Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: retro-AC-Servo on December 04, 2010, 02:26:29 PM
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So, First of all, Hi everyone!
Green Horn Here.
I just finished a retrofit of a Anilam knee mill.
I used the 4 axix AC servo Kit from Dmm Technologies.
Peak 7.2Nm(1015 OZ-In) high torque AC servo motor, 3 Axis CNC kit for MACH3
Here's some specs:
- 3 x Peak 7.2Nm(1015 Oz-In), rated 2.9Nm(408 Oz-In), Peak power 900W, AC servo motors
- 3 x Dyn2-H AC servo drives for very smooth,quiet,very high efficient driving
- 1 x DMB4250-8B breakout board, fully buffered Opto-isolated I/O, isolated PWM analog output
for spindle speed control,and charge pump. Hardware generated X secondary X' for CNC Gantry with
jump selectable motor turning direction.
- 1 x 6ft DB25 parallel port cable
- 1 x 6ft USB cable
- 2 x 120 or 220Vac input, 350w,+48Vdc, 7.3A output DC power supply
- 3 x 1ft cables between breakout board and drives
- 3 x 10ft differential signal encoder extension cable
- 3 x inductive, non contact , LED indicated proximity Home/Limit Switches
- 1 x Emergency STOP Switch
- Necessary Cables, DMM software for tune up servo
http://www.dmm-tech.com/Products.html
I have everything working good....Except one glitch... Randomly on long runs when the x axis is traversing it will stall or freeze for a 1/4 second or so, suddenly and abruptly. When it continues its motion it causes the axis to loose its position. I've checked the PC to make sure nothing is running in the back ground. I've changed the driver. I've checked for loose wires. I don't know where to go from here so any help will greatly be appreciated.
Thanks
Steve
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Check your sensor, I just retrofitted a machine with these and had a bad one.
If they are NPN NO type, you should have 12v open (24V supply) and <1volt closed.
The voltage should not wander,(my bad one wandered between 2v - 4v open)
please not that the light on mine worked right, but I had random events.
You can get these on Ebay for about $8, direct from China.
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Check your sensor, I just retrofitted a machine with these and had a bad one.
If they are NPN NO type, you should have 12v open (24V supply) and <1volt closed.
The voltage should not wander,(my bad one wandered between 2v - 4v open)
please not that the light on mine worked right, but I had random events.
You can get these on Ebay for about $8, direct from China.
I,m not quite sure what you mean by sensor.
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The Blue proximity sensor, check between the blue and black wires with a multimeter set on dc volts
what is your power supply voltage on the sensors?
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iF it were a limit switch activating it would stop mach as a limit trip. Check the mach driver test and look for something causing a pause in mach.
Just a thought(;-) TP
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BR549 is probably right, my sensors are wired into the amp. I do not know how fast Mach3 would trip on
one of them. These sensors do not go out often, and I would not have suggested it except that I seen
your sensors are the same as the ones as I put on my last machine. The test I suggested will rule them out
at least. I still have have the bad one, I think I will wire it into mach just to see what will happen.
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Well,
I disconnected the limit switch and it ran flawlessly all day.
When I set up the machine I didn't use the blue limit switch s in my set up since my machine was already set up with mechanical switches. I did notice when I disconected the wires at the breakout board one seem like it might have been loose. I should have been a little more careful because that might have been the culprit.
Anyway
Thanks Everyone!
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iF it were a limit switch activating it would stop mach as a limit trip. Check the mach driver test and look for something causing a pause in mach.
Just a thought(;-) TP
Well now it pauses in The Y axis as well. I ran the driver test. The first time I ran it it said pulse too slow in Red. is that normal? Is there some where where I can read or find information on how to use the driver test? I'm really not even sure of what the driver test is doing.
Steve
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You need to male sure Mach is shut down when you run the driver test or you will not get a true reading. The important thing in the driver test is that the graph looks smooth with no big spikes.
Hood
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So when it counts down to "Mach 3 taking over" and you see a initial spike then clean after a second or two. is that ok?
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That should be ok.
What kernel are you running?
Does the Frequency on the Diagnostics page sit steady at or close to the frequency your kernel is at?
Hood
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Yes it's close,
On the motor tuning and set up page there a setting for "step pulse" 1-5 and "dir" 0-5. Out of desperation I decided to tweek the "step pulse". Mine was originally set to "0" I changed it to 1. My problem hasn't re-occurred since I changed it. What might have I done? Keeping my fingers crossed... ::)
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That could well be the problem.
What frequency are you running the kernel at?
Hood
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Out of desperation I decided to tweek the "step pulse". Mine was originally set to "0" I changed it to 1.
Mach likes to put out little teeny tiny step pulses. Since the parallel port driver timing and hardware vary so much this can lead to pulses that are missing or way to short for the stepper drive to 'see'. Often times this problem presents itself as a 'tick' sound in the axis. Lengthening the step pulse or selecting the 'Sherline 1/2 pulse mode' are two ways to force Mach to increase the pulse length giving a better chance for a good pulse to be generated.
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Building on what Jeff said, you may want to look at your drive information as sometimes there is a recomended min setting.
RICH
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Well it ran great again all day today ;D. I'm cutting grooves in aluminum. My feed rate is set at 55 ipm and my program is about a hour long. So theres plenty of time for it to screw up.. I'd like to turn up my feed rate and see what happens. Maybe I'll get brave tomorrow.
Hood, its set at 25000 Hz
Thanks again for all the input.
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Thats fine, I was thinking you maybe had the kernel cranked up more than you needed. Its human nature to see that you can set it to 100KHz and think that must be the best but often it makes things worse. Obviously in your case thats not true so looks like the pulse width was the issue for you.
Hood