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Bandsaw won't start. Help me out of idiocy please

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Bandsaw won't start. Help me out of idiocy please

Postby AJB Temple » 19 Jul 2021, 21:35

Bandsaw is Jet JWSX 16". Bought new by me and is about 5 years old.

Resawing some 4" oak today to make some joist mouldings (pitch levellers and decorative). Blade (Tuffsaws) went bang. Not unexpected as it is well used and I had a feeling.... Did not break at the weld though.

I tried to stop the saw but stop button seemed to do nothing at first, though this may just have been the racket from the freewheeling top wheel . This may be relevant - it has been a bit stiff of late. Cleaned saw and replaced blade with 3/4" M42 Starrett. Reset all guides, tensioned correctly (saw will handle up to 1" and is shipped with a 3/4"), wheels turned by hand freely and blade seated on (undamaged) tyres properly.

Saw fails to start. No hum. Nothing. Capacitor mounted on top of motor feels warm through plastic casing and motor is a bit warm. Had been using saw for an hour or so, but not pushing it. Later check: No obvious external signs of damage to capactor when pulled fro plastic case.

Checked circuit breaker, fuse, both fine. Other machines run fine from same socket. Pulled out the start stop switch and cleaned off dust. Connections all fine. Replaced.

Checked manual on-line as I thought there was a cut off overload switch. Can see no reference to one in the manual (though there is for smaller machines) and can find none on the machine.

Checked that the case closed cut out switch is not disengaged (the case pushes a toggle in when closed to complete the circuit. Would be easy to override but have not done so).

So guys? Is there something I am missing? Not got any electrical test gear out yet as this happened at 8pm.

Anything obvious that I am oblivious to?

Thanks. Adrian
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Re: Bandsaw won't start. Help me out of idiocy please

Postby Trevanion » 19 Jul 2021, 21:51

Does it have door electric interlocks? Maybe a bit of dust has gotten into one of those and it isn't making the connection properly to the switch and requires a blow-out.
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Re: Bandsaw won't start. Help me out of idiocy please

Postby AJB Temple » 19 Jul 2021, 21:57

Yes, it does. I will strip them out tomorrow, blow it all out with compressed air and if necessary by-pass the interlock switch. It is very odd for a blade break to make the saw inoperable. I use cyclone extraction normally (though not on this occasion as it happens), and saw is pretty clean.

Bottom guides were not brilliantly adjusted. But blade was not hot.
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Re: Bandsaw won't start. Help me out of idiocy please

Postby Robert » 19 Jul 2021, 22:27

If the mechanical bang caused it to lose power then the most likely culprit is dislodged dust stopping a switch or NVR relay connection. Compressed air gun and more banging then check for life before resorting to proper fault finding? .... which is more or less what you said if I'd read your last reply properly :)
Last edited by Robert on 19 Jul 2021, 22:29, edited 2 times in total.
Reason: D'oh
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Re: Bandsaw won't start. Help me out of idiocy please

Postby AJB Temple » 19 Jul 2021, 22:52

Yes, pretty much Robert. I will blast it all out. I hope it is just dirt.
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Re: Bandsaw won't start. Help me out of idiocy please

Postby Cabinetman » 20 Jul 2021, 02:20

I’m not an expert at all, but I have seen overload protection built-into some stop start switches.
Hope it’s an easy fix. Ian
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Re: Bandsaw won't start. Help me out of idiocy please

Postby sunnybob » 20 Jul 2021, 06:00

The bang would have been the blade snapping. The big iron top wheel has no brake and would have taken a long time to come to a stop, even with the remains of the lade flapping about on it.
Extremely unlikely to be anything except the door switches not closing properly.
Worth looking closely at the adjustment slots on the switch mountings, if the screws are loose it would only take a small movement to stop the contacts meeting when the door(s) close.
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Re: Bandsaw won't start. Help me out of idiocy please

Postby AJB Temple » 24 Jul 2021, 18:13

It was the door safety cut out. This is a spring loaded push pin switch, operated by a cam fixed to the door hinge pin. The pin needs to be fully out to operate. Everything was clean but the cam, which has a flat face, has suddenly stopped letting the pin out far enough. Cam removed and I will file the flat face down a bit when I get a moment. Saw working fine.
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Re: Bandsaw won't start. Help me out of idiocy please

Postby Philly » 24 Jul 2021, 19:51

Not wanting to sound silly but have you checked the fuse and circuit breaker? Could be the instant lack of load caused it to go pop? Worth a quick check?
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Re: Bandsaw won't start. Help me out of idiocy please

Postby AJB Temple » 24 Jul 2021, 21:02

Yes Philly, if you read my original post they were checked. I have a sub consumer unit in my workshop. It was the door switch as per my post above. I suspect when the blade snapped it knocked the switch out of true very slightly.
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Re: Bandsaw won't start. Help me out of idiocy please

Postby Philly » 25 Jul 2021, 11:54

AJB Temple wrote:Yes Philly, if you read my original post they were checked. I have a sub consumer unit in my workshop. It was the door switch as per my post above. I suspect when the blade snapped it knocked the switch out of true very slightly.

Ahh..apologies, glad you sorted it. Nothing worse than machines not working.
All the best
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Re: Bandsaw won't start. Help me out of idiocy please

Postby Trevanion » 25 Jul 2021, 12:08

It's always the door interlocks!
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