Loud Jolting Sound When Starting Tablesaw?

[orren countin]

I just got a used Delta Unisaw. The newer version with cranks on the front. 2012 mfr I think.
5hp single phase and prior owner put a big Powertech magnetic switch on it (just saying in case its the reason for the jolt)
When I start it up with a blade installed it makes a loud jolting sound for a fraction of second then a nice smooth whir.
I dont know what this saw should sound like but the jolt sound doesn’t sound right to me. Here is a video... hope it works….

https://photos.app.goo.gl/b7wePa5ohk1hNWmq5

Without a blade installed, at start up no jolting sound and just nice smooth whir.
I adjusted the belts per manual and when watching them with a blade in at start up, they expand out coincident with the jolt.
Without a blade the belts just hug the pullys, no expansion or flyout.
Do you think its just the belts need replacing or do I did I get a bummer used saw?
If its the belts would the link belts be better to use then the stock Delta part?

Any experience here?
Appreciate any help
Thanks!

[Mike Kees]

It sounds to me like shot bearings in the motor. There is definitely more noise/tingling at the fan end of your motor than it should have. Should be silent except for sound of air moving.

[Rick Potter]

My Unisaw has always started with a bang since it was new in 1993. I just assumed it was a little 'take up' on the belts. I have seen others do the same thing.

[Alex Zeller]

You can always pull the belts and turn the arbor and motor separately by hand to feel for a bad bearing. However my PM66 kind of does the same thing. It's just a very powerful motor with almost no resistance getting up to speed pretty much instantly.

[Mike Kees]

Motor start up is fine. But you need to pull the fan cover off end of motor and figure out what is up with the fan.

[orren countin]

Thank all. I did find after I removed the belts that that both pulleys were loose, jiggling back and forth. I tightened the allens and the jolting start up reduced significantly. I continue to tinker and look at the fan for its noise..

[jim sauterer]

Sure sounds like bearings unless the cooling fan is rubbing.

[Lee Schierer]

Thank all. I did find after I removed the belts that that both pulleys were loose, jiggling back and forth. I tightened the allens and the jolting start up reduced significantly. I continue to tinker and look at the fan for its noise..

Did you check the keys and key ways for damage? The loose set screws may be only part of the problem.

[orren countin]

I ran the motor unattached or no belt attached and without the fan....it was very very quiet.
I spun the arbor with a blade attached and it spun for a very long time. No movement or grinding when I turn the arbor

https://photos.app.goo.gl/rpPdE6VjGK4royED9
The delta belts look good but worn on the side and threads are showing through.
426171
I went to 2 auto stores and they could not find a replacement for it.
From what Ive found the delta belts are $71 each and I need 2. I was hoping to find a suitable replacement for a reasonable price so I can still feed my family:)
Any clues on a belt substitute?
thanks!

[orren countin]

Did you check the keys and key ways for damage? The loose set screws may be only part of the problem.

I agree. I should do that. It will always be a nagging concern. If I go to all the work to pull the pulleys to check the keys I might as well replace the bearings.

[orren countin]

Its been suggested that since the blade spins so easily (see video above) when not connected to the belts that the bearings are bad. How does that make sense?

[Rick Potter]

Check and see if one belt is a tad longer than the other. It is possible someone replaced one belt, and they have to be the same. That is quite a bit of belt slap, but it sounds just like mine has since new.

If they look like a pair, I would just tighten them up and see if you can get a drop of oil on that fan shaft, while you are checking it for being loosely fastened, or rubbing.

The motor sounds fine to me, except for that fan noise.

[William Hodge]

I would pull the table off, and make sure all the parts are bolted together, and not worn. That saw looks brand new inside. I run belts on a table saw loose, so that there is some give if something jams the blade. Those capacitor start motors can make some noise when they start. You could check the numbers on the capacitor(s), and make sure they are the right ones.

[Alex Zeller]

A new bearing with a rubber shield will actually give the bearing a little resistance. I replaced the bearings on my PM66 this past summer not because of noise but when I spun the blade with no belts on it just sounded dry. They probably still had years left in them but I decided to do them. At the same time I took the saw apart and cleaned up and adjusted everything. It's nice being able to tilt the arbor with just one finger on the hand wheel.

[orren countin]

Check and see if one belt is a tad longer than the other. It is possible someone replaced one belt, and they have to be the same. That is quite a bit of belt slap, but it sounds just like mine has since new.

If they look like a pair, I would just tighten them up and see if you can get a drop of oil on that fan shaft, while you are checking it for being loosely fastened, or rubbing.

The motor sounds fine to me, except for that fan noise.
Thanks for that. Im sure the belts are a matched pair as the stamped letters that go off the edge line up perfect when I put them side by side. Do you mean oil between the fan and the shaft?.

[Randall J Cox]

My Unisaw has always started with a jolt and kind of a bang since new, its now 23 years old and runs fine. Still starting the same way. Sure would have been nice to have a soft start feature on it...just saying. Randy

[Mark Daily]

I ran the motor unattached or no belt attached and without the fan....it was very very quiet.
I spun the arbor with a blade attached and it spun for a very long time. No movement or grinding when I turn the arbor

https://photos.app.goo.gl/rpPdE6VjGK4royED9
The delta belts look good but worn on the side and threads are showing through.
426171
I went to 2 auto stores and they could not find a replacement for it.
From what Ive found the delta belts are $71 each and I need 2. I was hoping to find a suitable replacement for a reasonable price so I can still feed my family:)
Any clues on a belt substitute?
thanks!
I would think somewhere online is a business that carries belts that auto parts stores don’t stock?

Somewhere like this:

https://www.in-lineindustries.com/products/pulleys-belts/

or:

https://www.mikestools.com/delta-table-saw-drive-belts_1843.aspx

[Lee Schierer]

Most industrial supply houses carry gates belts.

[mike stenson]

My Unisaw has always started with a jolt and kind of a bang since new, its now 23 years old and runs fine. Still starting the same way. Sure would have been nice to have a soft start feature on it...just saying. Randy

Mine's also kind of clunked since new, and is also about 20 years of doing so. Sounds a lot like the OPs ;)


https://photos.smugmug.com/photos/i-sKTcrwT/0/db06e31f/1280/i-sKTcrwT-1280.mp4

[Rick Potter]

If the belts match, I would just put them back and try to tighten them a bit more.

About the oil. Yup, just a couple drops to see if it quiets anything down. I doubt that motor needs the bearings oiled, never checked mine.

I mention this for two reasons.
1. Main reason....a bit of oil, or even WD40 on the shaft where it enters the motor (not the outer fan housing). If it quiets the 'fan' noise it is an indication the bearing is bad, and you proceed from there.

2. Secondary reason....I have a 16" Delta bandsaw that actually has a plastic plug on the end of the motor that opens to put oil in. I doubt the Unisaw has this, but ....you never know 'till you look.

Have you removed the fan cover to see if it is loose, or touching something? Could be something as simple as a loose set screw, or even a little chunk of wood that managed to get in the housing.

[Ron Magliocco]

You can try this company. I’ve never used them but I will if I need something they sell. They’re local to me and have been around a very long time.

http://rbbirge.com/?matchtype=p&network=g&device=m&keyword=rb%20birge&campaign=1745624531&adgroup=71090882551&gclid=EAIaIQobChMIxevrgorc5wIVQZyzCh1MEw7oEAAYASAA EgLjpPD_BwE

[curtis woodall]

As far as belts go, you need a fractional horsepower belt, not an automotive belt. The Gates brand makes fractional HP belts and a lot of auto parts stock them. The come in 4Lxxx, 5Lxxx, "A", and "B" series. These belts are measured by "top width" and outside circumference. 4Lxxx (the xxx designates length) and 5Lxx are standard fractional HP belts. The "A" and "B" series are a bit more industrial but can work as heavy duty replacements.

(I worked at a parts house all through Jr. and Sr. high school.....I'm 61 now and still remember)

[Jerry Bruette]

The belts are showing a little bit of wear but are still usable. The reason you can see the threads on the sides of the belt is because they're what's called a raw edge belt. They're made that way, it's not from wear.

The only way to tell if they're a matched set is by looking for some sequential numbers on the belts. They could be 156 157 158, or 078 079 080. Any combination of three sequential numbers. Both belts should have the numbers as close to each other as possible. One belt could be 156 157 158 and the other belt could be 157 158 159. That's what makes them a matched set.

I would buy the notched belts like you have if you're replacing them. They have a better wrap on the sheaves and won't take a set as easy.

[ed vitanovec]

My 5hp Grizzly Sliding Table Saw started up with a bang and so does my 3hp Shopfox, it was normal sound for motors with magnetic switch.