Jet 1642 losing power

[Kevin Bierman]

I have a 8-10 year 1 1/2 hp Jet 1642 I lent it to a buddy when I was on vacation and had not used it very much, doing flat work for Christmas, and have started turning again. The lathe runs fine, gets up to speed ok, but when I put a tool to a piece of wet wood I can stop it very easily. Checked the belt, it is tight does not slip. Found out my buddy tried to use it in his garage with GFI plug ins, that didn't work and I think he might have messed with the inverter, he wouldn't fess up. I talked to Jet service dept. and they want me standing next to it when I call, work days so having a hard time making that go. I did take the motor in, it checked out fine. Any one have an idea?

[Steve Schlumpf]

Kevin - do you still have the manual for the VDF? If so, check on how to do a reset. I have the 220 volt version and my manual says to just press the reset button after a fault to reset the VFD. Might be as simple as that...

[Len Mullin]

Kevin, have you learned anything from this experience? Personally, I'd never loan my lathe to anyone. I worked to long and hard to get the funds to buy it, you want to use one, buy your own. Granted I will allow people use my lathe, but, they have to use it in my shop while I'm present. If I'm not there, no one uses any of my equipment. Think long and hard before lending it again, that might help prevent these types of problems from happening.
Len

[Don Palese]

Hi Kevin,
When I had my 1.5 hp - 1642 -- I had a similar situation .. I don't think this is common at all and I really don't understand it .. but it seem the circuit break was going bad and when more load was calling on more juice .. it would just never recover until I stopped the machine and pressed the reset on the VFD. (no more demand on the breaker) I replaced the breaker with a new one and never had the problem again. I really would have preferred to have the breaker just totally fail. I sent it to GE the manufacturer but never heard back.

[Kevin Bierman]

Thanks for your replies, as far as loaning out tools, yeah it does seem like no good deed goes unpunished. I guess it is just in my nature not to say no to someone in need. some day I will learn. The lathe is the only big tool on that circuit so think I will try a different circuit before I get the manual out and start messing with the settings in the VDF. Thanks again will press forward, Kevin

[Dan Hintz]

Kevin, have you learned anything from this experience?

Who says his buddy was the one who broke it? Things do fail on their own...

[Bill Boehme]

Who says his buddy was the one who broke it? ....

You borrowed it?

[Dan Hintz]

You borrowed it?

I'll never tell!

[Dick Strauss]

Does Jet lock the VFD settings like they do for PMs? If so, your buddy would have a hard time changing settings unless he found the unlock code online.

[Kevin Bierman]

Dick..... I would have thought the same thing but when I talked to Jet service they didn't seem to think it couldn't be done. I really hope it is just a weak circuit breaker. Will get to play with it this weekend. Kevin

[Bill Boehme]

Here is one possible scenario for decreased motor performance when driven by an inverter. The PWM waveform that inverters use to synthesize sinusoidal output results in very large voltage spikes that can be well in excess of a kilovolt. That is why it is strongly recommended that motors rated for inverter duty be used. Generally, that means motors that have windings that have an insulation class rating of F, G, or H. It would be a concern if the motor insulation class isn't rated for inverter duty.

The problem often shows up as gradually decreasing motor performance that may stretch over many months which makes it harder to notice than a sudden failure. The cause of the failure is that the high voltage spikes penetrates through the insulation of the field windings usually where the wires make a sharp bend at the ends of the lamination stack. When this happens, the breakdown in insulation occurs between adjacent wires so the decrease in performance is slight. The problem is that there is an avalanche effect because each insulation breakdown puts an increasing load on the motor to maintain speed and torque.

Because these insulation breakdowns are typically microscopic, a visual examination probably won't reveal anything. I hope that your problem is something else.

[John K Jordan]

Pardon the simplistic question, but could your buddy have switched the belt to the high-speed position, reducing the torque?

If you want to check the VFD parameters and can't find them, send me a note by email and I'll send them to you. The first thing I did when I got my 1642 lathe was step through every parameter and write the values in my VFD manual.

BTW, if you don't have one the Delta Electronics VFD manual is available online as a PDF file. It won't have the Jet 1642 parameters though.

JKJ

[Bill Boehme]

Pardon the simplistic question, but could your buddy have switched the belt to the high-speed position, reducing the torque? ....

But, can't we run Kevin through the wringer a couple times before checking for more obvious things?

[Dick Bernard]

I have a Jet 1642, the 1 1/2 hp. Please be advised that I know "nothing" about electricity and/or electronics.
My question is, why is that VDF needed and more importantly, why are there different settings or, what would you use the different settings for or, when would you change the settings?

Is there a common setting?
As an example, could Joe in Montana use setting 4 (as an example) as well as Jim in Florida???

Thank you
Dick

[Josh Bowman]

Dick Not to get off topic with Kevin's question. But to answer your question, there are maybe 3 ways to control speed of a motor, belts and lots of pulleys, reeve drive (mechanical split pulley), VFD (Variable Frequency Drive) converts the incoming AC to DC and in the case of the Jet converts it back to a 3 phase signal that can vary the frequency, thus the speed.

Kevin, I'm with John Jordan, check if the belt is on the high speed pulley and tight. Let us know what you find.

I have a Jet 1642, the 1 1/2 hp. Please be advised that I know "nothing" about electricity and/or electronics.
My question is, why is that VDF needed and more importantly, why are there different settings or, what would you use the different settings for or, when would you change the settings?

Is there a common setting?
As an example, could Joe in Montana use setting 4 (as an example) as well as Jim in Florida???

Thank you
Dick