Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: JobEwanKenobi on October 26, 2016, 12:24:57 PM
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Hey guys.. New member to the forums. Self Taught CNC...Built a Phlatprinter in my garage to build RC airplanes. Now I teach Laser and CNC at our local makerspace in North Little Rock Arkansas and I build high end Duck hunting boats on a 6x24 EZ Router running mach 3.
Having some issues with my router that I think are Mach 3 based and I am unable to get help from my machine tech support.
Put bluntly... My machine will suddenly start vibrating like it is demon possessed(Both during jobs or between jobs) and I will have an "External Estop requested" message at the bottom. If I click RESET... most of the time it goes away. Sometimes I will get a "Reconfiguration Estop" message. Sometimes I can bump a limit switch and it will kick off the Demon shakes... Sometimes if I close Mach3 I get the demon shakes..... and sometimes if I turn on the machine before Mach 3 is booted up.. the demon shakes ensue.
https://www.youtube.com/watch?v=Ubk1HZzcY_Q (https://www.youtube.com/watch?v=Ubk1HZzcY_Q)
Above is a link to this behavior.. that happens on a regular occasion.. I have just started noting the global coordinates of my zeros before I start a job in case I have to restart the job to try to save material. Any suggestions would be welcome.
Jeremy
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Which axis is it that is doing the shaking ?
Is it the one with the slaved motors ?
Tweakie.
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sometimes if I turn on the machine before Mach 3 is booted up.. the demon shakes ensue.
Nothing to do with Mach in that case. And it sounds as though you have servo motors, not steppers.
Which axis?
Try reducing the gain on that servo driver. Or maybe retune that axis.
Or start checking the encoder wires to the servo driver - one might be loose.
Cheers
Roger
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looks to me like you have a massive EMI problem.
unless you have some sort of charge pump safety enabled you should NEVER start the machine before Mach or shut Mach down before the machine.
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Hi Stirling
you should NEVER start the machine before Mach or shut Mach down before the machine.
Ahhhh - that is not going to work too well for me. I have to start the machine first so that when Mach3 starts it can load the firmware into the ESS. And I shut Mach3 down first as well. OK, point taken to some extent: the BoBs do have a charge pump enabled by Mach3.
EMI? Could be, could be. If the drivers to the Dir lines go tristate, could be.
Cheers
Roger
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Hi Roger
You've cut the bit off the front about charge pumps when you quoted me and then said you have a bob with charge pump so I'm unsure what your point is.
EMI? Could be, could be. If the drivers to the Dir lines go tristate, could be.
I'm hoping you don't think it's only tri-state outputs that can be affected by EMI. Plus I'm not sure where tri-state outputs would have a place here. Tri-state outputs are used to connect multiple devices to a bus architecture.
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Which axis is it that is doing the shaking ?
Is it the one with the slaved motors ?
Tweakie.
Once the Demon shakes start, it does it on all 3..usually it will vibrate up on z until it hits the Limit switch.. and the other 2 just grumble around.
We have thought about EMI.. but there are no welders anywhere near me and the closest TIG welder is 60 ft away.
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FWIW,
The machine doesn't shake ( lets use the term vibration ) when nothing is turned on. When the motors are turned on the machine may vibrate.
So the machine is sensitive to a range of fundamental frequencies. The machine will vibrate if a fundamental or some harmonic is near the machine / some part of it is near it's natural frequency. Should things be just right the machine can go into resonance and that you would surely know.
So there are a mechanical considerations to this and from a machine point of view vibration is being induced by the motor system.
If you accept that fact then look at the motor system to eliminate the machines vibration problem.
Curing one axis provides solution for the other axes.
Consider.........
What are the motors doing when just turned on but the controlling software is not providing servo control?
What happens when the servos are getting control instructions?
Noise / EMI can be seen as the equivalent to receiving software instructions.
Here a link to info on EMI:
http://www.machsupport.com/forum/index.php/topic,25616.0.html
RICH
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Hi Stirling
You are right: I should have included the full sentence. I abbreviated a bit too much. Charge pumps are 'good' until they are not good, which can happen.
Now the bit about tristate outputs. Yes, they are meant for driving common buses, but some BoBs use tristate devices as 'output drivers' on BoBs because they do have a good output current rating. That can mean that an output 'pin' will have a quite high impedance when the tristate chip is not enabled, so the line it is driving will be quite susceptible to picking up noise. Feed noise into a servo driver and all sorts of bad things can happen. So if Mach is not running the charge pump is not running so the tristate outputs are not enabled, so the sort of problems the OP described can happen.
Cheers
Roger
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servos (on a router that's advertised as having steppers), bobs with un-enabled tri-state outputs, seems like a lot of guesswork Roger. Perhaps the OP could confirm both/either? Me - I've got my buck on the TIG - but that would be a guess too to be fair ;)
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Hi Stirling
Yeah, lotsa guesswork. Sometimes we have to guess!
The Homann Designs MB-02 BoB uses tristate chips for some of its I/O pins. The tristate pin is usually driven by the charge-pump detector. I have two of them.
The TIG may well be the source of the noise all right, but it has to get into the drivers somehow. Steppers or servos - both can pick up noise on the Step/Dir lines. Yep, a guess. A starting point?
Cheers
Roger