Jet 1642 Motor gone bad

[Jim Underwood]

Welp. It finally happened. Sometime last year I began to hear a noise in the motor of my Jet EVS 1642. Of course it was just out of warranty. I bought it May of 2009 and started realizing the noise sometime last fall or so...
Well Saturday I was in the shop turning some coffee table legs and the noise got louder and louder. A look at the pulleys while running shows the motor shaft wobbling while motor is making a 'scrape, scrape, scrape' metal-on-metal noise...
I took the motor off clamped it to my bench, and attempted to make the shaft wobble or make noise. It feels smooth as can be... Put it back under power and the noise and wobble comes back.
Jet technical support guy said his went bad too, and had to replace it. The local motor rebuilder say it's cheaper to replace it than rebuild it.
It's still not cheap at $460 plus shipping.
Dang it. Wish I'd heard that noise before the warranty ran out.
Why's a motor going bad on a 6 year old machine anyway? It's not like I run the dog crap out of the thing running it couple times a month.... :mad:

[Tim Rinehart]

The person at Jet who does the math like insurance companies do with actuarials, really did his job on that one. Generous appearing warranty when purchasing, but product fails outside warranty and generates parts sales for company. Sorry to hear that. Have you eliminated any possibility of the two spindle bearings contributing to the racket or any wobble? If so, would be a good time to go ahead and change them out, along with your belt. I've replaced spindle bearings on my 1640 when I had it...not a bad job. Was able to use a wood block to gently tap out the bearings.

[john patrick]

Jim, I just had the front bearing go out in my one year old 1642 230V motor. The symptoms were somewhat similar: under power, and at lower rpm, there was a noisy metallic scraping/clicking sound. With power and pulley off, it seemed to turn smoothly. Jet quickly sent me a new motor and when I pulled the old one apart, the front bearing was obviously gone. $15.00 later, she's as good as new and a spare on the shelf. I've never redone a motor before, but it was pretty easy. Suggest you may not have much to lose to get a mechanical buddy for support, a set of bearing pullers, and go for it?

[Jim Underwood]

I'll pull the motor apart tonight or tomorrow night and see what I can see. It can't be the head stock spindle (or the inverter) because I tried it with the belt off and the motor shaft wobbles too much and makes noise only under power.

On the bench I can NOT make it wobble or make noise even after I clamp it to the bench and pull up or push down as hard as I can.
Gotta be something in the end housing....

[Kyle Iwamoto]

I was also thinking you may want a second opinion on the repair. Sounds like a bearing, and I can't see how changing 2 bearings can be more expensive than buying a new motor. I've not yet taken apart a TEFC motor, but I wouldn't think it's that hard. Thanks John for the info, I'll watch my bearings and hopefully if they do fail, it's before the warranty runs out.
Perhaps the time and labor cost involved to replace a bearing or 2 is not "worth" the effort, and it is cheaper for Jet to send a new motor assembled overseas.

[Dwight Rutherford]

I would take the motor to a local shop and have them check it out. If it is apparent it has to be replaced you see if you can replace the motor through another vender. I have found Jet's prices quite high for parts.

[Robert Henrickson]

The person at Jet who does the math like insurance companies do with actuarials, really did his job on that one. Generous appearing warranty when purchasing, but product fails outside warranty and generates parts sales for company.

Five years is much better than what some other companies offer.

[charlie knighton]

i feel fortunate with my 1642....mine was 1 1/2 hp.....was yours 1 1/2 or 2 hp???????

bought mine at ricchmond symposium 2008?????

[Rich Aldrich]

If it is just bearings and it sounds like it is, pull it apart and go to a Motion Industries, Applied Industries, Kaman, or similar store. These are industrial type places. Ask for an SKF, Timken, or other good name brand. These bearings are probably sealed since I don't remember seeing grease fittings on my 1642 motor.

A motor shop can test the motor and make sure the rest is fine. For them to rewind the motor, it is cheaper to replace it. We dont rebuild motors until 40 HP or larger. We will change bearings in the smaller motors if we are sure that is all that is wrong. We just changed bearings on a 3 HP motor on one of the FD fans in the boiler room at work (I am responsible for the boiler room, so it was my call. We did it after looking at it with one of our electricians - rather the electrician/millwright changed the bearings).

[Joseph M Lary]

Jim, I think we bought our Lathe's at about the same time. I'm on my third motor, knock on wood both mine where under warranty. I have a grinding noise starting in the head stock and I think it bearings. I use my lathe a lot at times 16 to 20 hours a week .Keep us updated on the motor I would like to no how it turns out and where you get the motor .

[Robert Henrickson]

Jim, I think we bought our Lathe's at about the same time. I'm on my third motor, knock on wood both mine where under warranty.

I bought mine in 2008. Still on first motor [knock on wood!], after literally hundreds of bowls, as many plates, and almost as many hollow forms, plus lots of other stuff.

[Mike Tilley]

Jim I also am having trouble with my 1642 not sure what the problem is!
While turning it sometimes just loses power and will free wheel to a stop. If I push the reset button on the inverter it will reset and start again it may run for a few minutes or continue to run for as long as I'am turning. Called jet a while back as I thought it was the inverter but tech said he didn't think it was bad.
anyone have any ideas? Motor doesn't run hot just shuts down.

[Roger Chandler]

Jim I also am having trouble with my 1642 not sure what the problem is!
While turning it sometimes just loses power and will free wheel to a stop. If I push the reset button on the inverter it will reset and start again it may run for a few minutes or continue to run for as long as I'am turning. Called jet a while back as I thought it was the inverter but tech said he didn't think it was bad.
anyone have any ideas? Motor doesn't run hot just shuts down.

Are you plugged in to a GFCI outlet? If so, that could possibly confuse the inverter.

[Mike Goetzke]

Jim - I tried sending you a PM but your box is full but here is the info I tried to send:

Jim - I have a PM3520B that's about 1-1/2 years old. Right about a year I could hear a noise from the motor at slow speed or coast down. As suggested by a Creeker I bought a $4 mechanics stethoscope at Harbor freight and determined it was a bearing. Took about 3 calls to PM but they eventually sent me a replacement motor under warranty. Guess what? They didn't request the OEM motor be sent back. So I tore it apart (actually pretty easy - only special tool really needed is a gear/bearing puller). This 3-phase motor doesn't have brushes - pretty simple design. Found out they didn't properly remove some metal casting flashing and small pieces of this got into the bearings. So I cleaned up the flash ordered new bearings and now have a spare motor. Sounds like you have bearing problems so worth a try.

Don't know if the PM & Jet share the same motor but I might give some thought about selling my spare.



Mike

[Jim Underwood]

The shaft is bent.
I took the motor apart last night. The bearings are smooth, and they seem to be fairly tight in the end caps. But the armature has been scrubbing the laminations of the coils mounted in the case.
I mounted the armature between centers of my lathe and rotated by hand. You can see the "lope" even at hand speed.
I thought I might be able to replace it with a Baldor motor, but can't seem to find specs that match. I'd hate to buy a new motor and it not work...

313438
Here's the pix of the armature and coil laminations. You can see where they've been in contact with each other. The laminations have been shifted over. Eventually, they'll pinch the coils if they haven't already....
313439
313440

[Mike Goetzke]

See the cooling fins in your center picture - that's where mine had all the casting flash left on it (thin as tin foil). If the bearings spin really freely that's a sign that they may be bad. Don't see how the shaft could have bent though.

Mike

[Dwight Rutherford]

For a replacement motor try "Automationdirect"

[Jim Underwood]

Mike, I've run into other posts where folks have said the PM and Jet are using the same inverter. If that's the case, I don't see why the PM motor wouldn't work...
Might have to reprogram it though.
Is yours a 3phase 230 volt motor?
Might have to do some research on this...

I've been doing some perusing on the internet. Seems like this motor has given an awful LOT of people trouble. Now I'm just a bit ticked off at Jet for it. I'll do some more examinining of the motor just to TOTALLY eliminate bearings, but I don't think that's the problem...
I'm really tempted to remove the armature from the shaft just to see what's under there....

[daryl moses]

A lot of people may not want to admit it but I would just about bet that is the same motor that's in my Grizzly GO733 or could be interchanged. Maybe the same as some of the other "clones" as well. Might not be any cheaper but I would sure as heck check.

[Roger Chandler]

A lot of people may not want to admit it but I would just about bet that is the same motor that's in my Grizzly GO733 or could be interchanged. Maybe the same as some of the other "clones" as well. Might not be any cheaper but I would sure as heck check.

Not sure on that, Daryl.......I have not heard of one motor failure on a G0733. Might be interchangeable if it will mount up with the Jet mounting plate. :confused: More likely the motor from a G0632 clone would fit it.

[Mike Goetzke]

Might be worth a call to Jet to see if they can help you out even out of warranty .

Also, my bearings for my PM motor were less than $20 from Accurate Bearing. I would at least try them before I tried to remove the armature.


mike

[Izzy Camire]

I was at Woodcraft last night looking at the Jet 1642 I thought it was a decent moderatly priced lathe. After reading this thread I am not sure buying is a good idea.

[Jim Underwood]

Izzy,
The more I read, the more I find that it was a bad batch of motors. I suppose one would have to get one of the current batch and use it for 6 years to see if the new ones were better.
I've spoken with the Jet folks. We'll see if they'll give me some help with this. Gotta find my serial number first though.

[Robert Henrickson]

Izzy,
The more I read, the more I find that it was a bad batch of motors. I suppose one would have to get one of the current batch and use it for 6 years to see if the new ones were better.

And as I said earlier, I've had one for 7-8 years without a motor problem and with extended use.

[Jim Underwood]

Robert,
And then there's Joseph, who says he's on his third motor...

[Brad Adams]

I definitely wouldn't by a motor from jet. Just find a 1 1/2 hp c face motor to match. Oem motors are notoriously expensive.

[david privett]

If the motor shaft is bent I do not believe that could be anything else but a defect in manf. quality control . With a belt drive I do not believe that you could ever place enough torque back threw a belt to cause a bent motor shaft. It would be twisted not bent anyway.

[Tony Cognato]

You may want to try Grainger's. I have replaced many many motors on various machines over the years as an electrician and have never been stumped in finding a match up.

[Jim Underwood]

Doesn't look like Jet is going to help me out. If they do I'll be pleasantly surprised.

I've been told that after 7 years (the date the motor was manufactured- NOT the date I bought it) it's "normal wear and tear" for a shaft to bend.

Right. And I'm a friggin panda bear. :rolleyes:

I posted on this forum on May 8th, 2009 the very day I bought the thing. I also posted on this forum on May 12th, 2009 when it arrived on my dock. I probably put it together that night or the next night, so it's been six years almost to the DAY since I first turned it on in my shop. And it began to exhibit these symptoms sometime last summer, just out of warranty...

Just my luck.

If anyone can give me any help finding the right aftermarket motor, I'm all ears. I'm not exactly sure what to do. Last time I tried to get something aftermarket to work for my 1014 it didn't turn out so well. The aftermarke start run capacitor I bought let the smoke out in less than a second or two....

[david privett]

well the first thing I would do is look at the motor tag and see what is the frame number listed for the motor that should get you started as where to look of course there will be other info req. but the frame number is good to start with.

[Cary Falk]

I still can't picture how the shaft could get bent. I still think I would try new bearings before I sunk money into a new motor. As David said, start with the frame number. Unfortunately mind did not have a frame number on the motor tag. If the VFD is the same between the 1.5 hp and the 2hp I would consider upgrading to a 2hp motor now. If you can get the shaft size right and the motor is approximately the same size you can always make an aluminum adaptor plate to mount it up. The good news is you don't have to worry abut letting the smoke out of start/run capacitor this time. :)

[Jim Underwood]

It is a two HP motor. That's why I'm so surprised that it's failed already.
As I think about what tech support told me today I realize I can conclude one of two things.
Either he's telling the truth and this is the quality of the product, such that it will only last until the warranty is up. Granting this a new motor won't be any better than an old one. If this is the case then I'm no longer a fan of Jet products.

If not then there really was a bad batch of motors and I've just been screwed. And Jet won't admit to it and so I'm either stuck with buying a new motor in hopes it'll last longer than the original. Or I can take a chance on an aftermarket motor in hopes I can make it work with the EVS.

Either way I'm not a happy camper. I don't feel served well.

[charlie knighton]

what was strange was the 2 hp motor had 5 year warranty and the 1 1/2 hp motor had 1 year warranty......and the problem seems to be coming form the 2 hp motor

[Jim Underwood]

Since the bearings for this motor were only $4, I'm gonna try em and see if it makes a difference.
I'll let you know what happens.

I'm also very curious whether the 2HP PM3520 motor is the same since it uses the same inverter. There's a thread on this forum where someone says it is the same motor...

[Joe Kaufman]

The motor would have to be for the original PM 3520, not sure about A, and the B definitely won't fit w/o shortening the output shaft and machining a new keyway.
The B shaft is over 6" long and the keyway is only the last 2" of the shaft.
Joe

[john taliaferro]

I would have to say the motor shaft was ether bent by the factory when assembled or not balanced well ,which took 6 years to hurt the bearings . I would try to fix the armature and replace the bearings .

[Joseph M Lary]

Jim, On my first motor replacement, the guy I talked to told me they had a bad batch of motors , told me to take off the label and sent it to him that would ship me out a new motor and to keep the old motor. The next time I called the same guy, had all the information form the first time . He wouldn't admit to the bad batch this time and said I would have to take it to a jet service center for the warranty service. I know the guy that manages the service center and he said they did not want to replace the motor but they did , this all happened in the first 2 years. I haven't had any problems . Powermatic and Jet where both owned by the same company at one time WMA tool group I think it was .

[Jim Underwood]

Joseph,
Well Jet basically told me that it's out of warranty and they're not going to do anything about it. I haven't called customer service and raised a stink yet. I'm contemplating it though. I don't know if it's worth the hassle...

Dunno that it's worth the hassle of trying to make something else fit, either. If I go aftermarket, then I have to make sure it's EXACTLY the same kind of motor (and a lot of details are sketchy) as well as being machined for the pulley and the shaft being the right length. What's the chance of that? If I use a Powermatic motor, I'll have to make sure the shaft is correct length and machined for the right pulley... I'm inclined to think that I'd be better off just buying the OEM motor and then selling it the whole rig so I can buy a Vicmarc or a Robust...

I started putting the bearings in last night. I haven't gotten it all back together yet. I don't think it's going to make any difference, because I really think the shaft is substandard. I took a close look at it while I had the thing between centers. They've just taken some hot rolled shaft, and turned it quickly and roughly on the lathe, then compressed the armature to the shaft. You can see the "machinist" didn't bother to true up the raw stock (with scale still on) in the chuck before turning it. You can still see the eccentricity of the hot roll surface.... I mean that it really LOPES. I was taught in machine shop class, that you should always start by chucking up the raw stock and adjusting the chuck jaws (machinist chuck jaws are independently adjustable) until the stock runs true as possible, and only then start turning. This "machinist" didn't even bother getting it close....

[Dave Cullen]

Is the motor a standard NEMA size, or is it something unique? If it's standard, I'd be looking for a Baldor.

[Sonny Kemp]

Joseph,
Well Jet basically told me that it's out of warranty and they're not going to do anything about it. I haven't called customer service and raised a stink yet. I'm contemplating it though. I don't know if it's worth the hassle...

Dunno that it's worth the hassle of trying to make something else fit, either. If I go aftermarket, then I have to make sure it's EXACTLY the same kind of motor (and a lot of details are sketchy) as well as being machined for the pulley and the shaft being the right length. What's the chance of that? If I use a Powermatic motor, I'll have to make sure the shaft is correct length and machined for the right pulley... I'm inclined to think that I'd be better off just buying the OEM motor and then selling it the whole rig so I can buy a Vicmarc or a Robust...

I started putting the bearings in last night. I haven't gotten it all back together yet. I don't think it's going to make any difference, because I really think the shaft is substandard. I took a close look at it while I had the thing between centers. They've just taken some hot rolled shaft, and turned it quickly and roughly on the lathe, then compressed the armature to the shaft. You can see the "machinist" didn't bother to true up the raw stock (with scale still on) in the chuck before turning it. You can still see the eccentricity of the hot roll surface.... I mean that it really LOPES. I was taught in machine shop class, that you should always start by chucking up the raw stock and adjusting the chuck jaws (machinist chuck jaws are independently adjustable) until the stock runs true as possible, and only then start turning. This "machinist" didn't even bother getting it close....

Jim if you would be interested in selling it just like she lays Email me a price and I might be a buyer.

[Joseph M Lary]

I got the old motor if you want it .I was going to see if it cold be fixed ,but after about 6 years I don't think that willever happen .I never pulled it apart ,it ram when I took it off , sounded let some thing was loose inside .I do not think it was the shaft .maybe you can use it for parts to fix yours .

[John K Jordan]

Jim, based on experiences I've had, if I thought it was a factory defect I would definitely escalate it through Jet.

Here is one story: I had a Honda XL250 that suddenly blew the engine. Though far (years) out of warranty, I proved on disassembly that it was a factory worker's defect. Honda ended up replacing the entire engine and throwing in a new battery.

I think the key was my letter writing. Forget phone calls, you can get someone who can dismiss you on a whim and hope you will go away. They can later deny they even said what they did. With a real letter, written on paper, they have to actually think before writing a response.

In my case, I sent a letter to Honda of America, a copy to Honda of Japan, a copy to Ralph Nadar who was heavily into consumer protection at the time, and a copy to some other consumer agency (forget who). The letter and copies showed the recipient list so Honda of America knew someone else was aware of the issue and might pay attention to their response. They couldn't just ignore it and pretend they didn't know anything about it.

My letter carefully documented exactly what happened, the details of I discovered about the engine, the name and response of the local Honda dealer ("sorry, can't help you"), the financial and use loss I suffered, and how my opinion of the Honda company had changed. The result: Honda actually sent a real person, a regional representative who drove at least 100 miles to look at my motor! By coincidence I walked into a Honda dealer just as the guy was asking the owner if he knew how to find me. Ha!

If I had your motor, I would document the same way, include photos, get a local machine shop and motor shop to take a look and if they agree the workmanship is substandard, include their findings along with company name and contact info. I would include my projected financial loss including loss of use. I would state how my respect for their reputation for quality and service was being stretched thin by this experience. I would mention this issue is being discussed right now on an international woodworking forum read by thousands of Jet customers, many whose future purchases might be influenced by Jet's response. I would send the letter at least to the top of Jet and the parent company, first researching who is in charge. Optionally, you could have a lawyer send the letter on his letterhead but that would cost some money.

If you are convinced the failure is actually a result of a factory defect and not from normal wear or neglect or abuse, this may well be worth your time.

JKJ

[Brad Adams]

I don't think the manufacturer is at fault on this one. There is no way you have used this lathe for over five years and not noticed a bent shaft on the motor. You said yourself, the sound started last fall. So you kept using it even though it was making noise, without investigation? I call B.S. on this one. The bearings were probably going bad last fall, and the continued use caused the failure. I don't think its fair to pile on the manufacturer for an obviously out of warranty lathe that has been used for over five years without problem. Making a "stink" with them is wrong. Man up and buy a new motor.

[Jim Underwood]

Thanks all for the kind offers. Hold the thought for a bit.
I put the new bearings in this evening, and while it might have been more quiet (I won't know for sure til it's under load) it definitely didn't cure the bent shaft.
So. Tomorrow I'm going to do two things;
First I'll take the motor to my local motor shop and see what it'll take to match it up. Then I'll have price and availability on an aftermarket motor. And that just might help the rest of you going through this same problem.
Second I'll call Jet customer service and ask what they're going to do for me. I have no real basis for expecting anything legally since warranty ran out. But the decent thing for them to do is, if not replace the motor, at least give me a discount or free shipping or something. If they don't admit the bad batch of motors and keep to the "normal wear and tear" line, I'll just not buy anything from Jet. Ever. Again. Because I can't expect any better quality than that can I?
I've had experience with two 1014 lathes( my first one was screwed up from the factory and I had it replaced) and this 1642. It just seems like the quality control isn't there...
So. We'll see.

[Jim Underwood]

Hey Brad,
You're welcome to your opinion, but in mine, you're wrong.
That shaft shouldn't have bent under normal use.
Period.
And it's well documented on this and other forums that Jet had a batch of bad motors at the same time I bought mine.
Should I be penalized because I didn't run the dog crap out of mine and the defect didn't show up as soon as others did?

[Brad Adams]

Under normal use it probably wouldn't have bent. You said it yourself, the noise started last fall. Running a motor with bearings going out, which was probably the noise you heard, never ends well. I see it all the time on motors. I'm sorry it went bad, but blaming the manufacturer is wrong on a six year old lathe.

[Jim Underwood]

Right. So "bad bearings" cause a bent shaft? I don't think so. It's the other way around.
The shaft was bent and that's what caused the bearings to "fail". In fact, I don't think there's anything wrong with the bearings and I've maintained that all along. They are smooth as silk...
I've seen the machining on this motor and described it to you. I've seen Jets "quality" on my original 1014 like a pulley that wasn't concentric with the hole. Jet's machining is sub par. This motor has had NOTHING done to it that should cause its failure. It should last more than six years....

[Dwight Rutherford]

I'm with Brad on this. Question, if you heard a strange noise in your car, would you just ignore it and continue to drive it until it died and then blame the manufacturer?

[Jim Underwood]

As if the shaft wouldn't be bent if I hadn't kept running it?
Nah.
Either the shaft was bent from the factory and finally showed up six years later, or it was defective because the steel was too soft or there was a void, crack or something else in it.
An electric motor isn't like a car engine where if you run it without oil you'll ruin it. Or brakes where if you continue keep driving after it makes metal on metal noise you'll be buying rotors as well as brake pads.
If the motor began making a barely noticeable noise, and then slowly got worse, then the problem was in the shaft to begin with. It's not like stopping was going to prevent anything, Especially if it wasn't bearings.
And it's NOT the bearings. I've replaced enough bearings over the past thirty years to know what bad bearings look and feel like.
I mean think about it. There's only like three moving parts in this motor. Two bearings and an essentially one piece armature consisting of the shaft and rotor. There's no brushes, no commutator bars. Then there's the stationary case and it's stationary coil lamination assembly.
That's it. Very simple.
Now if begins making noise what possibly has gone wrong? Bearings. Those have been eliminated. The case coil assembly could have come loose. That's been eliminated. The rotor could have been coming apart. That's been eliminated. Or. The shaft could be bent. That's what it is.

Now there's only two or three possible scenarios that could explain how the shaft came to be bent.
One, it was bent from the factory and slowly got worse over the years.
Two, the shaft wasn't bent, but something I did caused it to bend.
Three, the shaft had a defect (either machined in, inherently from a void or crack, or from substandard materials) and bent from normal use.

Obviously I lean towards a combination of reasons one and three. You could say I suppose that normal use caused the problem, but I maintain that a motor should NOT exhibit problems from a bent shaft from normal use unless problems one and three were present.

Now at least two people condemn me for continuing to run the thing after it started making noise. Here's the deal though. First thing I did was check the part list. There are no parts available for the motor. The only thing you can actually replace are the bearings.- from an aftermarket source. And when roller bearings go bad they don't go; "knock, knock, knock", they go "growl". (Unless it's a preload problem and then it's not technically bad bearings. And in this case it's a moot point because there AIN'T no preload.) So it's not like lack of use prevented the shaft from bending or made it so it could be fixed. No. By that point the damage was already done. You can't replace the shaft from parts available from Jet, and no motor shop will fix anything this small- because it's just not cost effective.
And it was already out of warranty.

So what am I supposed to do? Stop using it? Why? The only "fix" is to replace the motor.
So I chose to get as much use out of it as I could knowing the pulley shaft was wobbling. The ONLY thing you could fault me for is not calling Jet immediately.

I still maintain that the shaft should not bend under normal use, and certainly not from very occasional use..

[charlie knighton]

I still maintain that the shaft should not bend under normal use, and certainly not from very occasional use

I agree.....not sure how would one go about bending a shaft......only thing I can think of is to lock shaft and beat it with sledge hammer, somehow I cannot see a turner doing that.

[Roger Chandler]

It sounds likely to me that the metal in the shaft was not treated to harden as well as it should have been [defective] and heat inside the motor has warped it..........that would explain why you have it manifesting after 5 years of use..........just my 2 cents!

[Jim Underwood]

Whenever I resolve this, I'm probably going to cut the armature apart and inspect the whole shaft.
I don't think it was hardened.
Something happened to the middle of the shaft....

[Dan Hintz]

A hardness test along the length of the shaft wouldn't be hard to do... though it might not take into account case hardening.

[Jim Underwood]

Here's a quote from another forum which explains what I think really happened:


"From a mechanical engineer’s perspective – I’d guess the shaft has been bent since the beginning and it’s just taken this much time to get worse because of the light use. Your jump rope analogy is pretty good. If it was bent even just a little bit to begin with, then the center of mass is going to be off from the center of rotation and will get pulled out due to the centripetal force. Think merry-go-round and sitting right in the center vs. sitting a little off center and getting pulled to the outside. That force gets higher as the RPMs increase so at those really high speeds it’s applying more force out away from the center making the metal bend more than what you can generate by hand. Add to that Force + Time = Fatigue so as the metal fatigues it becomes easier to bend. As the fatigue gets worse, the metal bends more and the center of mass moves further away from the center of rotation which makes the force higher which makes the fatigue worse which… You get the picture, right? Sounds to me like you’ve just recently accumulated enough time that the metal of the shaft has fatigued enough and the force at high RPM is warping the shaft enough that the armature is finally hitting the surrounding coil."

[Jim Underwood]

Looks like the motor shop is too busy to help. They're saying the motor has a special mounting that they can't duplicate. I can't really blame them for not wanting to fool with my mickey mouse motor when they're in the middle of a rush job on a 600 HP motor rewind... :rolleyes:

[Jim Underwood]

MMMMmmmmmmmm….. that Crow sure tastes good. A bit chewy though…
Just dropped the motor off at the motor shop. They were kind enough to give me 15 minutes or so. Took the end caps off and inspected. Asked what was the reason I took it apart in the first place – bearings gone bad?
I said, no, the armature was hitting the coil laminations, and I replaced the bearings just in case that was the problem. But it didn’t fix it, because, I said, the shaft is bent.
He says, well sometimes the belt gets tightened too tight, and then the bearings act as a fulcrum and the tension pulls the pulley end away from the bearing, and the center of the shaft bends away from that tension. He says, I can just about tell you which direction the tension is being pulled from where the armature is hitting the coil laminations. And when we pulled it back apart, sure enough, the armature was hitting just about the predicted spot.
The upshot is that he took pity on me and was going to bend the shaft back to true, and trim a bit off with the lathe to make sure it didn’t hit anymore – for less than $100.
And the replacement motor option is kinda dead in the water. The motor mounting was different, a C-face needs a recess to mount in, plus the bolt pattern was different and the clincher was the 5/8” shaft being smaller than a 16mm shaft…
I trust these folks. I’ve been dealing with them for years and years, and they’ve ALWAYS treated me right even when it would have been easy to take advantage. And they do a LOT of business with some REALLY big industry folks here. (They’ve got a couple of 700 HP motor jobs after they finish the 600 HP job, right this minute.)
So, I’ll take their word for it, apparently I did cause the problem. I admit, I was too quick to blame Jet for it.
Mmmmmmm….. Crow. Jest eat it….

[Dave Cullen]

I've never seen a bent motor shaft unless it was whacked by something. Seems like either a design flaw or manufacturing defect to me. I don't think Jet is totally blameless here.

That said, is the bottom line here that the belt was over tightened? Did you put the Fear-Of-God into tightening it? Even if so, I can't imagine a motor failing before the belt.

Anyway, I'm really glad you have a reasonable solution at hand. Is there a corrective action plan (like go easy on the belt)?

[charlie knighton]

thanks for sharing Jim, it was a revalation

[Dan Hintz]

Thanks for the update, Jim, even if it means tonight's dinner is a little less palatable.

[david privett]

Back in the day before serpentine belts and automatic tensioners, I remember hearing that over tightening v belts would cause bearing failure mostly in alternators. But never personally seen it. And using belt deflection to judge how tight was somewhat a personal choice. But never heard of causing a bent shaft, but I do not work with motors very much. curious. I your opinion is the pulley out far enough past the bearings that they could have that much leverage advantage? If so are we back to the shaft being under engineered?

[David C. Roseman]

Jim, interesting update. Be sure to give us another once you get the motor back from the shop. I know overtight belts can cause bearing failure, but a bent motor shaft is a new one to me.

Do you suppose belt overtightening could be the culprit in some of those other reports of Jet motor failure? The 1642EVS has been around quite awhile and is highly regarded. I've heard of very few problems with it.

[Jim Underwood]

Well, that had occurred to me as well. I never moved the belts into a new position until sometime in the past two years... I can't remember if the motor comes attached to the headstock or not, so I don't know if I initially put it on. If I did, I must not have gotten it too tight that first time.
But I didn't think I'd gotten it too tight this last time... Apparently I did.

[Jim Underwood]

As for the shaft leverage question, the shaft is turned down to 16mm (just over 5/8") for the pulley. And the shaft sticks out approximately 75mm (3 inches) from the face of the motor. So the belt tension does have a good bit of leverage on a fairly small shaft.

[John K Jordan]

Wow! Great (and happy)followup!

It was so fortunate you found the right motor guy. You are a real man in my book to even mention this - I suspect many would never admit it and let it drop. Thank you for this info - I'm going to go check the belt tension on my 1642 lathes and the smaller lathes.

I remember my 1642 manual said to let the weight of the motor supply the belt tension, implying no additional tensioning necessary. What it DIDN'T do was warn against additional tensioning. Maybe Jet would add a note in future manuals if you prompted them, or put a sticker on the inside of the belt door.


I've heard it is better for engine fan belts to be a bit too loose rather than too tight - just tight enough to not slip. I thought it was to keep the belts from wearing excessively. (Just had a belt disintegrate on my bobcat, bought used, and I confess I've never checked the belt tightness.) I imagine an over-tight fanbelt might damage an alternator or other component. Thank you again for the education.

This might be good to post in the other forums you mentioned. Maybe many others are overtightening - you might save an untold amount of grief. Perhaps some of the other failures you read about were from the same thing. We all often overdo things - if a little is good then a lot must be better. I once bought several Nova chucks from a guy that had been over-tightened so much the metal in the chuck body had deformed. He must have used a cheater bar on the chuck key!! Took me hours to rework them.

I may put a note on my two and the 1642 used at our club demos. Might be a good note to put in turning club newsletters as well. I wonder if other lathe models have similar belt tightening requirements.

I hope the kind motor guy's efforts fix your motor. Maybe send him a gift card for a resturant or something!

JKJ

[david privett]

kinda makes me wonder how much extra bowing would be caused when you have 25 lbs of unbalanced wood between the centers spinning?

[John K Jordan]

David, The wood is not supported by the motor shaft but by the spindle shaft. The spindle is massive (and with heavy duty bearings) compared to the motor. Flexing or movement in the spindle, if any, would be isolated from the motor by the belt.

[david privett]

yeah your are right I do not know what I was thinking,I guess I was focused on the motor as it being direct drive. duh stupid

[John K Jordan]

Hey, for a moment I thought the same thing when I heard about the bent shaft - maybe it was a big chunk of wood or a massive catch. Then I remembered how that lathe is made! I should have known, I've got two of them in my shop...

[Jim Underwood]

Well phooey. I put it all back together tonight but it still makes noise under power. The guy at the motor shop said it was only off by .0005" after he trued up the rotor.
Something is definitely messed up with this thing.
I'll post a video at some point...

[george wilson]

Asian motors are crappy,just crappy. I had the motor on our 16" x 40" Taiwan made Grizzly lathe short out through the bearings. The museum's electricians said the motor was junk. One problem is the Asian motors do not have the commutator dipped in insulating varnish.

In your case,the problem is probably that Asian motors(and a lot of other stuff they make),just use poor grades of metal. So,your shaft bent. Their electronics are also always questionable. I had a Jet wet wheel grinder that was brand new quit working after just a few hours of use. When I called the Jet repair facility,I got a long lecture from the head idiot on how proud they are of their products. How can you deal with that kind of stupidity? The guy obviously knew nothing about REAL quality. DEALERS told me that often these Jet grinders do not work straight out of the box!

Finally,I got them to agree to send me a new $2.75 circuit board. When I took the grinder open,I discovered that the push on connecters were LITERALLY as thin as beer cans. When the assemblers push them on,the connecters crack,and soon stop conducting electricity. So,I soldered the cracked connecter,and the grinder worked again-for a few more hours. Then it quit again. Before I got around to opening the blasted thing again,a friend gave me a Tormek wet wheel grinder. The Jet just sits there,taking up space. I might salvage the wet wheel off of it,but i'm tired of fooling with the stupid thing.

Years ago I had a Jet metal lathe whose motor stopped working. This was in the 80's. They could not take a VISA card over the phone. The parts guy was a real jerk. Very bad attitude. No help to the customer at all. I made the mistake of sending a check to Seattle from Va.. It took me 19 days to get the $2.00 part that they soaked me $20.00 for. I vowed I'd NEVER buy a Jet again. Then,I made the mistake of buying that grinder. Truly,I AM DONE with them!!!!!!!!

[david privett]

do you remember how far the shaft was out before being trued?

[Jim Underwood]

Never did check it. The rotor was scraping the coil laminations (only under power) and obviously (to the eye) the runout on the pulley shaft was out of acceptable range.. When I put the whole shaft between centers (after disassembly) the runout was less (by eye), but still unacceptable. When I put the case end caps on the bearings (without the case) and clamped the end housings in my workmate and spun the thing by hand it was still unacceptable. I can't remember if it was less or more and can't verify that because I measured nothing.
I suspect it's right back to where I was when I started out...

I'll try to post the video sometime today...

[Jim Underwood]

Here's a video I shot of the pulleys after first putting the motor back on. The only tension on the pulley is what the weight of the motor put on it. I first ran it up with the EVS, and you can hear the "scrape, scrape" noise at very low speed. It tends to diminish as the speed goes up. At the end of the video you can see I turned it by hand, and there's no more "scrape" noise. After I made the video, I removed the belt from the pulley and removed the chuck (which you can hear making a small "clack, clack" noise) and ran the thing under power- still makes the same "scrape, scrape" noise.

I suppose I could make a video (without belts on) that backs off of the opening so you can hear and see where the noise is coming from.


https://www.youtube.com/watch?v=UNFz7tq2sK8

[Dwight Rutherford]

Jim,
When I attempted to watch the video, I got a message " This video is private"

[Jim Underwood]

Try it now. I turned off the privacy setting.

[david privett]

you might want to try a mechanics stethoscope to isolate the rub .have you operated the lathe with the belt off?

[Dave Cullen]

The wobble in that shaft is way more than half a thousandth. This really bites.

At this point I think I'd be looking to replace the motor one way or another. You said it's not a standard NEMA frame -- have you looked at metric motors? Maybe it's a standard size somewhere else in the world?

[Joe Kaufman]

Did the motor shop perform electrical test on the stator such as coil resistance, Hi Pot or resistance to ground?
Possible short between windings?

With the motor running at the slowest speed can you increase the noise level by adding pressure to the belt?

Is the Stator assembly tight in the can/motor housing?

Possible open in one of the rotor internal shorting bars?

What is the approximate shaft size of the rotor between the bearings?

joe

[Wade Lippman]

what was strange was the 2 hp motor had 5 year warranty and the 1 1/2 hp motor had 1 year warranty......and the problem seems to be coming form the 2 hp motor

I hate to say it, but that's a relief... is it the 2hp motor that goes bad? I debated what to get and cheaped out on the 1.5hp.