Help with Saw Bearings

[Kurt Wyberanec]

Hello all....I have a JET 3hp Xacta cabinet saw, about 2003 service and I need a bit of help. My saw used to run nearly dead quiet and very low vibration. I've noticed over the last year or so that it is getting louder and more vibration. My thought is that a bearing is going somewhere or maybe a belt flat spot or something. I don't have a lot of experience working on or diagnosing motors, and I can't afford for my saw to be down to take it out for service so I need to have a clear idea of what is wrong before I could do so. I am planning on upgrading this year (that will be another post soon) but even if I order now I probably wouldn't see it for some time.

My question is how can I track down this noise and tell which bearing or component it might be coming from. I obviously can't fiddle in there while the saw is running so what would I need to take apart to be able to find it with the motor turned off and how?

The saw does not appear to be losing any power or having any problems cutting so it doesn't seem to be impacting performance at this point, with the exception of vibration.

Any thoughts or advice would be most appreciated. Thanks!

[Alex Zeller]

On my PM66 I could tell the bearings were about to go after I removed the belts. When I spun the blade you could feel they were dry. They didn't make any noise though. A good bearing has a little bit of resistance to it. Both the seals and the grease inside it resist the bearing turning. It's not much and it feels smooth. My bearings had no resistance and I could feel a slight vibration. Unfortunately it wasn't until I had them out that I could tell much easier. 19 years of usage could have your bearings ready for replacement. Most likely you can buy replacement bearings for a fraction of the cost of "Jet" brand bearings. I personally like Timken bearings but there's plenty of great brands. I'm not familiar with how to replace them on your Jet saw. On the PM66 it's not a hard job but I have a hydraulic press that made it easy.

[John TenEyck]

I would first check to make sure the pulleys are tight on their respective shafts. If so, then I'd remove the belt(s) and just run the motor. If you hear vibration then that's the source of your problem, either a bearing or maybe the motor is loose on its mounting plate/cradle. If not, while the belts are off, turn the arbor by hand and listen and feel for any noise, hesitation, anything other than completely smooth rotation. Also, try tipping the sawblade left/right, rotate a little, repeat a few times, again looking/listening for anything unusual. Check that the trunnion is firmly bolted to the cabinet or underside of the table, whichever the case may be with that saw. If you hear or see nothing, anywhere, I'd replace the belts and try it again under power.

John

[Kurt Wyberanec]

I would first check to make sure the pulleys are tight on their respective shafts. If so, then I'd remove the belt(s) and just run the motor. If you hear vibration then that's the source of your problem, either a bearing or maybe the motor is loose on its mounting plate/cradle. If not, while the belts are off, turn the arbor by hand and listen and feel for any noise, hesitation, anything other than completely smooth rotation. Also, try tipping the sawblade left/right, rotate a little, repeat a few times, again looking/listening for anything unusual. Check that the trunnion is firmly bolted to the cabinet or underside of the table, whichever the case may be with that saw. If you hear or see nothing, anywhere, I'd replace the belts and try it again under power.

John

Thanks guys, I was trying to think how to isolate the parts and it sounds like taking the belts off would be able to eliminate the bearings on the arbor. Is there any risk to running the motor without the belts attached? I know in some case they're designed to have load and running with no load can damage?

In respect to making sure all mountings are secure, totally makes sense...downside is the cramped confines of getting in there to try and check :eek:

Does anyone think that the belts themselves could at all be the issue? They appear to have the usual tension on them.

Overall it's been a very good machine to me with little headache.

[John TenEyck]

You will not hurt the motor by running it w/o the belts. You hurt an electric motor running it with too high an amp draw; w/o the belts it will draw the minimum possible for that motor.

Yes, the belts could be the problem. Frayed, partially broken, a missing chunk, or a permanent set could all cause vibration. Easy enough to check.

John

[Colin Busby]

Heat can be another telltale for bad bearings. Run the saw for 5 or 10 min, then turn it off, unplug/disconnect, and feel around. Or if you are lucky and have an FLIR camera just use that. Less work than taking the belts off, but ultimately that is what you will end up doing to confirm. Spinning the motor shaft and the arbor by hand once the pulleys are off should give you the answer.

[Robert Engel]

If it’s that old it’s very likely arbor bearings.

I had the same saw (2001). It’s a bit if a job you have to remove the top. That could e tail removing the wings unless you have some hefty help.

Two things I learned, one VERY important.

1. The retaining nut (other side of arbor plate) is LEFT HAND THREAD on a left tilt machine.

2. You have to be careful about realigning top or the ZCI will not line up exactly. I suggest putting a blade on while you’re doing it.

[Bill Dufour]

Old school trick is to remove the blade then use a long, small stick of wood touching each bearing in turn while running or hand turning Put the other end of the stick into you ear and listen for growling noises. They sell mechanics stethoscopes with long ridgid probes for this
Bill D

[Lee Schierer]

Unless this saw was in a production shop and used for hours every day, I doubt it is the bearings. It won't hurt to remove the belts to check the motor and arbor bearings. I have a Craftsman TS from the 1980's and the bearings in it are just fine. On the other had cold weather and/or infrequent use can cause the belts to take a set which results in excess vibration until the belts warm up. Cracks in belts or pieces missing can also cause vibration.

[Jerry Bruette]

Old school trick is to remove the blade then use a long, small stick of wood touching each bearing in turn while running or hand turning Put the other end of the stick into you ear and listen for growling noises. They sell mechanics stethoscopes with long ridgid probes for this
Bill D

A long screwdriver or pry bar with a plastic handle works well too.

[Bill Dufour]

A screwdriver has the advantage that it will not scratch up the inside of your ear. And it is too large to touch the eardrum if something bad happens.
Twenty years is not bad for grease life if you think about it.
Bill D.

[Ronald Blue]

A screwdriver has the advantage that it will not scratch up the inside of your ear. And it is too large to touch the eardrum if something bad happens.
Twenty years is not bad for grease life if you think about it.
Bill D.

I agree with Bill that the bearings are a good possibility. Grease does lose some of it's lubricating characteristics over time. Especially in a sealed bearing where the quantity is minimal. Do all the diagnostic checks already suggested and even if the belts end up being the cause of the vibration I would make a plan to replace the bearings on the arbor. Motor bearings could also be the culprit. Quality bearings aren't that expensive and it would be good for another 20 years.

[Brian Runau]

Kurt, if your pulleys are misaligned this can create noise and vibration. My opinion, a failing bearing is a high pitched noise.

[Kurt Wyberanec]

Kurt, if your pulleys are misaligned this can create noise and vibration. My opinion, a failing bearing is a high pitched noise.

Thanks guys, I will definitely do some of these checks and see what I can find. I am a light duty professional but it's a one man shop. My biggest challenge is that I haven't done much of this diagnostic work.....quick question though Brian, the noise I have is more of a raaaaaaa kind of sound not as high pitched as say a router running, but not exactly a grumble either. How would I be able to tell if the pulleys have somehow gone out of alignment? The saw did undergo a shop move about 2.5 years ago, but I can't recall as to when I started to notice the noise increasing....might have been before but at least a year now.

2nd question, if it is the arbor bearings, how does one replace them??? Can the arbor be removed and likewise brought to a shop to press them in (I'm assuming they need pressing)?

Thanks again!

[Ronald Blue]

I've dealt with lots of bad bearings in my career. They should roll smoothly and quietly. The first thing I always did was spin a wheel, hub, pulley or whatever. If you hear it then it's not good. Just make sure it's not anything else rubbing. Same with the motor when you have the belts off. As for pulleys moving? Anything is possible but unless you can see signs of movement or you can wiggle it then it's not likely the problem. Others can better advise on changing bearings. If you have the manual there should be a good break down of all parts but you can source bearings locally. Get an SKF or NTN or something similar. NAPA is often a good source for a reasonable price. If the Jet saw I looked up is the same it has the same size on both ends of the arbor. 6203-ZZ bearing.

[Jerry Bruette]

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Here's three pictures of sheave misalignment and how to check them with a straight edge or a string. I always used a string at work, it was easier to carry in my pocket. I don't think you'll have t worry too much about the angular misalignment, parallel might be off but sheave groove would be the most likely culprit. Sorry for the rotation.

For your bearing replacement, you'll have to pull or press the bearings off and you can drive the new bearings on. If you drive the bearings onto a shaft make sure to drive on the inner ring only and if you drive them into a housing make sure to drive on the outer ring only. The bearing size Ron referred to has shields, the zz suffix means shields. A skf bearing would be 6203-2rs the 2rs means a rubber seal on each side of the bearing. Either one will work but the sealed one will keep more crud out.

[Ronald Blue]

For your bearing replacement, you'll have to pull or press the bearings off and you can drive the new bearings on. If you drive the bearings onto a shaft make sure to drive on the inner ring only and if you drive them into a housing make sure to drive on the outer ring only. The bearing size Ron referred to has shields, the zz suffix means shields. A skf bearing would be 6203-2rs the 2rs means a rubber seal on each side of the bearing. Either one will work but the sealed one will keep more crud out.

The original apparently is shielded. That number came right off their parts list. A very common bearing and easily sourced though whichever he chooses. I agree the sealed might be the better choice.

[Bill Dufour]

I like to take the old bearings and grind the outer diameter down a tiny amount. Then take them apart and anneal the inner race and drill it out a fraction. Use those old races as spacers to push in the new bearing.
Bill D

[Kurt Wyberanec]

Hey all, finally got into the machine this week and here is what I discovered....

Could not tell where the noise was coming from...it was too loud and overwhelmed me to pin point it though I was inclined to say the Arbor....

Then I took the belts off...ran the motor and motor was very quite. Again ARBOR....

While inspecting the Arbor I could definitely find a place through rotation where there were 2 distinct click sounds one forward and then when turned back at a different spot. To me it sounded like a bearing but could also simply be something that was not set in place...

I discover that the allen screws that hold the pullys onto the shaft (or maybe they located on the keys) weren't tight....tightened those down and those clicks went away significantly....was the pully just not fitting snug against the shaft?

I put the belts back on fired her back up and ...........still noise, but possibly decreased.....next step....

I took them back off and tried to find this erroneous movement I mentioned and I really couldn't. I could feel it but it was not apparent where it could come from so I was starting to look at how can I remove the arbor to have the bearings replaced because surly that's what it must be. When I started looking around I said let's see what else there is here....the only other locking part I could see is the retaining nut on the end of the arbor shaft. It is a locking nut and likewise didn't think it could come loose but I decided to put a socket it on it and see if it moved.....and.....it did!! Not very much, probably not even an 1/8th of a turn, but it did snug up just a hair....turned the shaft by hand....clicking GONE!! Belts back back fired her up and noise level down tremendously. It's been making the noise so long that I can't quite remember how quiet this saw was before but it is much much less now.

So, did I fix it? I don't know, maybe, or might just be a band aid but for the moment my anxiety level can go down a bit. I am still going to upgrade, but maybe this worked.....My though is that perhaps there was just a minute amount of play on that shaft and it allowed either the shaft, pully, or keys inside to move that tiny amount and shift during rotation and maybe this snugged it....or maybe it just snugged worn parts closer together and works better for now.

Open to everyone's thoughts on this!!

[Jerry Bruette]

I'm not familiar with the Jet saw you have, but I'm having trouble visualizing the nut you tightened. Could you post a picture?

[Brian Runau]

Thanks guys, I will definitely do some of these checks and see what I can find. I am a light duty professional but it's a one man shop. My biggest challenge is that I haven't done much of this diagnostic work.....quick question though Brian, the noise I have is more of a raaaaaaa kind of sound not as high pitched as say a router running, but not exactly a grumble either. How would I be able to tell if the pulleys have somehow gone out of alignment? The saw did undergo a shop move about 2.5 years ago, but I can't recall as to when I started to notice the noise increasing....might have been before but at least a year now.

2nd question, if it is the arbor bearings, how does one replace them??? Can the arbor be removed and likewise brought to a shop to press them in (I'm assuming they need pressing)?

Thanks again!

Sorry fell off the planet a few days.

[Brian Runau]

I like to take the old bearings and grind the outer diameter down a tiny amount. Then take them apart and anneal the inner race and drill it out a fraction. Use those old races as spacers to push in the new bearing.
Bill D

Excellent tip. Brian

[Bill Dufour]

Sounds to me like the bearings wore a little and the preload was gone. Tightening the nut restored the preload. Yes I know ball bearing do not really have preload like tapered roller bearings but the same idea applies.
Bill D

[Kurt Wyberanec]

Sounds to me like the bearings wore a little and the preload was gone. Tightening the nut restored the preload. Yes I know ball bearing do not really have preload like tapered roller bearings but the same idea applies.
Bill D

I won't pretend to know a lot about how they work, but if my understanding is correct, what you said might very well be the case. If that's the case do you think that the preload spring would have to be replaced or would tightening the nut fix the situation or just extend the time? Thanks.

PS Sorry Jerry don't have a pic right now, it would be the nut that holds the arbor shaft and trunnion together.

[Mike Kees]

It will not be a permanent fix. The bearings need to be replaced. Tightening will be a 'bandaid' that helps for a while.

[Kurt Wyberanec]

It will not be a permanent fix. The bearings need to be replaced. Tightening will be a 'bandaid' that helps for a while.

Great....:(....not what I was hoping to hear

[Bruce Wrenn]

Sorry fell off the planet a few days.


Over at NC Woodworker, there is a current thread on replacing bearing in your saw. The bearing you need will be 6203 2RS. A tip for heating bearings, use a light bulb. With bulb turned on, place bearing on top of it for about five minutes. Using leather gloves pick up bearing and drop on shaft.

[Kurt Wyberanec]

Over at NC Woodworker, there is a current thread on replacing bearing in your saw. The bearing you need will be 6203 2RS. A tip for heating bearings, use a light bulb. With bulb turned on, place bearing on top of it for about five minutes. Using leather gloves pick up bearing and drop on shaft.

I'll have to look further into this thanks... the biggest headache I can see is how to get the arbor mount out to even be able to change the bearings... really don't want to take the top off the table that can be a real pain to get back straight... so it goes

[Maurice Mcmurry]

Does anyone know how important it is to use a bearing heater during reassembly when replacing bearings? I have not used one. I have read and been told that to do the job properly a bearing heater is required. I have done several replacements that did not last nearly as long as OEM. I also see bearings with the same size numbers in price ranges from $10 to $100 dollars.

[Jerry Bruette]

Does anyone know how important it is to use a bearing heater during reassembly when replacing bearings? I have not used one. I have read and been told that to do the job properly a bearing heater is required. I have done several replacements that did not last nearly as long as OEM. I also see bearings with the same size numbers in price ranges from $10 to $100 dollars.

Depending on the size of the bearing you don't have to heat it to put it on. SKF makes a set of bearing drivers for mounting bearings up to about 2". If you're mounting a bearing on a shaft you drive on the inner ring, if you're mounting into a housing you drive on the outer ring. If the shaft is in a housing you would drive on both inner and outer rings. Any bearing over 2" should be heated and mounted onto the shaft. A little oil on the shaft or in the housing will help with the mounting process. Never use a anti-seize product for mounting bearings.

If you hang around the SKF website you'll find troubleshooting information and info on how to mount and dismount bearings the proper way. It'll also tell you the most common reason for bearing failure is improper or bad mounting techniques.

[Bruce Wrenn]

Does anyone know how important it is to use a bearing heater during reassembly when replacing bearings? I have not used one. I have read and been told that to do the job properly a bearing heater is required. I have done several replacements that did not last nearly as long as OEM. I also see bearings with the same size numbers in price ranges from $10 to $100 dollars.


Today's bearings are much better than they used to be. Price doesn't always translate to quality. As an example, on daughter's Honda Civic tensioner bearing failed. Replaced it with a $17 bearing from NAPA, which lasted less than six months. Replaced that bearing with a $1.99 bearing from Fastenal, which now has over 300K miles on it. FYI, bearing is a 6203 2RS, same as in saw. The 6203 is probably the most common bearing in usage in the world.

[Maurice Mcmurry]

I put front wheel bearings in our Toyota 3 times. The third time the parts counter guy insisted that I check out the torque wrench as well as the axle puller and front wheel drive bearing press kit.

[Gustav Gabor]

I've found that heating bearings, along with cooling the arbor shaft has worked really well for me so far, particularly on bearings larger than 1 1/2" od.
I cool the arbor shaft in a freezer for at least 2 hours, and heat a socket that is just a few hundredths smaller than the inside diameter of the bearing to about 350 - 400 degrees F.
With welders gloves or vise grips, I place the very hot socket into the bearing to transfer the heat and expand just the inner race of the bearing. I check with a digital temperature gauge, and once the inner bearing race is up to about 250 degrees, I take the shaft out of the freezer, quickly wipe the condensation off the area the bearing will mount to, remove the socket from the bearing, and immediately drop/place the bearing onto the shaft.
It's a one shot deal, and has to be done really quickly, otherwise the bearing will shrink onto the shaft before it gets to the final position.

I find that by heating just the inner race, the bearing grease isn't overheated as it would be if heating the entire bearing in an oven.
A proper bearing heater would of course be the way to go, but as I have yet to win the lottery, not happening anytime soon ....

[Maurice Mcmurry]

The guy who told me about the benefits of using a heater has experience with routers. He has several old ones that he keeps going. His heating technique is much like Gustav's

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[Robert Engel]

I'll have to look further into this thanks... the biggest headache I can see is how to get the arbor mount out to even be able to change the bearings... really don't want to take the top off the table that can be a real pain to get back straight... so it goes

Hey, Kurt I had this saw (2001) and have been through the procedure. The set screws on my pulleys were loose, too and I think this caused the bearings to go bad. But they lasted 21 years.

You have no choice you have to take the top off in order to get to the arbor bracket set screw. Over on the NCWoodworker's site one knowledgeable guy said replace the allen screw with a bolt. This enables you access it with the top on which helps in realigning the arbor bracket. I HIGHLY recommend you do this, as it will enable you to realign the arbor with your zero clearance throat plates after the top is on and the miter slots aligned.
473957

The huge mistake I made was not realizing the retaining nut (opposite end of arbor) is left hand thread - don't forget this! I ended up stripping it with an impact & luckily I had a friend weld up, rethread it and get a new nut.

To get the arbor assembly out, you have to loosen the retaining screw and work the arbor bracket parallel to the height adjustment threads with a little wiggling it will come loose.

The bearings came out and installed very easily on mine. Good luck getting the table on and off and realigned was the hardest part. I purchased the bearings from Jet, but there are replacements I'm sure just as good. Maybe not necessary, but I also replaced the wave washers.

[Kurt Wyberanec]

Hey, Kurt I had this saw (2001) and have been through the procedure. The set screws on my pulleys were loose, too and I think this caused the bearings to go bad. But they lasted 21 years.

You have no choice you have to take the top off in order to get to the arbor bracket set screw. Over on the NCWoodworker's site one knowledgeable guy said replace the allen screw with a bolt. This enables you access it with the top on which helps in realigning the arbor bracket. I HIGHLY recommend you do this, as it will enable you to realign the arbor with your zero clearance throat plates after the top is on and the miter slots aligned.
473957

The huge mistake I made was not realizing the retaining nut (opposite end of arbor) is left hand thread - don't forget this! I ended up stripping it with an impact & luckily I had a friend weld up, rethread it and get a new nut.

To get the arbor assembly out, you have to loosen the retaining screw and work the arbor bracket parallel to the height adjustment threads with a little wiggling it will come loose.

The bearings came out and installed very easily on mine. Good luck getting the table on and off and realigned was the hardest part. I purchased the bearings from Jet, but there are replacements I'm sure just as good. Maybe not necessary, but I also replaced the wave washers.

Hi Robert, I'm very confused....I had no idea that nut was left hand and that is in fact the nut that I snugged just a tiny bit, but righty and the noise improved! I only moved the tiniest amount which made me think I snugged it, did I actually loosen it?

The though of getting that table aligned back really bothers me....do you think it is at all possible to get it off without removing the table? And did you remove the bearings yourself or have someone do it? Also, did you replace the load springs and anything else that's in that assembly?

Thanks!

[Bill Dufour]

Classic bearing heater trick is to set it on top of an incandescent light bulb. Or use a skillet of hot oil. For wood shop size bearing should never need to heat or cool. maybe planer main cutterhead bearings.
Dry ice is cheap so is a CO2 extinguisher or paint ball tank. Liquid N is too cold and risks cracking the metal.
Just be carful that it is a straight push no lever action that will break a casting arm off.
Bill D.

[Mike Monroe]

My funny bearing story has to do wiht my old 1997 F-150. A front wheel bearing was going out but I couldn't tell which one. I had a mechanic ride with me and he said it was the right front. So I ordered a new front wheel and installed it on the right front. Noise is still there in the front end, so I take the wheel bearing I just took off the right front and put it on the front left. Noise gone. After getting the left front bearing off it was plain to see that the wheel bearing was bad. Drove that truck for 298, 854 miles. The only thing I replaced on it were tires, brakes, a headlight bulb, plugs, the alternator, a wheel bearing, and two batteries (the OEM battery lasted 11 years).

Oh and I've replaced the bearings on my Delta Unisaw after 20 or so years of use.

[Jerry Bruette]

Hi Robert, I'm very confused....I had no idea that nut was left hand and that is in fact the nut that I snugged just a tiny bit, but righty and the noise improved! I only moved the tiniest amount which made me think I snugged it, did I actually loosen it?

The though of getting that table aligned back really bothers me....do you think it is at all possible to get it off without removing the table? And did you remove the bearings yourself or have someone do it? Also, did you replace the load springs and anything else that's in that assembly?
Thanks!

Maybe while you were moving the hex nut you moved the spanner nut that it's inside of and that may have made the noise go away. If the wavy washers are still wavy they should be good. The only time I've replaced one is when it's broke or got lost. I think the only reason there's wavy washers in that assembly is to take up the movement that could happen from the shaft assembly getting warm. When the shaft warms up it gets longer. The bearing on the blade end of the arbor should be held so the blade never moves and the other end would have the wavy washer to take up the thrust from the assembly warming up.