Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: fdos on April 14, 2006, 02:48:50 PM
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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.
(http://homepage.ntlworld.com/fdosdesign/temp/DSCF0336.JPG)
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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?
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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.
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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....
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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..
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Really cool, you can't mistake the scream of steppers...
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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...