Bandsaw Squeal

[BuckeyeDennis]

By close observation with my bandsaw running and the cover off (CAUTION!), I noticed that my squeal happened when the blade momentarily jumped from running in the gap between the bearings to running on the surface of one of the bearings. I fixed it by readjusting those bearings so that the gap between the bearings is directly behind the blade and absolutely parallel with the blade. It took quite a bit of tweaking to get it right.

Gary

When I bought my bandsaw (used), it had a frozen backup bearing. I replaced them all before operating, and carefully adjusted it as you described. I don't have a lot of time on it yet, but so far have not heard a single squeal.

I think I recall recall Bill Mayo posting that he hones slight chamfers on the back edge of his bandsaw blades, to help them track in the groove between the bearings.

EDIT: Whoops, got pulled away in the middle of posting this, and see that Bill Mayo has already re-posted his honing advice.

[mountainbreeze]

I have adjusted the auto-track bearings to be perfectly aligned with the blade. The blade tracks in the groove perfectly and has no propensity to jump out of the groove. The squeal is still there. What I find odd is that the squeal stops whenever I start cutting wood. Guess I'll try replacing the bearings and see what happens.

Now I need some education on bearings. If I look up 627ZZ on the VBX website, I find that they are SHIELDED bearings and cost a mere 1.49 each. Then there is a SEALED bearing (627-2RS) that costs 5.77 each but seems like it would be better suited for the given environment. Any thoughts / recommendations?

[joshh]

IIWM I'd go with the sealed bearings.

There is some really good info here:
http://wiki.vintagemachinery.org/Ball%2 ... rimer.ashx

[billmayo]

IIWM I'd go with the sealed bearings.

There is some really good info here:
http://wiki.vintagemachinery.org/Ball%2 ... rimer.ashx

Excellant reference. I always try to use ABEC3 or higher rated bearings for replacements. The control sheave end bearing has always been a shielded bearing. This allows the aluminum dust from the sheaves and belt dust to be pushed into this bearing over time. I find that using 12 to 20 drops of oil to flush this bearing 2 or more times when lubricating the headstock each time greatly help prevent the failure of this bearing. I have not tried using a sealed bearing as a replacement (maybe too much heat at 9,000 RPM?) as I have been able to recondition most of these bearings with the excess oiling to flush out the crud from the bearing. When replacing this bearing, I find I have to machine the bearing depth in the control sheave another .08" to .09" deeper so I have material to stake the bearing to prevent it from pulling out. I repeat the oiling a few times if the control sheave is removed from the headstock by using the idler shaft (acts like a plunger) to accomplish this flushing with the oil. I find that sealed bearings do generate much more heat when operated at higher than 7500 RPM speeds.

[BuckeyeDennis]

I have adjusted the auto-track bearings to be perfectly aligned with the blade. The blade tracks in the groove perfectly and has no propensity to jump out of the groove. The squeal is still there. What I find odd is that the squeal stops whenever I start cutting wood.

Hmmm. Any chance that the back of the blade is touching the upper blade guide roller bearing when you are not cutting wood? It's supposed to clear by a fuzz (less than 1/64") when not cutting. I'm wondering if it might be rubbing the bearing ever so lightly -- enought to make a squeal, but not enough to make the bearing spin. When you feed wood into the blade, that may press the blade against the bearing with enough force to spin the bearing, thus stopping the squeal.

[JPG]

WARNING:! What follows is :eek:opinion:eek:!

Squealing is caused by stuff sliding against other stuff. When bearings squeal due to lack of lubrication, it is because parts slide against other parts and some parts get to vibrating while sliding.

Since the blade and bearing outer surface are not lubricated, one can envision the parallel here.

So what is sliding/vibrating???

The only things moving are the blade and(hopefully) the bearings outer race and balls(and hopefully the shield or seal).

The most likely(to me anyway) location of the squeal generator is the back of the blade and the outer surface of the bearing(assuming adequate lubrication internal to the bearing).

Dusty has mentioned elsewhere that lubrication of the blade back and bearings outer surface does no good at eliminating the squeal.

That just does not make sense, but I do not doubt for a picosecond(or less) that that tis the way it is.

That tells us(perhaps) the squealing will occur even when slippery is included into the mix.

I have been convinced(likey due to the lack of squealing on my two bandsaws which is also likely to be on 'borrowed' time) that the blade must be 'sliding' on the bearing outer race.

IIUC the squeal goes away when the blade is forced tightly against the bearing as when actually cutting or pulled away from the bearing(s) manually.

My 'conclusion' is that the squealing has to be created by the back of the blade skewing ever so slightly against the bearing. This may be exacerbated by wear, but again Dusty says old/new bearings makes no significant difference(if my memory me serves correctly).

Not having 'the problem' myself, I cannot suggest any way to try and narrow the cause other than a risky touch moving parts when they are squealing.

I do however think near perfect alignment of the blade to the bearings(groove if dual bearings) is mandatory to achieve near silence(no squeal).

The back of the blade must not skew against the bearing(s) be it the outside surface or the 'groove' between dual bearings.

Anyone tried minimal honing of the back of the blade? Might make it worse if a rougher surface is created.

Time will tell!;)

[dusty]

I have spent many hours trying to quiet my two bandsaws. They both have had more than a few bearing changes and have been subjected to extensive pushing and prodding here and there trying to find something, anything that wold make them quit.

The good thing is that the noise does not adversely effect cut quality. I have gotten so that it is a "noise, what noise" sort of situation.

[keakap]

Gotta admit I have not tried this, but, anyone tried jpw on the guide bearings and blade? Maybe rounding(ever so slightly) the back corners of the blade. Mine do not squeal(yet????), so I be at a disadvantage here.

Harmonics.
Maybe different on each machine, but on mine, if I run the saw and get that noise, if I push my thumb and ring finger (left hand) against the saw cover, with the thumb at an angle of 27.85 degrees higher than the finger, hand twisted to the point where the heel of the palm is just touching the surface, and my right knee bent to touch the bench tube with firm pressure, while with my right hand alternately rubbing circles on my head and scratching my as#--- Oops! Wrong invocation instructions!
What I meant to say was that I can change or stop the noise by pushing at certain places on the saw's skins. Thus "harmonics".

But reaching outside the scope of the paranormal, I think there may be something to red's query re rounding the blade backs. I get the noise differently with different blades, and I realize now that some but not all of my blades have been thru the rounding exercise, for smoother curve cutting, and next time I have the BS fired up I may try each of those blades and record any relationships re squeal vs round-heels.

Interesting. Could be a break-thru. Meantime, my -29db earmuffs will make the racket tolerable. (and I should be wearing them anaway)

[reible]

If I have time tomorrow I will get the movie camera out and make a short video of what it should sound like, ie no extra noises.

I got mine used, replaced the bearings and did a tune up. I have never heard any strange noises. No shopsmith bearings are being used see thread below for details.

I have had the saw from mid 2011, so maybe it has not run in to the noise zone as of yet.

I am running ceramic guide blocks which are not as quiet as the cool blocks that I sometimes run. The metal ones from shopsmith are no longer in the picture....

This is the link to some of what I did to my cast iron top saw

https://forum.shopsmith.com/viewtopic.php?t=8361

Lot of information for those that have not read that thread yet. And a lot of references to others posts.

Ed

[claimdude]

I upgraded my band saw earlier this year with the double bearing setup discussed here in the forum and it has not squealed since then.

Jack