band saw vibration - Woodworking Talk - Woodworkers Forum
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post #1 of 14 Old 09-15-2019, 09:31 PM Thread Starter
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band saw vibration

I bought this vintage 1966 general 490 bandsaw last month and gave it some much needed maintenance. I changed the tires, the wheels and guides bearings and bought 2 new blades. I've still waiting for my link belt to arrive but so far the issue is the upper wheel. Both blades move back and forth from the thrust bearing and I believe it's caused by the upper wheel vibration. When I turn on the saw and place my finger on the side of the wheel, I can see and feel the wheel oscillating, like an untrued bike wheel. Any help with that ?
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post #2 of 14 Old 09-15-2019, 10:42 PM
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Photos would help. If you shoot video it should be widescreen, btw.

I always chase vibration in steps. Take the belt off the motor and make sure it's running smoothly, put the belt on and make sure the bottom wheel is running smoothly, then make sure your blade is completely flat when the back side is laid on a known flat surface, etc.

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post #3 of 14 Old 09-16-2019, 01:09 AM
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Assuming the wheel is cast (either alloy or iron) and you have the blade tensioned properly, then about all you can do is replace the wheel bearings.
They are very cheap and easy to do.

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post #4 of 14 Old 09-16-2019, 04:18 AM
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blade issues?

Quote:
Originally Posted by charlo489 View Post
I bought this vintage 1966 general 490 bandsaw last month and gave it some much needed maintenance. I changed the tires, the wheels and guides bearings and bought 2 new blades. I've still waiting for my link belt to arrive but so far the issue is the upper wheel. Both blades move back and forth from the thrust bearing and I believe it's caused by the upper wheel vibration. When I turn on the saw and place my finger on the side of the wheel, I can see and feel the wheel oscillating, like an untrued bike wheel. Any help with that ?

Blade movement is not necessarily "vibration". David suggested laying the blade backside down on a flat surface to see if the welds are correct. If you still have the original blade test it out on the machine to see if it also meanders back and forth. What brand of blades did you get new? I would also look at the upper wheel while it's running to see if there is any movement at the bearing hub. If the wheel is oscillating as you say, it could be bent? Or it could be a bad bearing, but typically that would cause a knocking/ticking noise. If the wheel was removed when you did the upgrades, maybe a shim was left out or the nut is not sufficiently tighten down? Or a shim or washer was put in the wrong location? Changing the tire can cause the issue you have also. They must be installed correctly. You Tube shows you how.
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post #5 of 14 Old 09-16-2019, 07:36 AM Thread Starter
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Yes I did check both blades on a flat surface, they're good. As I said, it's not the bearings as I've changed them all last week with good quality japanese stuff. I did everything step by step, belt off, belt on, lower wheel has no vibration.Even when I spin the upper wheel without the blade, I can still feel the slight side to side wobble of the wheel. I also installed the tires properly and streched them out once installed on the rim. There was no shims or whatsoever in the upper wheel assembly. It's been doing that since day one, before I upgraded everything. So it's clearly not the new blades.

One thing I noticed is that one of the upper wheel bearing is quite loose in the wheel bore but the other one is a super nice fit. I posted some links to a few videos I made. The wheel movement in the second video is with no blade tension. With proper tension, the wheel has less play but still I'm not sure if that's normal. All the movement you see in the second video is coming from the bearing play, not the tilting mechanism




Last edited by charlo489; 09-16-2019 at 08:44 AM.
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post #6 of 14 Old 09-16-2019, 08:15 AM
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Ah Ha .....

Tight on the shaft, but loose inside the wheel! The bearings may be slightly undersize on the O.D. .... I donno?


That would certainly cause a wandering, wobbling issue.
Can you accurately measure the new VS the old bearing outside diameters?
How you can make them fit better is a machine shop question, but you can't really do anything with the bearings themselves, only deal with the wheel. A few ideas come to mind:
A version of removable Loctite may take up any difference.
Dimpling the area around the recess with a center punch may "upset" enough material to make them snug.

If you have to remove the wheels and have a machine shop sleeve them, that will be expen$$ive.
A cheaper approach would be a different brand of bearings, but use an OD the same as the old ones.


Good Luck to you on this issue!
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post #7 of 14 Old 09-16-2019, 08:50 AM Thread Starter
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Well the other bearing fits perfectly in the bore so I do have the proper bearings. I threw away the old ones but anyway the external bearing was still loose in the bore. Can you see the videos ? My links doesn't seem to be working
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post #8 of 14 Old 09-16-2019, 09:22 AM
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No videos or links. Are they on YouTube? If so just copy the URL and paste it into the message window.

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post #9 of 14 Old 09-16-2019, 09:36 AM
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I saw the videos. Like @woodnthings, I saw the loose fit of the bearing inside the wheel. I am no expert, but it looks like a good place to start. Bearings should be snug.
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post #10 of 14 Old 09-16-2019, 12:34 PM
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wrong bearings. measure the id of the wheel, and the od of the shaft, or bring them both to a bearing dealer - they will fix you up!

you typically have to tap the bearings into the wheel with a large socket or piece of pipe (size of the outer race). never tap on the inner race when inserting into the wheel.
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post #11 of 14 Old 09-16-2019, 05:48 PM
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Totally the wrong size bearings ....

Tim is correct. Go back to my previous post. Can you accurately measure the internal diameter of the bearing recess on the wheel?
Accuracy to 0.001 " Measure the shaft if there is any doubt as to it's diameter. Take those measurements to a bearing supply shop OR find accurate replacements online. DONE!
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post #12 of 14 Old 09-16-2019, 07:24 PM Thread Starter
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Sorry, maybe it wasn't clear but the bearings are the right ones since the other side of the wheel is all good, the bearing on the good side needs to be pressed in and it does not move. The bore on the other side of the wheel probably got enlarged by a seized bearing that the previous owner neglected to repair. So the hole is slightly oversized compared to the other side. I did check the parts list and diagram and I have the right bearing, standard 6202. The old ones that I removed were also 6202's.

I went to an industrial bearing shop today and we came to the conclusion that a larger OD bearing is the only solution to properly repair the wheel so I took it to a machinist with a new and larger bearing (42mm instead of the original 35mm), should cost me around 30$ and hopefully he won't screw it up, otherwise my saw will be ruined, no more spare parts from that brand.
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post #13 of 14 Old 09-17-2019, 10:36 AM
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Once you get it repaired it should last you until you are gone from this earth.

Don in Murfreesboro, TN.
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post #14 of 14 Old 09-17-2019, 12:35 PM Thread Starter
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All right, problem solved, I've had the bore enlarged to fit a bigger bearing, 30$ of repairs not too bad. Now the blade is perfectly still !
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