***Resolved*** NEW PM-1440HVT-2 Lathe (PM fixed it)

[DavidR8]

So in neutral the belts and motor run perfectly smooth at full speed. I checked the tension of the belt and it felt fine. Seems like if it was the belt being too loose I'd get some slippage even at low speeds when i'm turning something lets say aggressively and I've never had any issues with speeds 0-300.

Ok if in neutral it runs fine through the full frequency range but will not when the spindle is engaged then to me it has to be related to the drivetrain that is in motion unless some parameter or issue in the VFD causes it motor to buck and stall like that.
@mksj have you ever seen a vfd powered motor do that?

 

[tim81]

Ok if in neutral it runs fine through the full frequency range but will not when the spindle is engaged then to me it has to be related to the drivetrain that is in motion unless some parameter or issue in the VFD causes it motor to buck and stall like that.
@mksj have you ever seen a vfd powered motor do that?

We had a wood cutter with flat belt it would skip and vibrate when not tensioned properly and the cutter was rigged up machine as we were poor in southeast Europe. Now here on the 3d printer with timing belt if I run it high speed without proper tensioning it will jump. It looks like you case and it matches the sound to a certain point.

 

[yarm2111]

Did you try it in reverse?

 

[mksj]

The problems I have seen with VFD's is cogging of the motor which did not occur at a particular resonant frequency as he is seeing. Sometimes there is an improvement with doing an Auto-tune, but this looks more like a machine resonant frequency issue. The motor/belts are smooth when in neutral, so it is only occurring when the spindle is engaged. As mentioned I would try to tension up the belts, they are moving way too much and occur at the resonant frequency. I would also considering measuring them and replacing them with a pair of Gates Tri-Power cogged belts. The other thing I would recommend trying is put the 3J or 4J chuck on the spindle and see if that changes anything, as the flywheel effect should smooth the oscillation. With a resonant point the machine should run smoothly above and below the resonant frequency, if it is a mechanical issue I would expect it to get worse with higher speed.

 

[tim81]

The problems I have seen with VFD's is cogging of the motor which did not occur at a particular resonant frequency as he is seeing. Sometimes there is an improvement with doing an Auto-tune, but this looks more like a machine resonant frequency issue. The motor/belts are smooth when in neutral, so it is only occurring when the spindle is engaged. As mentioned I would try to tension up the belts, they are moving way too much and occur at the resonant frequency. I would also considering measuring them and replacing them with a pair of Gates Tri-Power cogged belts. The other thing I would recommend trying is put the 3J or 4J chuck on the spindle and see if that changes anything, as the flywheel effect should smooth the oscillation. With a resonant point the machine should run smoothly above and below the resonant frequency, if it is a mechanical issue I would expect it to get worse with higher speed.

I was paying attention to his video with his belt while it was doing the noise and I noticed the belt jumping left and right way too much. If it was the motor the belt would not move left and right that much as the noise would be internal to the motor I think.

 

[davidpbest]

Just reading through this thread for the first time. I feel your pain. Been there with my PM-935 which ultimately required a full J-head replacement to fix my issues. The back-and-forth with PM in diagnosing the issue, trying various part replacements from the factory, and trying all kinds of "hail Mary" suggestions from PM went on for the better part of 3 months. That saga is documented here if anyone cares to see. That said, Matt will get this fixed for you, but it will probably take time and a lot of effort on your part.

Viewing the videos you made, and reading all you have done, I'll put $20 on the idea that this has nothing to do with the VFD and is a loose gear or missing snap ring or other mechanical issue within the headstock. Who wants to take my bet?

 

[tim81]

What makes me a bit question is why the belt oscillates at the time it makes the noise. It looks like it is enough to skip a tooth and that would qualify as a noise and cause the belt to rattle

 

[7milesup]

What makes me a bit question is why the belt oscillates at the time it makes the noise. It looks like it is enough to skip a tooth and that would qualify as a noise and cause the belt to rattle

That is not a timing belt, which runs in corresponding teeth on a pulley. Those are cogged v-belts, which allow smoother power transmission due to reduced bending tension as the belt follows the radius of the pulley, but they do NOT run in teeth on the pulleys.
It does look like the tension could be increased slightly on them, but I highly doubt that they are the cause of the issue, but rather, part of a set of symptoms.

 

[tim81]

That is not a timing belt, which runs in corresponding teeth on a pulley. Those are cogged v-belts, which allow smoother power transmission due to reduced bending tension as the belt follows the radius of the pulley, but they do NOT run in teeth on the pulleys.
It does look like the tension could be increased slightly on them, but I highly doubt that they are the cause of the issue, but rather, part of a set of symptoms.

Let’s hope it’s the belt.

 

[paynerd]

I just saw a video they attached to my email and it showed them with a micrometer and how much play is in those gears and it looks to be good.

There's not a belt tensioner on this. It has that what I'd call an idler wheel that gives it the tension. I almost want to take your bet Mr. Best but I think you're a smarter man than I am. haha. PM seemed to jump all over the VDF so I almost wonder if its a known issue. Just seems strange to think its that but after messing around in there today it almost seemed like the noise was below the headstock. It's so hard to tell. Here's my thought. They want me to run some tests to rule out the VDF. If anyone can help me do that, it will speed the process up for getting them off the VDF wagon. Here is the picture and what they wanted me to do. I downloaded the users manual and I'd need to get another college degree to figure it out.

This was one of my first emails from PM-
I am working on this with the factory, and they want to make sure that it's not a standing wave resonance issue with the VFD and motor. I'm a little skeptical that this is the solution, but we will at least rule it out. They would like to adjust the parameters on the VFD in the following way. I will just copy exactly what they're instructions are.
Please set parameter F739 to 168 and F700 to 0. This way, you can unlock and have the access for changing the parameters.

Check and set the parameters
Pt = 5
vL= motor Hz
vLv = motor voltage V
F405 = motor Kw
F415 = motor current A
F417 = motor rpm

Make sure the above parameters are correct. Please reduce the parameter of F416 between 25 ~30. If it’s not working, please change the LL parameter to motor Hz. It’s important that you record the original value of LL before changing to motor Hz. Please turn the speed to slowest and then set the parameter of F400 to 2. Then, runs the machine for about 1 min. This way, the motor is re tuning. See if this works.

If it’s not working, please change the parameter of LL to the original value.
Let me know if that does or does not help.
Thanks!