Worrying Bandsaw 'symptom'.

[Benchwayze]

My Startrite 351 bandsaw has sudddenly developed a 'soft-start' feature.

I used it yesterday for the first time in about a month.

When I pushed the start button the motor started to run up, but there was a small hummimg sound, and a delay before the motor picked up to speed. I've never noticed this before. The perfomance didn't seem to be affected and there was no sign of any strain on the motor, when cutting through some 3" mahogany. (With a blade that really is approaching change-time. )

The saw is well-used, and I've always done my utmost to keep the motor free of dust. (The motor is in a silly place, in my opinion.)

I suspect brushes, or maybe the capacitor. (It could just be this prolonged cold spell, biut I doubt that!)

Can anyone with electrical knowledge put me on the right track for sorting this out please?

Cheers.
John

 

[OPJ]

I'd say it could be the capacitor. I had a similar problem a few years ago with my previous planer/thicknesser. But, in my situation, it wouldn't pick up to full speed at all and needed 'a push' to get it going (otherwise, it was just buzzing).

Actually, I tried a new capacitor on mine but it didn't make a difference and I had to buy a new motor after all... We're talking cheap Chinese motors here though. Almost certainly, the one on your Startrite saw will be built much better! :wink:

 

[Benchwayze]

Thanks Olly.

The saw is still working ok, but it's niggling me.
I have the manual in a drawer somewhere, so I'll find out if they tell me the make of motor.

I contacted Bob 9fingers too, 'cos I know he's smoky on such matters.
Good job I have a spare motor sculling around... If it will fit! Although I was going to use that for my metal-lathe..

Cheers.

John

 

[9fingers]

John,

Your motor won't be the type that has brushes. It is an induction motor and has a centrifugal starting switch inside the motor, a capacitor - usually a bulge grafted onto what is otherwise a generally cylindrical motor body or perhaps tucked inside the box where the wires go in, and the starter switch/buttons that you press to start the machine.

The most likely culprit is dust inside the starter switch. With the power off open that up and clean/blow out the dust and re try.

EDIT - Now that my brain has been re-started - this first point is only likely to be valid for motors that won't run at all. Sorry

Next it might be the centrifugal switch inside the motor. Some motors have vent holes which also let in the dust. Again blow out the dust and retry.

Next remove the capacitor and wire it in series with a table lamp which MUST be fitted with a real filament lamp. Connect to the mains and the light should come on nearly if not just as bright as normal.
This possibly indicates the capacitor is a good-un. Don't leave this running for more than a few seconds.

Lastly, strip down the motor to expose the centrifugal switch which is almost always located at the non shaft end of the motor.
The switch may have got corroded contacts and clean those up with a little fine emery paper.

If the capacitor test fails then send me a photo of it with the writing showing the value, voltage and style and I can get you a new one.

Bob

 

[Benchwayze]

John,

Your motor won't be the type that has brushes. It is an induction motor and has a centrifugal starting switch inside the motor, a capacitor - usually a bulge grafted onto what is otherwise a generally cylindrical motor body or perhaps tucked inside the box where the wires go in, and the starter switch/buttons that you press to start the machine.


Bob

Ahhh! So That's why my Coronet Major has kept going on and on and on since 1971! And there was me thinking, 'I must check those brushes oneof the days!' :lol: :lol: :lol:

Cheers Bob. I'll get a photo of the bandsaw motor as a start. I will look into these matters you mention and let you know how we get on.
Many Thanks again.

John

 

[9fingers]

Correction made to my earlier post

Bob

 

[thomvic]

I had exactly the same symptoms on my SIP HD 14" bandsaw. However, the motor worked normally when I slackened the blade tension off. It turned out to be a bearing tightening up on the lower blade pulley. New bearing - problem gone.

Richard

 

[CHJ]

I had exactly the same symptoms on my SIP HD 14" bandsaw. However, the motor worked normally when I slackened the blade tension off. It turned out to be a bearing tightening up on the lower blade pulley. New bearing - problem gone.

Richard

I've had this problem with my SIP, Although in my case it manifested itself by increased noise as the bearing seized and spun in its housing. I fitted an extra thick card washer/seal in the rear bearing recess to help keep wood dust from collecting in the bearing housing.

 

[thomvic]

CHJ

A wise precaution I agree - I just bought good quality sealed bearings. However, I don't really think the problem was dust anyway. Just cheapo bearings. I had similar problems with the blade guide bearings after only a few weeks of occasional use. The replacements are still fine after 3 years of much frequent use.

[/quote]

 

[DavidE]

Hi John,
This is exactly the same sympton my bandsaw has when it is very cold. Once it has got going it is fine. Did your "soft start" feature persist?

Cheers
David

 

[Benchwayze]

Hi David...

Not any more!
I have the motor ready to put back together! :lol: :lol: :lol:

Thanks David.
Regards
John

 

[9fingers]

Sounds like you might have it sorted John
What was the problem?
Bob

 

[Benchwayze]

Hi Bob,

I couldn't really find anything that looked dogy in the motor, but a little dust. A loose loose contact in the square junction box (I think that's what it is) on the case! There was dust in the start-switch itself too, but again, I just cleaned it out and np. Slacked of the tension just a little. Motor back on and running fine. Oh and a new blade fitted! Apart from blades, good for another 20 years I hope! :lol:

Thanks for the advice everyone, and esp Bob for your time and trouble, in sorting out the specifications.
Cheers.
John

 

[DavidE]

Hi Bob,

I couldn't really find anything that looked dogy in the motor, but a little dust. A loose loose contact in the square junction box (I think that's what it is) on the case! There was dust in the start-switch itself too, but again, I just cleaned it out and np. Slacked of the tension just a little. Motor back on and running fine. Oh and a new blade fitted! Apart from blades, good for another 20 years I hope! :lol:

Thanks for the advice everyone, and esp Bob for your time and trouble, in sorting out the specifications.
Cheers.
John

Excellent news - glad you have avoided a persistent problem! David

 

[bobscarle]

I have a similar problem with my Perform lathe, slow to start, although I can give it a push to get it going. I suspect that will end up being replaced as it is not worth much and probably not worth repairing .

Bob

 

[9fingers]

Bob,

As John has shown, often the problem is a little cleaning and the problem is solved and even if it turns out to be the capacitor, less than a tenner will sort it.

Surely that is worth investigating rather than throw something away??

9fingers

 

[bobscarle]

Is that all? I was thinking it would be considerably more. definitely worth taking the motor off and stripping it down.

Bob

 

[CHJ]

...definitely worth taking the motor off and stripping it down.

Bob

Almost guaranteed you don't need to touch the motor other than to take the capacitor housing off and replace the capacitor. (Black domed cover on side of motor.)

Cut the two wires and use some small 'chocolate strip' to reconnect new capacitor.

Take capacitor and cover to local electrical factors to make sure you get one for continuous rating (run type) and of a size that will fit into the housing. If all else fails ask Axminster to supply one, £6? but postage may be as much again.

The aluminium motor fitted to the perform has no internal switches etc. to fail or get clogged with dust.

 

[Benchwayze]

No more machines for me Bob! Unless I get a slightly bigger bandsaw. A 12" wouldn't have a much bigger footprint, and there's plenty of head room in my shop. That's about the only thing I have a lot of. headroom... And before the comments come in, yes at times there is space between my ears!

If you do buy a new lathe Bob, have a good look at everything possible. Some of the time you'll be asked to pay extra just for a label and a different coloured paint-job!

If your motor is on a separate mounting, why not look in that advertising magazine they sell around these parts. Look for a firm who recondition motors. You might pick up an old British made jobbie that will be a better buy than new.
Regards

John