Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: dresda on September 08, 2009, 11:39:46 PM
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I do have a few questions: Is there anybody that has tuned Ac fanuc motors (red cap) using the PID. I can make them work, but I don't like just putting any # in and seeing what happens, well I know what happens, the motor jumps off the bench and almost breaks the encoder off. The motors don't hunt or vibrate and run good but sound loud when running, doesn't matter what values I put in, those Fanuc motors usually are as quiet as a mouse when running.
The other problem I'm having is, when I do a sample program just running the motors if I hit feed hold, which is the normal way to halt your program, the motors seem to just slow down and squeak to a stop, then I cycle start and they slowly ramp up to speed and carry on, yet If I stop the program, the motors stop instantly, then I cycle start and they start instantly.
All the machines I have worked on don't have a program stop, they just have a feed hold then you would use the reset if you want to terminate the program, am I missing something.
I must admit, I do like the Mach3, I've been around Fanuc for too long….
Regards, Ray.
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Hi Ray
Just wondering what drives you are using and do you have the model numbers and specs for the motors.
Some have 1million pulse per rev encoders and you will need a good set up to run them at normal speeds with such a high encoder count!
John.
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Hi John, The motors are Fanuc AC (red cap) model 0 with 2000 pulse coder.
Ray.
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I forgot, the drive is Fanuc 3 axis in 1 drive.
Ray.
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I see Ray..are you running them straight from the printer port or using a motion card..?
I presume the drive is a A06B-6058-#### Are you routing the encoders to the drive and running open loop step and direction or closed loop with a motion card..?
John
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He is using the DSPMC
Hood
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Ah yes missed that one ;D
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As Hood said, dspmc. It runs OK but the motors are loud.
Ray.
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Still having problems with PID motor tuning. I have tried every combo, known to man, at one time I did get the motor to jump off the bench. I can get them to run, but still loud at rapid 3000mm/min.
Still don't know what's up with the feed hold, short moves in X&Y hit feed hold and the motors just slow down and stop, hit cycle start and they ramp up to speed and carry on.
Hit program stop and the motors stop dead, cycle start and they start instantly and carry on?
Also, how do you turn on the soft limits.
Ray.
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Have you tried using a battery box on the drives without the DSPMC connected to see if the drives themselves are needing tuned?
Hood
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I know I can use a battery box with DC motors, mine are AC.
I do have a friend coming over with a scope to try and tune them.
So what's with the feed hold problem, why not remove the feed hold and use the stop, as I said, any machine I have worked with didn't have a program stop. What is the difference between feed hold and stop on the Mach.
Ray.
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Your drives are analogue input, I presume -10v 0v +10v?
If you put a voltage on command input to the drive surely the motor should turn?
Hood
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Yes, I think you are right, I was thinking of putting the battery box to the motors direct and not through the drive, we did that years ago when we wanted to move large machines but had no power but they were DC motors.
So, about that feed hold, I know why it slows the motors to a stop, that's because you guys use stepper motors and you could loose a step right. I should try to remove the feed hold and rename the stop.
Ray.
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If your acceleration is fast it should stop almost instantly with the feedhold, if it doesn't then it could be an issue with the way the DSPMC handles the feedhold.
Hood
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It says in the Mach manual the the feed hold stops the feed as quickly as possible but in a controlled way, the program stop will stop the feed instantly.
Also I can't find the toggle in the settings screen for turning on the soft limits, Is this because I am only evaluating the software and haven't purchased it yet?
Ray.
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Big button below DROs to the right, says Soft Limits.
Hood
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Hood, you should be tucked up in bed by now...I see the big button but in the manual it shows it in the setting screen by the auto limit on/off. I don't think it's a good idea to put soft limit activation on the operator screen.
Ray.
Canada.
X UK
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It can be placed wherever you want if you use Screen4.
Hood
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What is screen 4 ?
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It is the screen designer utility for Mach, you can make your own screen or just alter standard screens with it, should be on the downloads page. It has a few quirks, main one is to make sure you have your screen resolution set bigger than the screen you are designing or you could end up inadvertently placing buttons off screen. Another is once you have placed a DRO or a Button on the screen you are best to click the None Icon at the bottom so that you don't add any more by mistake. Last thing is if the screenset has a background image you have to disable it before you can place buttons or DROs on screen. To disable you just click on the button at the top that says Img and has a red diagonal line through it.
Hood
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Thanks Hood, I'll try it.