PNC2c Lathe electronics/electrical diagrams

[Jon]

Hello,

I have taken ownership of a neglected lathe.

It seems that it started life in 1982 at a University and then its history is a bit vague. It has sat un-used for the last 9 years, I think the last owner may have had it working with an inverter for the main spindle and I suspect the joystick only controlling the x and z.

The left hand cabinet leg has a very scary decrepit bunch of wiring much of which is disconnected including two chunky capacitors and four smaller ones. There is also a disconnected 4 core cable - presuming at the moment that this is the motor power and the disconnected electrical thing - that is in no state to have electricity near it - is the original 3 phase inverter and speed control it really is looking grim with about 20years of workshop all over it.

The Coolant pump is 240V.

At the top on the left hand side seems to be a pair of stepper drivers and a PSU which appears to be powered by crazily thin cable - I am again presuming that this is 240VAC -> 48VDC. this all looks very clean and I am pretty sure I can guess which are the step and direction connections so it is tempting to try this module, but I would have to confirm there was no shorting in the stepper cabling... The fan on the top at the left was unplugged.

One of the PC boards has a nasty burn mark where it looks like power goes into the board. There are a suspicious number of things disconnected.

The main spindle turns very nicely, the belt is worn on one edge and I think the spindle sensor plate is slightly warped. the Z axis moves very nicely and the X seems ok.

There are a couple of predictable dings under the chuck and there is some nasty pitting under the tail stock that goes through the hardened layer but this looks like an easy fix with some filler product.

The exposed wiring is in a "shocking state", so I am very hesitant to use any of the electronics but the more I know the easier testing / re-wiring will be.

Unfortunately the lathe has also suffered some superficial damage in transport including the one shot oiler, some of the metal work at the top and some trim, various buttons are smashed. It is missing its QC toolpost. It would have been a lot nicer if it had ever been cleaned.

Mechanically the lathe seems ok so far so I think my best option is a new controller, stepper drivers & PSU, inverter for the spindle inc speed control. I have a milling machine using a dynomotion controller and I think that is my preferred route for this lathe as well.

Please advise if there are documents and or drawings for the PNC2c or if should just try to work from the PNC3 drawings? Are there any sections that will be identical or should that be "similar"

The motors specifications and wiring are the main part that I really want to know atm, I think restoring the old computer will have to wait for another day..

I am yet to lower it the last 4 inches onto its base - I am missing the adjustable feet... and wondering what they are supposed to be like it would be nice to make something similar before lowering it the last bit.. I just have circular holes not threaded and I cannot see anything resembling an adjustable foot in the PNC2 spare parts list document.

Thanks,

Jon

[Jon]

https://plus.google.com/photos/10072868 ... 9813054337

the above link should give you some idea of the sorry state of my lathe, I am responsible for making it look much worse by opening everything up.

I was quite concerned about where I could apply 240V without it going in several directions.. anyway having found the pin burnt out of the board on the NEE controller I have decided to shelve that for a rainy day.

So decision made new motion controller.

The PSU for the stepper controllers seems good - the z-axis stepper holds position, the x-axis was buzzing but I was not brave enough to reach in as there are plenty of frayed wires.

The stepper boards are quite awkward to extract and I don't want to if I don't have to the colour coding for the stepper wires is as per the EasiTurn3 electrical diagrams. There are 8 control wires coming from the NEE presumably +ve and +neg for step and direction for each axis.

I have not managed to identify the stepper driver boards, more reading to do I guess.

Next stop working out which wires provide step and direction and with what sort of signal.. Any clues welcome There is one green LED over three red.

What are the electrics that sit just over the spindle motor, seems to be yet another little transformer and separate to the spindle motor power cable?

Jon

[Jon]

make that 5 wires from the NEE to each of the stepper drivers.

[angel-tech]

stepper drives look like parker cd20

[Jon]

stepper drives look like parker cd20

Thanks I downloaded every driver manual I could find on here and found the parker manual matched up

The 5 wires (ribbon cable) from the NEE controller go to 5 consecutive pins as per page 6 https://www.denfordata.com/downloads/dos/cd20-30.pdf for each axis.

20 Fault
22 Zero Phase
24 Boost
26 Direction
28 Step

I presume that Zero Phase is where the digital 0V signal connects..

I cannot see what the purpose of the "boost" connection is? possibly something like half stepping?

The electrics over the spindle motor are as I thought independent of the 3 phase cable going to the motor, there is a 24V AC transformer, not certain what the other transformer is but looks similar.

cheers,

Jon

[Jon]

Couple more photos uploaded and questions below:

The armoured cable that housed the X axis stepper motor signals to the carriage was one of the shockingly scary bits, it had been continuously rubbing on the bed of the lathe, poor routing choice at some point..

The drive spindle drive belt is worn badly on one edge - it has been installed a groove out of position - again not clear if is original.

Can anyone give me the specification for the belt for ordering another? it will be easy enough to count the grooves but any tips on how to make an accurate length measurement would be appreciated.

The spindle motor is impressive running on a cheap inverter. I think I may have scared some grease out of the bearings, the front spindle bearing has a grease nipple, there does not seem to be a nipple for the rear bearing?? I am slightly embarrassed to admit how smooth the spindle is at double it's rated speed and no lack of grunt at low speeds.

My only frustration at the moment is that I have found a "spare" wavy spring washer that matches exactly the one in the end of the X axis stepper motor housing as a preload for the bearing there....the obvious conclusion is that there were two washers parallel and mating to increase this pressure can anyone confirm this? It is frustrating as it seems that the bearing is overkill anyway, so what difference can one washer make? and I can obviously check the Z axis motor... but it is a real pain and I cannot really replace the wiring anyway which is why i ripped the first one apart in the first place #messyworkshopproblem #selfinflicted

The step and direction logic signals for the parker stepper drives are 12v, but I doubt they are going to feature in the end solution.

One board member did contact me by PM and we had a conversation that was very helpful


Jon

[Jon]

Both axis alive see new video, happy days.

Now I need to re-instate the spindle sensors and some limit switches etc etc..

And work out how I am going to attach tools...