Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: wawatobi on October 21, 2006, 12:30:37 PM
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I recently upgraded my Taig mill with their new DSLS system. I am having problems with the machine shutting down in the middle of jobs with unprogrammed e-stops.
This is very frustrating because I have to reinitialise each time this happens. I tried using a debounce of 5000 as suggested but I'm still having the problem. I
have to run below 25% of max speed to avoid these stops. I do not have the problem when moving at high speed while manually jogging the axes. Also, I am only
cutting wax. Anybody have any ideas?
Thanks, Wawatobi
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You have noise in your system and it could be a ground loop :( put on a low pass filter and it may fix your problem... What are you dunning for drives an so on?
Tho other thing that you can do for a test is to disable to Estop input. please have the power cable in your hand to power the thing down if you need to.
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Sorry, I don't know what a low pass filter is, and Idon't know what you mean by "What are you dunning for drives and so on?"
I'll try disabling the e-stop input and see what happens.
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I think "dunning" should be running :) Basically Brian is asking what make drives, breakout motors etc you have.
Hood
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Hi,,
I'm using Taigs new dsls 3000 servo system. Mach 3 post processor, Deskproto and BobCad to generate G-code. I can move the axes at blistering speeds
while jogging with no problem so far. Problem occurs when operating above 25% of Max during program milling.
Thanks, Rob
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Sounds like noise. Its about the only thing that will give you Estops when none exist. Set a
Debounce interval of 5000 in the config. That woudl be 5000 x 40us of filetering to stop the noise or about
200ms..
Art
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Tried debounce of 5000. Still get the e-stop
Wawatobi
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Setting the debounce to 5000 didn't help. I tried to deactivate the estop input but couldn't do it.
What is the proper procedure for this?. I went into ports and Pins, Input. Then changed the chekk mark on estop to an x, pressed Apply and then
OK. When I went back in, the check mark was in there again.
I tried moving the controller box but things got even worse. At the new position I couldn't even jog without the estop coming on. I moved the box
back where it had been before and things improved. Now however, the program estops even at 20% of max.
Wawatobi
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I tried running through a milling operation tonight and after a number of cycles I noticed that the estop always occured when the program called
for a z-axis movement. I took the z-axis motor off and reattached it . There are four pieces of plastic tubing between the couplings which link the motor to the
screw. The gap between the couplings was larger than the gap on the other two axes. I readjusted the gap to specs, cleaned the screw and tried running through
the milling operation again. I tried it at 20%,30%,40% and 50% of max speed and had no e-stop. My manual says that the program will e-stop if the encoder
doesn't match the motor input. I'm hoping that the crap on the z screw created enough drag to cause this e-stop. This has caused me a lost week of work so
I'll let you know if the problem is solved after runining the mill for a couple of days without problems.
Cheers, Wawatobi
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That is good to know! I didn't know that they did that... Every day my head gets more crap pushed in... It hurts...
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The saga continues. After cleaning and adjusting the mill I had a couple of hours of no E-stops. Then.... It started again. I'm losing a Thousand
dollars a week with the problems I'm having so If I've sounded a little screwed up, you're not imagining it.
I decided to call Kurt Daley of Microproto Systems. He called me right back. He claims that there is a problem with the way Mach 3 handles
backlash compensation. He said that if I turned off the backlash compensation, the e-stops would probably cease. He also suggested that if I had to
use backlash compensation then I should set the "backlash speed % of Max" to 200. I bit the bullet and tighened the nuts to reduce the backlash
to 0.001 on both the x and Y axes then milled for three hours without the backlash compensation on. No estops!!!. Today I recalculated the Backlash and turned the
backlash compensation on. I ran the mill for 10 hours today. I had an estop on the first job but I was running 60% of Max which is too fast for the job I was
doing anyway. I reduced to 35% of max which is what I usually run at when using the 4th axis and had no problem the rest of the day. Too early to say
if I'm back in business but I'll repost in a week or so if I have no problems. Baby, when this servo system works, my backlog gets eaten up in a hurry!!!
Wawatobi
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The Backlash is doing it????? you need to tell me more about how they think it needs to be done :)
Thanks
Brian
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Sounds like you are having a servo drive fault problem not an ESTOP problem.
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I'm sorry I can't answer any technical questions about this problem. I'm just a goldsmith trying to make a living the easiest way I can. The
manufacturer of my hardware says there is a software glitch in the way Mach 3 deals with backlash compensation. I've run my mill another
twelve hours today following his advice and haven't had any unwanted e-stops. I won't be satisfied until I've gone a week or so without
problems but so far his advice has panned out.
If my problem is noise , or a ground loop then why was I able to run my new system without a problem for several weeks before I started having
problems? I haven't changed anything except the software. Two weeks ago I realised that I had entered the backlash compensation corrections
but had't checked the box which enables it. When I realised this I entered 20% for the backlash compensation % of max. When I talked to
kurt Daley of microproto Systems about the problem he said that I either had to turn off the backlash compensation or use a % value of 200.
When I followed his advice I was back in business. Kurt said that Artsoft was working on the problem. That's all I know about this.
Cheers,
Wawatobi
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Wawatobi,
I have trouble with backlash comp. also. Mine does not throw an E-stop as I'm running steppers with no encoders. I think mine is because the steppers just don't have enough power to make such a sudden and fast change. Especially in CV mode on a radius. It skips steps. For you this would = a fault. I'm all but certain this is my problem. If I slow the feed rate to 50% the problem goes away.
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Backlash is a problem, period. I personally think art should just remove it. It is very rare that a system can use it. It isn't art's fault. when you really sit down and think about what backlash correction is doing the problems become obvious. 95% of stepper systems are going to choke on backlash compensation. I have tried it on two servo systems and also have problems with it.
When I first started with my first cnc retro it took me forever to figure out why my motors were locking up. Then I traced it down to backlash and I like others felt that mach had a bug. After working out what was happening I realized the inherent limitations of backlash compensation.
OK so where does this leave us? The best thing to do about backlash is get rid of it in the machine. No amount of software is going to fix it. When you are cutting the bit will pull the work into it because of the mechanical backlash and this is something that the computer cannot fix.
Backlash will absolutely not work in constant velocity, it HAS to be run in exact stop mode.
Wawatobi, I think the problem you are having is related to you feed back from the steppers and using back lash. From what i can gather if your stepper feed back realizes that you aren't where you should be it triggers an estop. When using backlash with steppers it is usually described as steppers stalling ( a common occurrence with back lash ) with your stepper position monitoring system it is bound to trigger an error and halt your code.
It is no ones fault, it just is what it is.
Chad
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I used my old Dos based Microproto stepper system for four and a half years without any backlash compensation problems. The new servo system has been
working for roughly 32 hours now without problem since I made the changes mentioned below. I don't have a problem with the cutter pulling into the work
because I'm only cutting wax. If I didn't have backlash compensation I would have major problems doing two sided milling. I always use meander as a cutting strategy because to cut conventional or climbing wastes too much time as the cutter picks up at the end of a run and goes all the way back to the beginning of the next line to start the next
cut. Imight be able to avoid backlash compensation for two sided milling by cutting in one direction for the top and the opposite for the bottom. I might try this after Christmas to see what happens. I believe it would take too long though.
Cheers
Wawatobi
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I have the same problem, the e-stop in the middle of the job. Sometimes it will go 2 or 3 minutes, then 15 or 16 minutes, so forth. After checking the history,below the Reset button, it would always stop after the comment "Too Fast For Pulley..using Max. The problem is, I have a CNC Router with direct drive, no pulleys. In the spindle pulley setup under the config tab, I tried various settings on the max speed, setting it very high (30,000 rpm) to Zero. Increasing it to the higher number increased the time before shutdown to about 25 to 30 minutes. I'm still working on the problem. I hope I can figure it out before I pull all my hair out. If anybody has any other suggestions, I would appreciate it.
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I posted this thread a couple of years ago. In the end I just turned off the backlash compensation. That pretty much ended the e-stop problem. I usually run at 40% of max and seldom have a problem. When I'm doing two sided milling, I move the quill by the amount of the backlash.
cheers, Wawatobir
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Hi, Garylmast
Have you tried un-checking "Use WatchDogs", In config, General Config, Usually gives a Watch-Dog error warning though.
Just a Thought, Chip