Bandsaw vibration - how much is normal?

[GraemeD]

I have recently completely rebuilt an old 12" MiniMax bandsaw ("Professional 32" model) which I bought in a sorry looking used state, and now find that the machine vibrates whilst it is running. The vibration seems to be coming from the top wheel.....it's not too bad, but I guess I was expecting a solid machine like this to be more or less vibration free.

I just wanted a sanity check from some knowledgeable forum members to see if my expectations are unreasonable!

This machine may not be familiar to many as it isn't the most common, but if you imagine a Startrite 301 (fabricated steel frame with cast iron table), it is quite similar. Everything has been carefully aligned and set up, and I'm using a nice new 1/2" DureEdge blade. It certainly cuts nicely, but the top of the machine visibly shakes (1 or 2mm?) in time with the wheel rotations. The cast iron wheels had been balanced during manufacture, but I tried adding small magnets to the rim at various places in case it was out.....but that only seemed to make it worse! Either my weights were too heavy, or this is not the problem.

I did change the top wheel bearings as part of the rebuild, and have a tiny inkling that one of these might have been stressed a little during installation.....having had that apart again, the rear bearing did have a touch a play in it, but nothing excessive. Would this be enough to cause my vibrations?!

Any thoughts or experiences would be very gratefully received!

Graeme
~~~~~

 

[Corset]

I had a similar problem and discovered I had a dodgy bearing and the alignment was out slightly. Also check the motor mounting as mine was incorectly attached. Finally check the weld on the bandsaw blade as this can add to the problem. I would however saw my bandsaw is at the budget end on the market so its not in the minimax league.
Owen

 

[woodbloke]

Having just read the excellent piece in F&C this month on bandsaws it appears that the main culprit for vibration is badly balanced wheels, might be worth checking them on your machine - Rob

 

[WellsWood]

Might also be worth checking the balance of the wheels, particularly the top one by the sound of it. On some machines the wheels, if cast iron, are balanced in the factory by drilling holes in the casting, but I've seen ally ones done with stick-on or clip-on weights similar to those used for car and m/cycle wheels. If you've lost a balancing weight I can imagine it would easily produce your problem.

 

[Harbo]

Have you tried removing the blade and spinning the wheel.

I think I read somewhere of somebody managing to spin one using an electric drill?

That would show up any problems with it?

Rod

 

[GraemeD]

Thanks for the input so far guys.....sounds like the consensus may be wheel balance.

The wheels are cast iron and had been balanced at time of manufacture by drilling holes in the rim.....so I can be sure they are as they were when they left the factory. However, maybe with tyre wear they are now out of balance?

As I mentioned in my original post, I did play with some small (10mm diam x 3mm thick) magnets, trying them at various points on the rim, but with no success. It seemed to make it worse or have no effect. Are these simply too weedy to fix my problem, and should I be trying more weight?

Woodbloke - F&C article sounds interesting.....was it in the June edition (ie. still in the shops)?

All the best
Graeme

 

[woodbloke]

GraemeD wrote:

Woodbloke - F&C article sounds interesting.....was it in the June edition (ie. still in the shops)?

July, so may not be in WHS yet - Rob

 

[Lee Brubaker]

Sometimes BS vibration can be caused by the drive belt. At least mine was & I switched to using a link belt which corrected the condition.

Lee

 

[Scott]

I have a P32 Graeme and it doesn't vibrate unduly so you do have a problem. I replaced the wheel bearings in mine a couple of years ago (more because of the age of the thing than out of any perceived problem). Didn't vibrate before or after the bearing change.

With the wheels being factory balanced my gut reaction is go back to the wheel bearing and check again. There is a smidge of play even in new bearings. Did it vibrate before the rebuild?

 

[GraemeD]

Thanks for all the additional input. This bandsaw has no belt....the lower wheel is directly driven by the motor.....so at least that is not the issue, but thanks for the thought, Lee.

Scott....I bought the saw in an unusable state so unfortunately I don't know if it had this issue before the rebuild. If your P32 saw doesn't vibrate, it does seem like it could be my bearing. I bought good quality ones, but I'm concerned that the rear one got damaged during installation having installed the bearings into the wheel first in a vice, and then pulling the wheel on using a bolt through the spindle. I later learned that this applies stress across the bearing, and that the rear one will have been subjected to more stress than the front one (which had less spindle length to slip on to). Having taken it all apart again last weekend, the inner one did have some play in it.

So, does your P32 not vibrate at all? Mine isn't terrible, but is certainly noticeable by eye, touch or sound. How did you install your bearings?

Is anyone with bearing knowledge able to suggest if this would cause my problems?!

Graeme

 

[9fingers]

If the bearing is damaged, then it will either feel lumpy and or have excessive play. Feel how much play there is at the edge of the wheel - should be less than 1mm roughly. With the blade removed, spin the top wheel as fast as you can and listen for any noises and vibration
Depending on the design, there might be play in the tracking adjustment. Worth a look.

Bob

 

[Scott]

Graeme

I'm at sea the moment so if you can hang on till next week I'll open mine up and remind myself what the bearing arrangement is maybe measure run out etc.

I wouldn't say there's absolutely no vibration but I'm not aware of any and it has never struck ne that it vibrates. Will try the coin-on-edge test next week for you

 

[Jake]

With a bandsaw of that quality there should be no really discernable vibration - certainly not enough to make you concerned enough to post about it! There's something wrong, that's for sure.

 

[bob_c]

I have an 18" Jet bandsaw, which vibrates badly in the top half .The table vibrates alot but stops if i hold it or lean against the table .Ive fiddled around with it ,checked the bearing etc..and cant find anything.Does a too tight belt cause vibration?? It works fine but the vibration is annoying.

 

[Digit]

Does a too tight belt cause vibration??

Can do, so can a slack one when actually cutting.

Roy.

 

[GraemeD]

The more I hear from you guys, the more I think this isn't right....and that in my case the cause of the problem is most probably my replacement bearings.

However, I think I need to have a more thorough play with the wheels before dismantling it all again, as so far all my tests have been with the blade in place, and that still leaves too many variables!

Maybe I need to try Rod's suggestion and spin the top wheel with a power drill.....it certainly doesn't feel gritty or exhibits any play when moving it by hand, but maybe at speed it will vibrate.

I did a bit of Googling and found that you can easily damage the bearings during installation if you press on the wrong ring (ie. you must press on the inner ring for installation on a shaft, and on the outer ring for installation in a housing....kind of obvious I guess). I did not do this, so potentially put stress on the bearing's insides. This can cause something called "brinneling", where the ball bearings mark the inside of the ballrace, and cause vibration. Whether this is my problem is still to be proved, but I am sensitive to the fact that I might have been a bit heavy handed when I pressed in the back bearing.

Anyway, I guess I've at least learned a new and very impressive word if nothing else!!

Graeme

 

[Digit]

Have you also re-tired the wheels?
They can cause problems as well if not centred on the rim correctly.

Roy.

 

[GraemeD]

I did not replace the tyres as part of my rebuild....they are the original ones which I think (hope!) are good enough. I fixed everything else but held off replacing the tyres as they are hard rubber bonded-on ones, and did not seem to be in too bad a shape. So unless the wear has been uneven, I'm hoping this isn't my problem!

 

[Digit]

Does it vibrate if you remove the band?

Roy.

 

[GraemeD]

A good question! I've been running it with the blade installed during all my tests.....I think I need to try and escape to the workshop for a few minutes tonight and remove the blade, and run it up. Since the vibration seems to come from the top of the machine, I'm assuming it will be fine with no blade fitted.

But we will see.....!