right angle drive speed limitations. Otherwise it is a very nice bandsaw if the rest of it is in good condition. TENV/TEFC motors in that range are very reasonable as well as single phase input VFD's in the 2-3Hp range.

 

[metalmagpie]

Many many import horizontal bandsaws have had their motors replaced. Suggest you join the throng.

 

[Randalthor]

Thanks again for the additional comments. Wanted to post a follow up. Actually ended up installing the new start cap. The highest voltage one that would fit in the cap cover was 250v, so that's what I went with.

I got the oil tank cleaned out of 25 years of sludge, the oil pump started pumping oil again (someone had unhooked it, when it stopped pumping oil, rather than change the oil and clean the tank). Once I began running it with fresh oil every thing seemed to "loosen" up and the motor started right up. I think there was just so much grime from the dust (plus it had been sitting for years) it was just hard for motor to start with the belt hooked up. (That's my theory anyway).

I unhooked the motor belt to see if the motor's bearings were OK, and the motor spins very freely by hand. Likewise the blade pulley now spins very freely by hand.

I also think I figured out why the motor was so loaded sometime in the past that it melted the connection on the terminal strip in the main panel. My theory is that they had too much weight on the bow. The manual says to adjust the bow spring tension so that the bow weight is 22-24 lbs. at the lift handle. They had the bow weight at about 45 lbs at the lift handle.

The overloaded bow weight combined with no cutting fluid and all the dust clogging everything probably just pushed the saw too hard.

I plan to put a wiring diagram for the machine up on the forum, if I get time. I searched pretty hard on the internet for a wiring diagram of this saw and came up with nothing. In their manual, Jet has a "wiring diagram", but it's really not. All it is, is a drawing of the main panel with zero detail of what wires go where. Totally worthless. I could have taken a picture of the main panel, and it would have been the same thing. It took me several hours to trace all the wires, and more time to figure it out because some of the wires were unhooked. A real wiring diagram would have saved me a good bit of time.