Also posted in the Yahoo forum)

Well this w/e I decided I was going to try and get the VMC running on
Mach3. 

Just about a week ago i tore out the Meldas Control, and decided because
the AC servo's were unsuitable due to a combination of being high
encoder count (5000lpr) and not being confident of find drives to suit
them , so they came out.

Couldn't find any Brushed servo's that would fit in the space (Y axis
only allows 230mm max motor.encoder length)

So back to  trusty steppers for a while  ;-)    After finding one of my
Parker OEM-650 drives would not step but would self test ok I thought
this was going to be a disaster of an easter w/e!

But carried on regardless just to see if I could get an axis moving.

Got the couplings made up and put a  34 frame 7Nm motor on X axis.

This motor would do just about 2200mm/min on the bench (10 microstep)
before stalling.

On the machine I was pleased to find with the compliant coupling and the
machine load I got 3600mm/min at 25Khz.

At 35Khz I can get 4500mm/min (177"/min) without any lost steps so far.

With a total of 350mm x travel thats pretty good. Not quite the 10m/min
the meldas and ac servos could do but pleasing  ;-)

Will try the motor on Z later (counterbalanced)

The G-Rex in a few weeks when I'm happy all 3 axis work well.

Now to get a couple more motors and another drive....

Wayne....

Here's pic of the machine before I tore out the control.

Could I ask, what pitch the ballscrews are in this machine, so as to compare to what my lathe might be capable of for feeds?

Could I ask, what pitch the ballscrews are in this machine, so as to compare to what my lathe might be capable of for feeds?

Ballscrews are 25mm dia x 5mm pitch (approx 5tpi)   Motors are coupled direct (no reduction) via spider type resiliant couplings.

The machine has multipoint lube (1 shot every 6 mins) and turcite ways.

Motors I am using are 7Nm with Parker OEM-650 drives at 75V 4A.

Update to my own msg.

Made adapters to fit the motor on Z.   Ran it for a few hours, no real problem and motor runs cool at 4A.

4200mm/min rapids.   Bumped current up to 5A (less than 4A x sqrt2 = 5.6A which is the most I would go) and monitoring motor/drive temps carefully.   I now get 5200mm/min rapids on Z (just over 200"/min)

Running a 50,000 line short line segment program with interspaced 200mm rapids here and there, and checking periodically a z zero on a  dial guage.  No problems yet!

 Just thought you might want to know it's not all about problems in here ;-)

Wayne....

for those remotely interested, is anyone really interested?   I have put a quick video of the machine running a peckdrill cycle under mach3 control on my homepage.   Direct link is;

Now availailble on MachSupport site.

Have fun..

Really cool, you can't mistake the scream of steppers...

Really cool, you can't mistake the scream of steppers...

For a while ;-)   When it's earned some new servo's it will have them.   Though it's not bad that I can achieve 50% of the orginal servo rapid speeds.  I'll tame it a little though just to be on the safe side.   Besides only the Z axis really has the length (14" travel) to get upto that speed.  Steppers just cant accelerate like the Ac servo's could.

Wayne...