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Help my bandsaw has died!

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George_N

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My old bandsaw has packed in. It is an old cast iron Wilmac 12" bench top model. I was re-sawing some fairly wet oak and it bogged down, blew the fuse and now it won't run. The motor hums but doesn't turn (1/2 hp single phase). There was no burning smell, sparks, flames or anything. I'm hoping that some of the electric motor experts on here might be able to advise me on how to work out what's happened.
 

George_N

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Yes it turns freely. The motor is direct drive attached to the bottom wheel so a direct motor swap may be difficult.
 

9fingers

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Did someone call??
Hi George
Could be a couple of things especially as the failure was associated with overload. The humming is a good sign though!

Take of the blade, and switch on the motor and spin the driven wheel. It should run up to speed.
Switch off the motor, allow to come to a halt.
Switch back on and this time spin the wheel in the opposite direction. It should also run in that direction.

Report back with your results please.

Bob

PS can you post some sharp focus photos of the motor plate (not the bandsaw plate) and a general shot of the motor please.
If you can't post here then email them to motors@minchin.org.uk

Thanks
 

9fingers

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There is a good chance it will have one of the old 'AC electrolytics' on it and that might have failed due to the bogging down. They can only stand AC for a very short period of time.
I'm hoping that is the problem otherwise it could be the starter contacts or worse still the start winding.
The good sign is that it does not smell or has let the smoke out, but the nagging doubt is that it is not often that a 1/2hp motor will blow a 13amp fuse but maybe it had a smaller fuse fitted?

Bob
 

George_N

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Thanks for the replies guys (especially Bob). Sorry I've not been on-line for a couple of days...busy with other things.
I did try spinning the bottom wheel with the power on and nothing happened. I did have the blade on though, so I'll take it off and follow your advice and report back. I'll also do a couple of photos and work ouy how to post them. It may take me a few days though until I can get a look at it in daylight.
By the way, the fuse that blew was a 15 amp (old fuse wire type) in the house fuse box, not the 13 amp one in the plug.
 

9fingers

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15 amp fuse box fuse on a 13amp ring is unusual but one or the other was possibly stopped the worst of the smoke escaping.

If you can't sort out the photo posting, just send them to me and I'll host them for you.

Bob
 

George_N

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Bob,
The electricity to the workshop (garage) is a straight connection via armoured cable to an isolator switch in the garage. From there the sockets are just daisy chained (something else I need to sort out). The bandsaw was the only thing running at the time, even the lights were off.
 

George_N

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Hi guys, it's been a few days since I started this thread and I've only just got back into my workshop today. Bob, you were spot-on, without a blade installed the motor will run if I spin the bottom wheel (in either direction). I have taken a few photos of the saw, the motor, motor plate and motor mount. Now that I know that the motor isn't burnt out the question is...is there an easy fix for this somewhat ancient baby of mine? Look forward to your replies...if anyone is still following this.










 

9fingers

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Hi George,

Is there a capacitor anywhere to be seen? either a large bulge on the side of the motor not seen in the photo or at the end of the lead?

That is one very old motor! If there is a capacitor then that is the most likely fault and is cheaply replaced.

If there is no capacitor then there should be an internal centrifugal switch that switches out the starter winding once the motor is up to speed. Either this, or the starter winding is faulty. Opening up the motor to investigate needs to be done with extreme caution on such an old motor as the internal insulation will have hardened and can easily crack. Bring the motor indoors and get it thoroughly warm before even attempting dismantling. Take photos and or make notes of all the wiring and what goes where. There will be no chance of getting any replacement parts to take it steady and don't use brute force.
There is only a 50-50 chance of recovery anyway so the answer could well be a new motor and related mechanical modifications to get it to fit. That said it looks a nice little saw and worth some TLC and the result is likely to be much better than a modern equivalent.

Good Luck

Bob
 

George_N

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Other than where the cable enters the motor there are no "bulges". As you can see in photo 4, there is a plate screwed on to a small bulge on the end of the motor. No idea whether that might house a capacitor or not but it looks too small compared with the capacitors I've seen on more modern motors. As you point out, it is a very old motor and I'm reluctant to start dismantling without knowing what I'm doing (though that doesn't usually stop me).
In the time I've had the saw, the motor has always started slowly and gradually come up to speed (10 seconds or so), might that mean that there is no capacitor to boost the start, or is that just a feature of old motors?
 

9fingers

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Hi George,

That plate will just be covering the connections - as you say too small for a capacitor. Older motors did not always have a capacitor as suitable ones were a bit of a rarity & expensive in the days of that motor.

10 sec start up time really indicates that it has been going downhill for sometime, could have been poor contacts in the switch that have now expired or the start winding having been overloaded for some time has now burnt out.
Nothing to lose by opening it up really - it is no good as it stands is it? The more care you take the greater the chance of getting a positive result.
If you go down the route of a replacement motor, you can either remove the old one completely and solve the ensuing mechanical problems to adapt to a new one or you can keep the motor body and shaft intact and mount a new motor off to the side with a extra belt drive to the old shaft.
You are too far away for me to provide anything other than written help but if you enlist the help of a local model engineer or other mechanical dabbler, you should get a result.

You are unlikely to find a modern small machine of similar quality for the price of a new motor so I would say it is worth doing - just depends on your enthusiasm for the project.

Good Luck

Bob
 

Digit

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Some of those old Hoover motors had a start relay Bob rather than a capacitor, they were much smaller than the equivalent capacitor and I'm wondering if there might be one in the casing. The end cover seems rather deep.

Roy.
 

9fingers

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Thanks for the tip.
Like the ones in fridge compressors Roy?
I've used a number of Hoover motors but not one that old.

Come to think of it my tumble drier (creda) has a current operated starter relay and no capacitor mainly because in normal use the motor is reversing every few minutes to modify the tumbling effect.

Bob
 

Digit

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Early TDs didn't reverse Bob, they simply tangled trouser legs into unusual shapes! That motor must over 50yrs old, when, as you pointed out, a 32mic capacitor would have been nearly as big as the motor, and explosively dangerous!

Roy.
 

9fingers

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Digit":zqgnmvqi said:
Early TDs didn't reverse Bob, they simply tangled trouser legs into unusual shapes! That motor must over 50yrs old, when, as you pointed out, a 32mic capacitor would have been nearly as big as the motor, and explosively dangerous!

Roy.
We must have bought this TD at least 30 years ago but I think the reversing had been around a while then but the 'new' thing was a dryness sensor in the drum. The whole machine still works well but I did have to put a new belt on last year.
Not too bad I guess.

Back to the bandsaw - I'm not sure if the OP is going to open the motor and let us see more or not.

We need a Scottish motor man really. You could do the Welsh ones, I'll cover the south coast etc

Cheers

Bob
 

Digit

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Cheers! BTW, it is a brake, of sorts, slows the motor ok, but it still stops under 10 secs without it. Mind you Bob, I still think you can do a lot of harm in a lot less than 10 seconds!

Roy.
 

George_N

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There is definitely no brake. when the saw was running it would take a lot longer than 10s to come to a stop. If I can get the motor off I'll take photos of the dismantling and post them here. It might take me a while to get round to it so don't hold your breath. If it needs a new motor I don't know if I do have the time or the enthusiasm for the engineering, as I wouldn't know where to start. It is a nice and very solid wee saw, though. Thanks for all the helpful posts.
 
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