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I don't think there is an answer to this problem.

3K views 42 replies 19 participants last post by  Finn 
#1 · (Edited by Moderator)
I have a Delta contractors saw that I have had for a few years now and it does what I want it to do. But the motor vibrates like crazy. So much so that it has even fallen off. I know that these saws are made to take the motor off for easy transport. I have taken the motor off and reinstalled it a dozen times aligned the pulleys per the manual but it still vibrates like crazy. I now have to put a stick under the motor to stabilize it while not making the belt too lose. Does anyone have one of these saws and if so did you have the same problem and did you fix it?
Thanks
 
#3 ·
I did and put a new belt on it. Since the pulleys are so small in dia. they get a set that can cause bad vibration. I replaced mine with "power twist link belts" from Rockler. Runs very smooth now. My saw is a 12" contractor saw about 30 years old. I hope this works for you.
 
#4 ·
Madts,
I have changed belts including a power link It didn't work.
Howie,
Lake Mead is close but I can't afford a new saw, otherwise this one would bo on CL or be sold as a boat anchor.
 
#6 ·
I have a friend that owns this saw and it vibrated badly. We checked it out and it was the belt sheave. I don't remember which one (motor or arbor) but I think he changed both of them and got a new belt while he was there. Just the regular V-belt. It is smooth today. I would look there then I would check for a bent shaft in the motor.
 
#7 ·
All good suggestions, thanks. The bearings seem fine and I can't detect any bend in the shaft, although I don't have a dial indicator to be sure. The strange this is that with just a little bit of support under the motor it runs smooth and quiet but when the motor hangs free it shakes. I'm thinking of removing the spring loaded mounting pins and just bolt the motor the mounting support to see if that clams thid thing down.
 
#10 · (Edited by Moderator)
Pulleys themselves may be out of balance. Perhaps the tension spring is a bit loose or soft…

Shaft can be checked with a simple jig to hold a small wire or nail up to the shaft as it spins - will give you some idea. The amount isn't really important - just that fact that it may be bent.
 
#12 · (Edited by Moderator)
Here's what I did today. Took the belt off and fired it up. The motor ran smooth. Put the belt back on and removed the blade and there was a slight vibration but it is livable. Now I'm saying to myself, What the hey. I put the blade back on and the motor jumps all over the place. OK, I got a bent blade. Nope the blade is flat and true. I use the Freud blades and this is about the 10th one I have had on this saw in the past 5 years and I have always had this problem. So, I tried another blade of a different make, same problem. I put a full kerf blade on it that I check for flatness and the motor still jumps. The saw is the Delta 36-979 with the single pully on the arbo rand the nut is tight. I'm really at a lose here.
 
#16 · (Edited by Moderator)
It's very possible that all 13 blades I have either used or just tried are a little off. That and arbor being slightly out of round would cause the motor to jump around. I have used Freud, Delta, DeWalt and Forest over the years but I have always had this problem. When I say slight vibration with no blade I mean you feel the vib. but you can barely see it. I can live with that. After all it is a contrator saw I don't expect perfection. I agree with cr1, what else could it be but the blade? I'm thinking of removing the spring loaded pins that hold the motor on and bolting the motor to trunoin. If that doesn't work then I'll just keep supporting the motor with a stick.
 
#17 ·
That's odd, I have the same saw and haven't had any issues yet. I use a power twist link belt. I get a tiny bit of vibration when it shuts off.

It certainly wouldn't hurt to bolt the motor in place; just leave a bit of slack when tightening the nuts down. Also make sure to get the biggest bolts (diameter) that will fit, and don't settle for hardware store junk. I'd get the bolts from mcmaster carr. They have strength ratings listed so you can pick bolts that won't bend.
 
#18 ·
I doubt it's the blade. I run Freud blades almost exclusively, and I've never had an issue with any of them (which, by the way, is more than I can say for Tenryu). Seems unlikely that you would get 13 bad blades in a row and I'd get 20 or 30 with no issues.

If the blade arbor was slightly bent, you would get slight vibration with no blade … slight because the arbor is fairly light and small diameter. When you add a blade to the arbor, you're adding a fair bit of weight and a bunch of diameter which means the vibration would increase exponentially.

My vote is a problem with the arbor.
 
#19 ·
I'm agreeing with Peter. I don't see how it's the blade. I've used some old cheap blades before to rough cut lumber that I knew to have some nails in it and although it wobbled a bit, the vibration was limited to the blade itself and was never enough to cause the motor to actually fall off. If the motor runs vibration free and you've tried different belts then it seems like there is some problem with the arbor. And like he said, once you put a blade on it the vibration is going to be greatly increased.
 
#20 ·
Have you thought about the arbor being under size where the blade fits? This would allow the blade to drop down a few thousandths, then you tighten the nut and lock it in that position. Now when the blade turns it is not centered and it causes this vibration.

Clamp a straight edge to the table where the teeth touch the straight edge. Turn the blade slowly and see if it moves away or cuts into the straight edge then you would know the arbor is under size. ?? or bent….?
 
#21 ·
cr1, In my last reply I did mention that this has been a problem since day one.
Grandpa, I did as you suggested. I layed a flat metal rule on the saw and raised the blade to where it just barely touches the rule and spun the blade by hand. Its' been confirmed, the arbor is either bent or miss-shapen. I'll try shiming the blade out a little and see if that makes a difference.
Thanks everyone.
 
#25 ·
There was another LJ that had a problem with his stacked dado set. He finally found an undercut at the end of the threads where the arbor was smaller. I think he built it up with JB Weld and dressed it down. I think his chippers were higher than the blade on the side and the dado wasn't flat in the bottom. This is somewhat like your problem.
 
#26 ·
http://www.ereplacementparts.com/
Looks like parts are available and cheap too. If I were to replace the arbor shaft I would replace the bearings as well. I have replaced several sets of bearings on several of the older Delta Model 10 contractors saws and they are pretty simple and straight forward. The design and parts break down for your saw is similar. I use aftermarket bearings that are much cheaper and more available than the factory ones.
 
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