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unisaw vibration

2855 Views 5 Replies 4 Participants Last post by  hairy
ok so many of you know i recently purchased a unisaw used and thing were all great untill 2 days ago. so im in the shop working away on a center island I've been building for a friend. time to cut some dado. so i load up my stack and start up the saw and it sounds like i have a jumbo jet in the shop. and all the stock i have on the table starts falling onto the floor i shut down the saw and start to investigate what the problem is and can find nothing of note so i try again and have stuff falling on the floor and delta flight unisaw heavy requesting clearance for take off yet again. so i come to the conclusion that my cheap shop fox stack dado is way out of balance remove it and decide not to use it and put my wood worker 2 into the saw to finish some other work. guess what now that's a jumbo jet wanting clearance to take off. i went after the usual suspects and put a new set of matched belts in this helped a bit but the vibration was still their i removed the belts and the motor seems to run smooth with no vibration. so belts back on dial indicator placed on the top pulley and their is no run out. so i dig deeper i found that the pivot pin had some play in it and that i could move the back of the motor almost 1/8 of an inch with everything bolted in so i pulled the pin and replaced it with a bolt and the movement went away. now i can run the saw with very little vibration with a single blade but if i load any stack blades at all "tried my frued box joint stack and shop fox dado" i have a jumbo jet. dose anyone have any ideas at all what is going on here.
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Could be an indication of worn out ball bearings on the arbor.

Did you check that the ball bearings on the arbor don't have any play?

To verify this you need to remove the belts and see if there is any play on it, either up-down on the belt side and the Saw side also no lateral or side to side play
their was no movement in the in the arbor i checked it both by hand and with a dial indicator. but im not sure haw freely they should turn if you spin it with no belts on it it will turn fast and free for a while should their be an resistance in the arbor.
There are a coupleof things that come to mind. First being the belts, which you addressed. Second being the arbor bearings. I woud look very carefully that one of bearings didnt spin on the arbor. I doubt that would cause the vibration you are talking about. I would try looking towards the motor next. A bad motor bearing can and will cause excessive vibraion and noise.
that was kind of my thought as well ken i just wasn't sure. i was thinking of replacing the arbor bearings just to be on the safe side because they don't look all that difficult to replace
I had a similar situation with a bench grinder. The bolts holding the electric motor to the grinder base became loose. It doesn't take much.
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