Band saw problems

[pommyphil]

I have a 6year old Hafco 16" bandsaw (MJ344) and the electrics are playing up. It would start and run for a few revs then trip the shed cutout. then came good for a couple of cuts then same again.

Now I just get a part rev and it cuts out.I've bypassed the door safety switches, taken the blade off so no load, blown out and cleaned the main switch and the little box on top of the motor ( capacitor ? )

and tried different power points, all to no avail. Is there anything else I can check before I go in search of a 'leco ? Thanks in advance (and hope) Phil.

[malb]

Is it tripping an earth leakage detector unit (safety switch) or a normal circuit breaker?

If a safety switch, there is definitely a leakage path to earth which could be a damaged or burnt winding in the motor, a chaffed wire contacting something that is earthed, or something similar that needs someone who knows their way around electricity to diagnose fully.

If a normal circuit breaker, is anything else operating on that circuit that didn't use to be, increasing the current through the breaker. If not the motor is drawing excess current, possibly dust compaction between the rotating and stationary components of the motor, faulty bearings, the capacitor that you blew out, the contacts on the centrifugal switch burnt and not making good contact when they close to start the motor, or a burnt winding.

With the blade off, try rotating the bottom wheel, if it rotates freely, then it will be driving the motor probably 3 times faster, which should eliminate the motor bearings and the motor being bound up with compacted dust. Beyond that, you are starting to get into the domain of the guy who knows his way around electricity and has an appropriate kit of meters etc.

Chinese motors have a reputation for short lived capacitors, and sourcing and replacing the capacitor with something intended to be durable under Aussie conditions may well solve the problem for you, but I don't advise a DIY attempt unless you know what you are looking for/at all along the way.

[code4pay]

Have you tried it on a completely different circuit. I had an issue with my table saw tripping the breaker. Ended up being a faulty breaker even though the bandsaw and all my other tools never made it go off.

[powderpost]

Phil, I would urge you to get a sparkie to check things out, may cost a few dollars, but could be cheaper than burning down the shed and it's contents. If you talk to the electrician, you may learn what to do next time??

Jim

[pommyphil]

Thanks Malb Yes it's the safety switch on the shed that trips.Thanks Code4pay, good idea but it didn't help. All the wireing looks perfect so it is probably the motor. Living in a small country town a good leco must travel and could cost $200 to "Tut,tut" and mumble about rewinds, a few more hundred and a few more weeks wait. I can get an identical motor for $200 brand new with warranty delivered on Friday, so I'll take the chance it is the motor and order a new one.
On the subject of bandsaws, 5 years ago I bought a TCT bandsaw blade from Henry Bro ( 3m about $120) and it's still going strong after lots of work, no good for tight curves but always sharp. Money well spent.

Thanks to everyone Cheers Phil

[Yanis]

Sounds suspiciously like a shorted turn due to insulation breakdown. The breakdown can have numerous causes including rubbing, overheating, contamination on the wiring. The breakdown and shorted turn results in a current overload which in turn trips the breaker.

If you take the motor apart then you should see some discolouration on the winding. If this is the case then you are up for a new motor.

John

PS it also may be a shorted capacitor. Take the capacitor(s) out, make sure they are discharged by shorting the terminals, then use a multimeter on the ohms scale and if it reads 0 then you have a dud cap.

[pommyphil]

Thanks John I've ordered a new motor so that should fix it. The old capacitor seems to be wired in. a couple of wires just vanish into the guts of the motor.

I'm pushed for time as I've just been given a ute load of 3-400mm dia green Mulberry that I have to break down. I'll chuck in the new motor and cross my fingers. :) Phil.

[pommyphil]

OK My new motor is on the courier so I pulled the old one apart. The "sealed" motor contained a cup full of fine wood dust and a stuffed front bearing.

The picture is after I blew out the gunk. Looks like a new bearing and it would probably run but it's 10 yr old and abused so I'm happy with a new one. 391265