Bandsaw vibration - Advice?

[Dissolve]

This is a wild guess: your bottom wheel bearing is knackered, so there's quite a bit of friction to overcome when starting-up. Try it with absolutely no load on the motor. In other words either completely slacken or (better) take the drive belt off altogether. I'd expect an audible hum for a moment or so, at worst, and apart from the fan it should be pretty quiet. Compare it to another induction motor of similar size, if you can. If it's quiet, you probably have your answer.

Incidentally, If it has starter contacts you should hear these drop out with an audible click after a second or two of running, and drop back in when you cut the power (they're centrifugal and they switch in the starter coil). If the motor is small enough it may not have them fitted. Otherwise apart from the fan, it ought to be pretty quiet.

I may have explained this badly. Basically the motor sounds fine whilst running. But before switching the motor on, but with the plug switched on at the wall, the motor makes a humming noise continuously until the motor is switched on with the NVR switch.

It's not loud, but it's the sound I experienced on a previous bandsaw that had a dead capacitor, although the noise was only present when pressing the NVR switch on with that bandsaw..

Basically when it's plugged in, and then switched on at the plug type humming starts, and when the motor is started and stopped, the humming is still present afterwards.

I've also purchased new bearings! So hopefully that'll do the trick with the vibration, and I scuffed up the surface of the shaft which kept the bearings in place (Noticeable improvement to the vibration too!) The vibration improved when I slackened the belt slightly too, what could this mean?

 

[Eric The Viking]

OK: that sounds like a potentially lethal electrical fault.

The NVR switch should ISOLATE the machine. There should be nothing passing it to cause the motor to make any noise whatsoever. So as a basic minimum:

a) check the plug wiring: if you don't see Brown (live), Blue (neutral) and green/yellow (earth), be concerned.

b) If it looks like it's been tampered with (any graunched screws round the NVR or motor terminals cover, for example), be concerned.

c) With it completely disconneced, check the NVR wiring, that it's wired to either ONLY switch live (never neutral on its own), or to switch both live and neutral together.

d) test the NVR switch (carefully!) for function.

It sounds like it's wrongly wired somehow. NVR switches have solenoids in them, which would hum in normal use, except you don't hear them over the motor itself. When they're off, they shouldn't hum.

If you don't know how to test the NVR, get a competent electrician to do it for you. The basic kit required is an AVO and the knowledge to use it correctly. I'm not kidding - it sounds dangerously faulty, and I very much doubt it's the motor making the hum (based on your description above).

E.

PS: A few pictures of the machine would help, too.

 

[Dissolve]

OK: that sounds like a potentially lethal electrical fault.

The NVR switch should ISOLATE the machine. There should be nothing passing it to cause the motor to make any noise whatsoever. So as a basic minimum:

a) check the plug wiring: if you don't see Brown (live), Blue (neutral) and green/yellow (earth), be concerned.

b) If it looks like it's been tampered with (any graunched screws round the NVR or motor terminals cover, for example), be concerned.

c) With it completely disconneced, check the NVR wiring, that it's wired to either ONLY switch live (never neutral on its own), or to switch both live and neutral together.

d) test the NVR switch (carefully!) for function.

It sounds like it's wrongly wired somehow. NVR switches have solenoids in them, which would hum in normal use, except you don't hear them over the motor itself. When they're off, they shouldn't hum.

If you don't know how to test the NVR, get a competent electrician to do it for you. The basic kit required is an AVO and the knowledge to use it correctly. I'm not kidding - it sounds dangerously faulty, and I very much doubt it's the motor making the hum (based on your description above).

E.

PS: A few pictures of the machine would help, too.

Wow, thank you for taking the time to inform me of this! I've PM'd you regarding this to discuss a little further (Hope you don't mind)

On topic of the vibration (Don't worry, I won't be turning it on without checking it!! :lol: ) Does the fact the vibration gets better with the belt slackened a bit mean much?

 

[Eric The Viking]

PM sent.

On the vibration: it would hint that the wheel's bearing is the problem, but since slackening the belt also removes the transverse load on the motor's end bearing at the same time, it's hard to be 100% certain.

 

[Dissolve]

PM sent.

On the vibration: it would hint that the wheel's bearing is the problem, but since slackening the belt also removes the transverse load on the motor's end bearing at the same time, it's hard to be 100% certain.

Ah okay, I've actually just realised the codes on the bearings I pulled are 6203 RSR and the ones I ordered are 6203 2SR. According to bearing code charts RSR is single rubber shielded bearings and 2SR is double shielded . The bearing I pulled has a rubber shield on either side of it, I'm not sure if I ordered the correct type? Does 2SR mean double shielded on each side?

If it ends up vibrating even after replacing the wheel bearings, is it possible to repair/replace motor bearings?

 

[CHJ]

As long as you fit the bearings so that they have a seal on the outward facing sides to keep the dust out it doesn't really matter whether they are single or double sided sealed units as dust can't get into the centre of the wheel.

 

[Bale]

Hi Cheerup

If you are still looking for a solution to your vibration problems, can I suggest an alternative approach? I have owned and used quite a few small bandsaws, and most of them shook like a wet dog if not properly supported. Before replacing any more parts, aligning wheels and adjusting belts, unbolt the saw from its stand, sit it on a solid floor, stick a wedge under any wobbly corner and try it again.

I owned a BAS316 for many years. It came with the 4-legged stand and worked fine as long as it was sat solidly on the floor with a shim under any wobbly leg. They are not the most rigid of machines, but it served me well. My new Charnwood bandsaw arrived last month. It has a self-assembly sheet metal box type stand. I put it together, sat the whole thing on a wheeled stand and it shook like a beast. Off the wheeled stand, it's a lot better, but the box and sheet steel base are flexing and the thing still shakes. I haven't done it yet, but I know that if i throw away the supplied stand and build one out of 3x2, it will work fine.

I see from your profile you're in Portsmouth. I'm just up the road in Southampton. If you would like another pair of eyes on this, give me a shout and put the kettle on

Hope this helps.

Pete

Oh! And you need to get that electrical problem sorted pronto.