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View Full Version : Got a new (used) lathe....and already managed to let the smoke out



lbhsbz
12-17-2011, 06:57 PM
Picked up a Cadillac 1440G from a guy I know to replace my POS DarSin 1340....got it all unloaded, sort of leveled and decided to see if my 3hp RPC would run it....and it did for about a minute....until the smoke came out of the panel in the machine.

I guess it had some electrical problems that he had his guy "fix"...but it would seem as if they didn't get fixed.

It's got a 3 hp motor, that appears to be a single speed...any way to tell for sure?

The whole electrical box looks like a mess of wire nuts and 3 different brands of contactors, and there's an empty spot where it looks like another one was at some point.

Can tear all this stuff out and just run this thing off of a VFD? Program it for external inputs from the existing barrel switch and brake? I don't need the coolant pump, and if I ever do, I can find a 110V pump.

Tait
12-17-2011, 07:20 PM
I don't know about your specific lathe, but I'm running my little atlas 618 from a VFD. It works far better than the stock, dying, 1 speed 110V motor it came with. With the VFD, I don't have to stop to change pulleys, and can even jog reverse when I want to reverse out a tap - it works great for my needs.

If the motor is three phase, it should be able to run from a VFD. You might open it up and see if there's a wiring diagram.

crrmeyer
12-17-2011, 08:24 PM
The Cadillac (YAM) lathes had both single speed and dual speed motors. The dual speed motor was 3/5 HP (depending on speed). I suspect you can look at the number of wires coming from the motor to confirm 3 wires + ground would be a single speed motor. All the wiring diagrams I have seen only show wiring for the single speed motor.

Good Luck!

wierdscience
12-17-2011, 08:43 PM
Is the lathe single or dual voltage and did you check to see which one it was wired for?

Also if the lathe has 120v contactor control coils that tie to ground(possible since it's been into)you may have smoked the coils since the RPC is capable of higher than 120v to ground on the generated leg.

But ya,rip all that crap out and swap a VFD in there assuming it's single speed.If it is two speed you need two VFDs and some extra stuffing to go in that bird:cool:

lbhsbz
12-17-2011, 08:43 PM
Ok....it's a single speed motor, 3hp....fer sure.

I did some more playing with it and it still works in reverse, of course it would appear that a Japanese contactor is in place for reverse. The Taiwanese contactor, that I'm assuming is for forward, is a gonner. Even when I manually push in the button it just makes funny noises.

For the price of a 5 or 7 hp rpc and a new contactor, I'm thinking I might as well just get a 3hp VFC and i'll have variable speed instead of the 6 speed....most likely for a fraction of the price.

lakeside53
12-17-2011, 08:46 PM
You'll stilll need the gears - little torque at low speeds (less then 15-20hz) if not. The VFD should wire directly to the motor; rewire the lathe controls to the VFD low voltage inputs.

I use both Teco and Hitachi VFDs. I really like the Hitachi SJ200 and new WJ200 series.

hardtail
12-17-2011, 10:15 PM
Whats the third contactor for? Mechanical oil pump or electric?

lbhsbz
12-18-2011, 12:54 AM
It got an electric coolant pump. I'll post a picture in the morning...

Boostinjdm
12-18-2011, 04:52 AM
you may have smoked the coils since the RPC is capable of higher than 120v to ground on the generated leg.


That's how I smoked my work light. Good thing I didn't plan on using it anyway.

aboard_epsilon
12-18-2011, 08:07 AM
its his electrical box thats gone up in smoke ..he says its been messed with

maybe it had a neutral and the person who messed with it tried to get it working without

these contactors can burn ..sometimes cleaning the points can sort things out ..

sometimes they have a small transformer in the box that works the contacts ..others have the neutral wire

just thoughts and not necessarily good ones ..but may help to set you on the way to a solution .

all the best.markj

lbhsbz
12-18-2011, 07:50 PM
Smoke cam from in here. The one in the middle works, but no signs of life from the ones on the left and right. I think a vfd is the best solution. How well do they deal with high load starts?

http://img.photobucket.com/albums/v201/machschnelGTI/ee0746c9.jpg

hardtail
12-18-2011, 09:44 PM
They deal very well with it as you can set the ramp but it has to be sized properly, 3hp your probably at the top end of not worrying about derating but check with the manufacturer anyway.

You might have to come up with something else if you need coolant but it should run forward/reverse just fine.

EVguru
12-19-2011, 06:04 AM
I've seen that problem a few times!

Any control gear should be supplied from the 'genuine' phase, not one of the generated ones.