Odd Unisaw vibration

[Dan Hahr]

Anyone have a problem with their Unisaw or cabinet saw vibrating under a medium to heavy load? Mine normally is fine, but if i am crosscutting 1" plus oak and try to do it a little faster than normal, the saw shudders slightly. The saw is the X5 and is about 5 years old. It did sit for a while and the belts may be set, but it runs smooth as silk otherwise.

Any suggestions would be appreciated.

Thanks, Dan

[Sonny Edmonds]

I've never had mine do that, Dan.
But mine is a Platinum edition, last year of the Platinum edition.
I've run mine buried in timbers at maximum height and smooth as a babies butt.
Maybe the belts. Have you tried changing the blade? Simple things first... ;)

[Pete Bradley]

I think Sonny's got it -- slipping belts. Might try tightening, but if they've got some years on them they're probably due. McMaster sells high quality Gates machine belts in matched sets.

Pete

[Charles Robertson]

Believe Sonny and Pete are right on. Have had my Uni at least 30+ years. One of several upgrades, (motors, fences, rollerbase, linkbelts). When it came to a third belt replacement, I went to link belts. No vibration, quieter, smoother operation. They have lasted over 15 years of almost daily use and take no set. Hope new belts solve your problem. Al

[Mike Goetzke]

Someone on another ww site recently had this problem. His was a major bearing problem but many suggested looking to make sure the pulleys were tight on the shaft (make sure the set screws are tight).

Mike

[Sonny Edmonds]

Believe Sonny and Pete are right on. Have had my Uni at least 30+ years. One of several upgrades, (motors, fences, rollerbase, linkbelts). When it came to a third belt replacement, I went to link belts. No vibration, quieter, smoother operation. They have lasted over 15 years of almost daily use and take no set. Hope new belts solve your problem. Al

I've always wondered about running link belts on a Unisaw. Now I know. :)
Now I'm wondering how they'd hold up to 5 HP. :confused:

[M Toupin]

Anyone have a problem with their Unisaw or cabinet saw vibrating under a medium to heavy load? Mine normally is fine, but if i am crosscutting 1" plus oak and try to do it a little faster than normal, the saw shudders slightly. The saw is the X5 and is about 5 years old. It did sit for a while and the belts may be set, but it runs smooth as silk otherwise.


If the problem is only when under heavy load then it's not the belts. If it were the problem would be continuous.

Check to make sure the shaft is clean and the pulley is tight. If that's ok then I'd change the bearings. They may feel ok by hand, but under load they could be acting up. How tight are your belts? the number one killer of bearings is too tight belts.

Mike

[Ron Williams]

If you replace the bearings replace the pulleys while you are at it. I did not and had to disassemble and replace the pulleys later. I know this will not make any sense to some of you, the folks at the Saw Center suggested it up front but I did not listen to their warnings and regretted it.

[Chip Lindley]

Consider that the *BLADE* may be flexing under the pressure of a heavy cut! Certain blades can take only a certain amount of feed. The gullets become full of sawdust and the blade flexes in the kerf. Try a different blade and see if the same happens. Over-tightening the arbor nut can cause deflection of the blade by a minute amount. Anything out of whack by a small amount at rest, will multiply exponentially at 4000 RPM. It's happened to me, so it could happen to you too!

As for arbitrarily replacing Unisaw pulleys, those are not hardware store items. And I doubt any machined steel pulleys would need replacing UNLESS they were loose on the shaft and allowed to wear out the bore OR the shaft. Any damage would be very evident. (Yes, replace those old aluminum/zinc? ones!!)

IF you suspect slipping belts, loosen the bolt that clamps the motor in position and allow it's full weight to hang on the three belts. Leave it for half a day, then tighten that bolt again! No belt slippage now for sure! Check all parts of the drive train for loose set screws and wear! If all else is GOOD, then it might just be your blade!

[Ron Williams]

[QUOTE=Chip Lindley;1025293]
As for arbitrarily replacing Unisaw pulleys, those are not hardware store items. And I doubt any machined steel pulleys would need replacing UNLESS they were loose on the shaft and allowed to wear out the bore OR the shaft. Any damage would be very evident. (Yes, replace those old aluminum/zinc? ones!!)


That is exactly what I thought and I did not take the advise of The Saw Center. However I was wrong and had to take everything apart and replace the pulleys

[Bob Aquino]

Anyone have a problem with their Unisaw or cabinet saw vibrating under a medium to heavy load? Mine normally is fine, but if i am crosscutting 1" plus oak and try to do it a little faster than normal, the saw shudders slightly. The saw is the X5 and is about 5 years old. It did sit for a while and the belts may be set, but it runs smooth as silk otherwise.

Any suggestions would be appreciated.

Thanks, Dan
A five year old Uni should not need bearings or belts. Possible that they are a bit loose, thats an easy fix. I would be more suspect of the blade. Is it a thin kerf type? What kind and how many teeth?

[Dan Hahr]

It's a 50 tooth combination blade, full kerf, Freud, and in decent shape. I never had this problem with my Grizzly contractor saw, and I bogged it down regularly. It would slow considerably, but never vibrate.

I just checked the belts. They look quite loose. SHould have checked them before I posted. Gotta figure out how to tighten them, and then I will let you all know if that was the problem

Thanks for your suggestions.

Dan

[Dan Hahr]

OK Tightened the belts, rotated them to cancel out the little bit of set and went at a 1" x 8" oak board. Cut through it like butter with a nickel standing behind the sled the whole time.

I was a little worried that I would tighten the belts too tight as I had to pull down pretty hard on the motor to get the belts tight. I could still push them in about 1/4 inch with light pressure and could push them all the way to the arbor bracket with heavier pressure. Is it normal to have to pull the motor down to get even pressure on the belts? They are just the standard stiff V-belts, not cogged or link.

Thanks again for the suggestions.

Dan

[Chip Lindley]

As I Mentioned earlier, letting the motor hang on the belts for a time will help them stretch equally. THEN tighten the clamp bolt. These are short belts and cold weather may stiffen them, so that difficulty occurs in tightening. Unisaw motors are pretty hefty. Let the Motor do the work for you!