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Powermatic 3520c Motor Noise

J

Jon Bricker

Joined
Apr 14, 2021
Messages
7
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0
Location
Parsonsburg MD
I just purchased a new Powermatic 3520C and noticed what sounds like a metal to metal motor noise at around 100 rpm. I called JPW tech service and the person said it was normal. Has anyone experienced this same problem? I have a Jet 1642 EVS 2hp and it is quiet at low rpm settings.
 
I have a new (last August) 3520C, and I have on occasion heard a repeating clicking kind of motor noise. At first I thought it was in a new chuck that I’m using, but yesterday I took the chuck off and still heard it. Lots of careful listening and feeling finally allowed me to find the culprit. I slightly eased off the belt tension and the sound went away.
 
I've got a 3520B.
Sometimes have heard a tick, tick, tick - that's usually a set screw loose on one of the pulleys. People also report loose set screws on the tach sensor. But that's not what you're describing.
Sometimes I hear something like swish, swish, swish - that seems to be dirt or something on the belt or pulley. But sometimes it does it when the belt is clean, I suspect it's just from slight changes in the belt tracking as it goes around.

If I heard a metal screech, I'd probably inspect the pulley set screws, see if one of the pulleys is slipping.

I've found noises from inside the headstock are sorta hard to locate. Maybe get a length of hose and use it like a "stethoscope" to maybe pinpoint the source?
 
Jon, I have a new PM 3520C and also a Jet 1640EVS. When I got the Jet1640 I heard a noise which I would describe as a brief gurgling sound that would only happen around 100 rpm and then quickly goes away as the lathe passes thru that RPM. I only hear it when stopping the lathe but not when running up the rpm for turning. I thought it was a motor problem but suspected that the sound had something to do with the braking of the motor. When I got my 3520C I heard the same sound although it is not as pronounced as it is on my Jet. As an experiment, I pulled the plug on my jet instead of hitting the off switch and let the motor coast to a stop. There was no gurgling sound. This seem to confirm that the gurgling sound has something to do with the motor braking. I also asked a Jet Tech and he also told me it was the braking. In my case, the sound is not very loud and it is very brief and only occurs when stopping the lathe. I've had my Jet 1640EVS for a little over 2 years and have not had any motor problems. Hope this helps.
 
Last edited:
Jerry Bochenek said:
Jon, I have a new PM 3520C and also a Jet 1640EVS. When I got the Jet1640 I heard a noise which I would describe as a brief gurgling sound that would only happen around 100 rpm on the belt is on the low pulley and then quickly go away as the lathe passed thru that RPM. I only heard it when stopping the lathe but not when running up the rpm for turning. I thought it was a motor problem but suspected that the sound had something to do with the braking of the motor. When I got my 3520C I heard the same sound although it is not as pronounced as it is on my Jet. As an experiment, I pulled the plug on my jet instead of hitting the off switch and as the motor coasted to a stop there was no gurgling sound. This confirmed in my mind that the gurgling sound has something to do with the motor braking. I also asked a Jet Tech and he also told me it was the braking. In my case, the sound is not very loud and it is very brief as it passes thru that low rpm of about 100 rpm when stopping the lathe. I've had my Jet 1640EVS for a little over 2 years and have not had any motor problems. Hope this helps.
Click to expand...
 
Lou Jacobs said:
I have a new (last August) 3520C, and I have on occasion heard a repeating clicking kind of motor noise. At first I thought it was in a new chuck that I’m using, but yesterday I took the chuck off and still heard it. Lots of careful listening and feeling finally allowed me to find the culprit. I slightly eased off the belt tension and the sound went away.
Click to expand...
Lou,
Thanks for the quick reply. I just tried the belt tensioner but no luck.
Thanks again,
Jon
 
Jerry Bochenek said:
Jon, I have a new PM 3520C and also a Jet 1640EVS. When I got the Jet1640 I heard a noise which I would describe as a brief gurgling sound that would only happen around 100 rpm on the belt is on the low pulley and then quickly go away as the lathe passed thru that RPM. I only heard it when stopping the lathe but not when running up the rpm for turning. I thought it was a motor problem but suspected that the sound had something to do with the braking of the motor. When I got my 3520C I heard the same sound although it is not as pronounced as it is on my Jet. As an experiment, I pulled the plug on my jet instead of hitting the off switch and as the motor coasted to a stop there was no gurgling sound. This confirmed in my mind that the gurgling sound has something to do with the motor braking. I also asked a Jet Tech and he also told me it was the braking. In my case, the sound is not very loud and it is very brief as it passes thru that low rpm of about 100 rpm when stopping the lathe. I've had my Jet 1640EVS for a little over 2 years and have not had any motor problems. Hope this helps.
Click to expand...
Jerry,
My motor issue sounds similar to yours but is a screeching sound when going from zero to around 100 rpm. Possibly a brake release problem.
Thanks,
Jon
 
Dave Landers said:
I've got a 3520B.
Sometimes have heard a tick, tick, tick - that's usually a set screw loose on one of the pulleys. People also report loose set screws on the tach sensor. But that's not what you're describing.
Sometimes I hear something like swish, swish, swish - that seems to be dirt or something on the belt or pulley. But sometimes it does it when the belt is clean, I suspect it's just from slight changes in the belt tracking as it goes around.

If I heard a metal screech, I'd probably inspect the pulley set screws, see if one of the pulleys is slipping.

I've found noises from inside the headstock are sorta hard to locate. Maybe get a length of hose and use it like a "stethoscope" to maybe pinpoint the source?
Click to expand...
Dave,
Thanks for your reply. The screeching seems to be emanating from the fan end of the motor. I’ll use your hose stethoscope method to investigate.
Jon
 
I am not familiar with the 3520, but if you have not already tried it, loosen the drive belt and see if the noise goes away when only the motor is turning.
 
Dennis,
Thanks for your reply. I have tried that with no luck. The low rpm screech is coming from the fan end of the motor so it may be a brake or armature problem. The lathe is new so I may return it to JPW.
Thanks again,
Jon
 
I chase a lot of subtle noises for my piano and organ work. Do yourself a favor and buy a $10 stethoscope and pull the end off so you just have a rubber hose end. Having the headset that hooks to your ears frees up a hand (because you're not holding one end of the hose in your ear) which makes it much easier to poke around and move things as needed to find the noise.
 
This hose/stethoscope technique is very interesting. Where exactly are you supposed to put the lathe end of the hose/stethoscope? Outside the headstock housing? How does using it outside localize the source through 1/4" of cast iron?
 
Backyard mechanics like myself take a long screwdriver and touch it to the offending part (a static part of course) while putting your ear to the handle. Works pretty good on machinery and even 500hp Porsche engines when in a pinch.

A stethoscope is best, but until you get your hands on one - try the screwdriver.
 
Dean Center said:
This hose/stethoscope technique is very interesting. Where exactly are you supposed to put the lathe end of the hose/stethoscope? Outside the headstock housing? How does using it outside localize the source through 1/4" of cast iron?
Click to expand...
You'd be amazed how well sound transmits through cast iron.. Literally you can hear a loose bearing inside an engine block of a running diesel, and then locate approximately where it is based on moving the stethscope (or wood handled screwdriver, touching the tip to the block) to different spots - where it seems loudest is closest point to the detector.. I am deaf so I actually fashioned an electronic stethscope using an automotive knock sensor hooked to a DSO (Digital Storage Oscilloscope) that worked on the same principles, except I could "see" the noise rather than hear it.. :)
 
A friend of mine was an army mechanic around -71 working with good old Centurion tanks.
He succesfully used a screwdriver for the spotting worn bearings, even with that level of noise and vibration.
 
I have had one like Clifton posted for 25 or 30 years--dig it out several times a year, and it's an invaluable tool for isolating where a noise is coming from. The ones i used as a medical first responder are much more sensitive (and expensive), but i think they might pick up too much noise for mechanical work.
earl
 
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