Jet Mini Lathe Electronics

This group has -- time and time again -- been an incredible resource for problem-solving, so I'll just throw this situation out there, hoping for help.

One of my students purchased a used Jet 10-14 variable speed mini-lathe. It runs okay, but the variable speed feature doesn't function. We've replaced the pedometer, checked for loose wires, and even taken it to an electronics repair shop. Jet says the mother board is no longer available. Short of removing the control box completely and simply using the change-a-belt system, I don't know where to send him.

Any ideas?

It's called a potentiometer. The generic control replacement is from Amazon. https://www.amazon.com/dp/B00RW7LSXM...v_ov_lig_dp_it
But just looked it up and not available now. But they have other controllers. Just make sure to match the DC voltage and HP capacity.

Russell,

Is there any labeling on the motor? From the limited info in the manual it looks like the motor might be a universal motor. If it is, a motor speed control of appropriate power rating, like those sold for routers, may be used to replace the existing control box.

I just replaced the potentiometer in my little Delta a month or two ago. The original "pot" was marked with the ohm size (50k if i recall correctly??) and got 3 for under $10 shipped USD. About a 10 minute job to change out. Cheap enough to be worth a try.
earl

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Originally Posted by Paul F Franklin

Russell,

Is there any labeling on the motor? From the limited info in the manual it looks like the motor might be a universal motor. If it is, a motor speed control of appropriate power rating, like those sold for routers, may be used to replace the existing control box.

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VS Jet lathe motors are DC motors, not universal.

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Originally Posted by Richard Coers

It's called a potentiometer....

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Understood. Funny thing is there's an expanded parts list in the manual that calls it a "pedometer."

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Originally Posted by Russell Neyman

Understood. Funny thing is there's an expanded parts list in the manual that calls it a "pedometer."

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Funny is right, a pedometer is a device to measure walking footsteps.

Russell, could you have your student measure the voltage that is going to the motor. Or perhaps there is a plate on the motor that states the voltage?

From your description, it would appear that the DC power supply is working in a "full-on" mode. I may be able to suggest something to easily fix the problem, but I need to know the voltage going to the motor. (BTW, I'm a degreed electronic engineer).

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Originally Posted by Brice Rogers

Russell, could you have your student measure the voltage that is going to the motor. Or perhaps there is a plate on the motor that states the voltage?

From your description, it would appear that the DC power supply is working in a "full-on" mode. I may be able to suggest something to easily fix the problem, but I need to know the voltage going to the motor. (BTW, I'm a degreed electronic engineer).

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Here is a picture of the name plate on my 10-14VS.
Attachment 481246

Penn State Industries sells a variable speed conversion kit for the lathe. May be able to use the controller parts from that kit? May also be worth a look.

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Originally Posted by Richard Coers

Here is a picture of the name plate on my 10-14VS.
Attachment 481246

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Thanks for posting, Richard. I am aware of some 1200 watt DC speed controls that use pulse width modulation that are really inexpensive. But, unfortunately while they can handle the power and current draw, they aren't rated to the 162 volts on your nameplate. So, they won't work without some modification.

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Originally Posted by Kyle Iwamoto

Penn State Industries sells a variable speed conversion kit for the lathe. May be able to use the controller parts from that kit? May also be worth a look.

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I have yet to find someone that really likes that kit for anything more than turning pens.

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Originally Posted by Brice Rogers

Thanks for posting, Richard. I am aware of some 1200 watt DC speed controls that use pulse width modulation that are really inexpensive. But, unfortunately while they can handle the power and current draw, they aren't rated to the 162 volts on your nameplate. So, they won't work without some modification.

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Do you think this controller would work for him? https://www.ebay.com/itm/120-VAC-To-...-/303159304376

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Originally Posted by Richard Coers

I have yet to find someone that really likes that kit for anything more than turning pens.

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Yes you are right, but the controller parts may work.
But then the Jet mini is not a heavy duty powerful lathe to begin with. I think hands down the best pen turning lathe for the money. I have 2 of them.
Just my $0.02.

Richard Coers, yes, it would probably work.

I noted on the specs that it says: "Simple wiring to 95-135 Volt Permanent Magnet or treadmill DC motors (up to 21 Amps (1-3 HP)).

For Permanent Magnet DC motors with 2 wire (Red & Black or White & Black) hookups."

So, if the motor on the lathe is a 2 wire, it should run. It seems to have enough power to run the lathe motor. The only thing I'm uncertain of is whether it could provide a high enough voltage to drive the motor to its full speed. I noted on the picture that you posted that the voltage (max or operating?) is 162 volts. And the replacement controller states 95v to 135v. But, I suspect that it probably would work.

If the original poster could measure the voltage to the motor (which apparently is currently running at full speed) and if it is close to the 95-135 vdc, then it would work. Perhaps the 162 vdc is a max rating and isn't the normal operating voltage?? But the original poster would be working with potentially lethal voltages and shouldn't attempt to do that if they are unfamiliar with dangerous voltages and don't know how to do it safely.