Topics

1

CS-Lab / PID Tuning, one axis perfect, the other causing a headache.

« on: July 21, 2016, 02:32:06 PM »

A brief background,
I've started another thread talking about retro fitting a ROMI lathe with mach3 , which had Bridgeport EZ PATH on. I've used a CSMIO A type to drive the existing hardware, brushed DC servo motors with encoder feedback going straight to the CS module.
Last night I very quickly tuned the Z axis which is being driven off the existing servo amplifier 100v DC. Smooth, no hunting, repeats accurately, everything is great.
Today I received a new servo drive for the X axis as the old amp died. It's an Axor MCS 110 6/12amp.
After wiring it in I'm struggling with the tuning config. After auto tuning several times the best I can achieve still leaves very slight ocilation/hunting and next to no rigidity. By that I mean I can twist the ballscrew pulley from 11 o'clock to 2 o'clock with little resistance. The motor screw ratio is 1:1.5, 6mm pitch b/screw, but it is a proven system from the previous control incarnation.

I thought the axis using the 20 year old servo card was going to be the issue, not this one with the modern drive!
Any suggestions greatly received.

2

General Mach Discussion / Novice to Mach3, may be asking too much??

« on: July 01, 2016, 05:37:57 PM »

I am a machine tool service engineer for a living, working on mainly FANUC controlled machines from 2 to 9 axis.
However at home I hoard machine tools from the turn of the century up to the 90's, which I use when commitments permit to build a scale model traction engine.
I'm at the stage now where I have a lot of parts to turn with radius's, tapers, fillets etc. I had begun to fit a hydraulic type copy attachment to my manual Colchester to produce these, when this happened...

I've been very lucky to aquire an absolutely mint 2 axis CNC lathe built by Brazian firm ROMI circa 1995. The cast iron itself is immaculate, however it is fitted with a Bridgeport EZ PATH control which has failed. Parts for the control are scarce and expensive ex USA.
A friend in Wales has been running a small stepper driven lathe with Mach 3 for years and swears by it, so I'm intrigued.
Can I source a solution to fit mach3 to my machine.
It has SEM 140v dc brushed motors
Electronic pulsed hand wheels.
Heidenhain rotary encoder for spindle speed feedback.
Could I integrate something that will drive these motors?
Could I use existing drive cards?

I would be great full for any help, advice or direction to research please.
EZ TRAK WAS THE MORE COMMON CONTROL VARIATION FITTED TO MANY TURRET MILLS. THE LATHES SEEM TO BE LESS COMMON. MY VERSION DOES NOT HAVE SPINDLE CONTROL.
THANKS.