Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: nic6911 on February 26, 2011, 01:35:56 PM
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Hi.
I have tuned my steppers in mach3 and they run smooth at 1000mm/min with acc. set to 200.
Now the speed is to high when cutting in wood, so in my gcode the plunge rate and feedrate are set to 400. But when i do this the steppers doesn't sound right and they loose steps.
I also tried to tune the steppers at 500mm/min, this also causes them to loose steps.
I only thought that i would loose steps when going faster??
But as it is now i can't run my mill slow, so i can't cut in the materials i wan't.
I just can't figure this out, so if you got a clue please feel free to post suggestions! :-)
regards Nic
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have you tried it with the acceleration at a lower setting.
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Yep. My acceleration is set to 200 for now. But i have tried to lower it when i lowered the speed. It's just weired that it looses steps when going slow. It just doesn't seem right. The only speed it runs without loosing steps is around 1000mm/min. Acceleration doesn't affect this.
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Could it be resonance? Maybe your drives have pots for adjusting?
Hood
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I can only adjust decay and current... But yes, it could sound like resonance.. just wondered if any other have had this problem. Still hope its a adjustment problem in the software..
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Just a thought but are you running your steppers 'full step' or are you using microstepping ?
Tweakie.
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1/8 microstep. But the funny thing is that my steppers do 200 steps on a turn which moves 5mm, hut i have to set it to 640 steps/mm when using 1/8 microstepping for it to move 1mm. That does not add up with my calculations...
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Surely that would be 1/16 step then (assuming the screw is directly connected to the stepper without reduction) - very strange. Are they perhaps 400 step per rev steppers ?
Tweakie.
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They should be 200 steps. And the driver is set to 1/8. I bought the steppers in the uk, and the data table says 1.8 degre per step.
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Really, really strange.
There is obviously something wrong with your Mach3 setup or machine somewhere because this just does not make any sense. 200 step at 1/8 with 5mm pitch screws = 320 steps / mm.
Wish I knew the answer.
Tweakie.
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Yep.. that might also cause the problem with the lost steps during slow run? I did the setup as according to the manual...
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If it's resonance, here's an easy way to get rid of it.
http://www.cnczone.com/forums/stepper_motors_drives/32284-my_take_stepper_damper.html#post256639
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Hmm.. I didn't think of that as a problem, but yes, that could be a problem of course... Maybe i will get dampers for the steppers, don't have the the tools for making them myself so will have to buy them.. So I will do a bit of research on google first :)
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I tried too take the stepper on the y-axis of the machine, and then i could feel and hear that the stepper is loosing steps. It didn't matter which speed it was going, it just got woorse when it was running low speeds.
So it is not resonance...
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Tried a wider pulse? (Motor Tuning page)
Hood
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yes, tried with wider pulses, but that doesn't do the trick, also tried sherline mode and changing the frequenzy. The test of the computer says it is perfect for running 35.000hz and also 25.000. But i loose steps no matter what fequenzy i use...
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in config/general config raise the debounce interval to 2000.
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That did not do the trick... isn't debounce for input signals? The computer isn't connected to earth. I might try to do that. It could be noise in from the lpt port I guess?
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The computer isn't connected to earth. I might try to do that. It could be noise in from the lpt port I guess?
Yup - that would do it. ::)
Tweakie.
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Hi again. I have now tried to connect the pc to earth and also the powersupply and -24VDC. That will take all the noise, but still, the steppers are loosing steps, expecially when running slow.
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What make and model driver board are you using for your steppers ?
Tweakie.
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Post info on your driver and motors.
What is the amp and voltage output of your power supply?
RICH
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Hi.
My driver: http://cgi.ebay.com/CNC-3-Axis-Stepper-Motor-Driver-Controller-Board-TB6560-/270705528552?pt=LH_DefaultDomain_0&hash=item3f074e8ee8
the steppers: M57STH76-2808D-1 from: http://www.motioncontrolproducts.co.uk/products/2/5/nema_23_high_torque_stepper_motors/
Power supply is 24vdc 10A.
I know the driver is a bit cheap, but i am low on cash, and i have used a board a bit like this to drive a proxxon MF70 without any problems (using kcam).
I just don't get it.. it drives fine when running 1000 mm/min but runs like ********* when running for example 500mm/min.
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What microstepping do you have set?
Hood
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i have set it to 1/16 right now, but have tried with 1/8 and 1/2...
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Is it all motors that are weird?
Hood
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Yes all of them... they run quite smooth at 1000mm/min. But still looses some steps, but not like when running half the speed. But 1000mm/min is a bit to fast for cutting some materials.
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what if you go half again?
Hood
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i have used a board a bit like this to drive a proxxon MF70 without any problems (using kcam).
Was it the same board and machine along with the same drive settings you are using now and did you try slow speeds at that time when using Kcam via the PP?
Post your xml file.
RICH
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It was not the same board, just a similar one... The settings are different, because it is a different machine. Slow speeds with the other cnc and kcam was possible without any problems.
I just tried to set the microstep back to ½ step. Apparently it works better... not loosing so many steps. But I just tried it quick, i will do an attempt some day next week to see if it really helps.
But is it normal that steppers runs smoother at high speeds?
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I only have experience of Gecko and Leadshine stepper drives and the motors run fine at any speed with them.
Hood
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I use Gecko drives and even the ones a friend made work at any speed and very well. Thus I can't speak for what you purchased, but, believe that's your problem.
RICH