How hot should the motor on my bandsaw get?

[cambournepete]

I was doing quite a lot of resawing a log yesterday with my Jet JBS150 BS and noticed this odd smell, which I finally traced to the paint on the BS motor which was too hot to touch.
Is this normal?
Was I doing something wrong? The blade did stall occasionally after which I often had to manually start the blade as the BS start there whining at me.
Have I broken it?

Pete

 

[Chris Knight]

Pete,
It sounds desperate! Motors should never get too hot to touch in normal service - pleasantly warm is OK.


Do you mean it would not start without a helping hand in a no load condition after one of the stalls?

Sounds as if your blade is very blunt or something I have never stalled my Kity 613 even resawing very hard oak at full depth.

 

[Waka]

Pete

I would say that your mototr is on the way out, as Chris mentions you shold still be able to touch the motot even under full load.

You will more than likely have to change the motor.

 

[Adam]

On my jet disc and belt sander it got so hot it melted the sticker with the motor rating on it - which was stuck onto the motor. It was too hot to touch. I checked this with Jet and they said this was OK. Its well worth dropping Nick (a.l.a. Jetman) a PM just to check.

Adam

 

[CHJ]

Pete, If you are saying that the motor will not start when there is little or no load on it then it may have a starting capacitor/wiring fault.

How free is the pulley/blade setup, is this binding somewhere i.e have the guides moved or go something jambed in them trapping the blade?

 

[cambournepete]

Pete, If you are saying that the motor will not start when there is little or no load on it then it may have a starting capacitor/wiring fault.

How free is the pulley/blade setup, is this binding somewhere i.e have the guides moved or go something jambed in them trapping the blade?

Sometimes it did, sometimes it didn't. I'll have a play tonight and see how it is. I'm already on my second starter capacitor. :roll:

As for the blade being sharp - it's a new blade, but how long would people expect a dureedge blade to last when resawing hard wood? Can they be resharpened economically?

Pete

 

[Alf]

I'm already on my second starter capacitor. :roll:

Hmm, that would suggest something really not right at all, to me. But I freely admit I know nothing.

Cheers, Alf

 

[Waka]

Pete

Associated with the starter capacitor I think there is a centrifugal switch, did you change this as well.

The main reason for the motor to heat up to the temps you mentioned (very Hot) is because the saw is being overloaded. It might be worth taking the belts off and seeing if the motor turns free hand, if its stiff it could be the motor bearings. Another posibility is saw dust, have you checked that the motor is sawdust free.

Correct me if I'm wrong but don't these machines have thermal overloads to prevent the motor from overheating.

 

[CHJ]

Associated with the starter capacitor I think there is a centrifugal switch, did you change this as well.

....snip.....

Not all motors have a switch, the low cost aluminium bodied ones don't usually bother to disconnect the starter capacitor/wiring, they don't have such a high stating torque as a result just enough of a phase shift to get the rotor turning.

Pete, I would certainly look to something binding somewhere before changing the motor, even if the motor is now defective, wouldn't want to cause the same problem with a replacement.

If there is/are a shorted turn/s on the motor field windings then it will heat up whilst running on no load, can you try this. (take belt off)

 

[cambournepete]

Thanks for the suggestions - I'll have a play tonight and report back.

 

[cambournepete]

The capacitor has a bit of black stuff round the top and has leaked slightly. I took off the blade and still the BS wouldn't start. I then took off the bottom wheel, pulleys and drive belt and it did start. There was some dust around the bottom wheel bearing - which is the same axle as the drive pully, so could this have been causing the problem?

Tonight I intend to take off the bearing uint and oil it a little, although it seems quite smooth and free now.

Does this sound sensible?
Anything else I should try?
Should I leave it running freely for a while to see how warm it gets?

Cheers,

Pete

 

[Waka]

I took off the blade and still the BS wouldn't start. I then took off the bottom wheel, pulleys and drive belt and it did start.

This is showing that the motor could be ok, I'd give it an extended run under no load to check if it starts to get unusually hot.

There was some dust around the bottom wheel bearing - which is the same axle as the drive pully, so could this have been causing the problem?

It looks like you may have narrowed the problem done, have you checked the pully that the belts go to from the motor, are these free running.

Also when you start to put it back togewther again, you should be able to turn the motor with the pully and drive belts by hand.

Hope this helps

I'm not sure but I wonder if there was to much tension on the drive belts.

 

[Adam]

The capacitor has a bit of black stuff round the top and has leaked slightly.

Hasn't their been an international problem with capacitors? All industrial espionage cloak and daggers stuff about stealing a rivals formula for the electrolytic used in caps? Only they didn't get it quite right? And cars/computers have been failing a lot?

Did't someone here report it recently? Badcaps.net?

http://www.badcaps.net/ident/

Adam

 

[Jarviser]

Tonight I intend to take off the bearing uint and oil it a little, although it seems quite smooth and free now.

Does this sound sensible?
Cheers,
Pete

If I'm not too late, I have had bad experience oiling ball-bearings in bandsaws. If they have metal shields, the oil may well attract enough dust to jam the bearing solid. The code number on the bearings may have Z or ZZ at the end. If the bearings are indeed at fault you could try bearings with 2RS instead of ZZ (2 rubber seals instead of 2 shields). My Record BS250 has shielded bearings, and I have already replaced NINE jammed-up bearings in the lower blade guides in a year. I am waiting for the bandwheel ones to go. Try browsing the web for USA budget suppliers.