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Author Topic: Roatary/stepper stalling  (Read 6027 times)

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Roatary/stepper stalling
« on: April 08, 2007, 11:47:52 AM »
OK I am just getting around to using this cnc rotary table I built. it uses a stepper motor currently set up for half stepping. the rest of my mill is outfitted with servo drives. my problem is. for one my stepper motor sounds like it could run smoother but all my attempts to tune it have yeilded little results. anyhow. when Im running a program say doing some rotary slotting, when ever the stepper is running and another axis on the table starts to move I get a jerk out of the stepper. or if the feed rate is set pretty fast The motor will stall all together. If I over ride the feed rate and slow it down it improves someone and I can keep it from stalling. but I would like to fix it all together if I could. Is it just that steppers arnt ment to run very fast or what. what kind of max rpm should I expect out of a stepper motor. anyone else have this problem

Hood

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Re: Roatary/stepper stalling
« Reply #1 on: April 08, 2007, 12:02:01 PM »
What drive are you using? what size stepper? ratio? Steps?
Can you run the stepper at full rapids on its own?
Never had a fourth axis so might not be much help but do use steppers on my mill.
Hood
Re: Roatary/stepper stalling
« Reply #2 on: April 08, 2007, 12:29:51 PM »
its a gecko 210 stepper drive

the motor is a nema 34  762 0z 3amp wired in parrallel
step angle 1.8

Ive tried to reproduce the problem while jogging but it runs smooth as can be. only when running an actual program do I get a problem.
kinda strange. but Ive had a problem like this before until I finally got a faster processor computor and have had no trouble. but that had to do with my servo's. steppers, well Im lost with them.


Re: Roatary/stepper stalling
« Reply #3 on: April 08, 2007, 12:33:29 PM »
also how smooth should my stepper run. If I just run it at a rapid I can here it kinda skipping every few rotations. its kinda hard to check if Im losing steps on a rotary table though since I have no way to home it and no encoder.

Offline Chaoticone

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Re: Roatary/stepper stalling
« Reply #4 on: April 08, 2007, 02:25:08 PM »
Hey GNB,
    Your stepper should run very smooth. Try turning down your accel and vel. in motor tuning and see if it sounds smoother. Sounds kinda like a noise issue to me. Also, post your code for us to see and notice if when it messes up while running code is it trying to move two axis at once at the same feed rate? One way to check and see if it is skipping steps would be to put a mark on the table and command a move equal to one rev. and see if the marks line back up.


Brett
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Re: Roatary/stepper stalling
« Reply #5 on: April 08, 2007, 06:46:47 PM »
yeah Iv played with the velocity alot and no matter what I do I get a skipping noise (is all I can describe it as) itl be a nice humm with small breaks in it. Ive tride setting a block up on the rotary table to indicate off of and i dont seem to be losing steps. as for when it stalls you got it right basicaly when I have the mill feeding into the work as it is spinning when the mill reaches depth the table keeps spinning while the Xaxis moves left than right to clean out the slot. its when the x axis tries to move when the motor stalls. If its a noise problem it doesnt seem to affect the rest of my set up. but again Im not sure how easily steppers are affected by noise. my servos run great.
will post the code.
Re: Roatary/stepper stalling
« Reply #6 on: April 08, 2007, 06:53:17 PM »
here is the basic program. I havent really cleaned it up yet so bare with the lack of line numbers. was just trying to test it first.
G90 G94 G64 (SETUP PARAMETERS)
M6 T4 (TOOL4)
M08 (COOLANT)
M03 (SPINDLE ON)
G00 X0 Y0 Z.2
G00 X-.625
G00 Z0
G91 G01(INCRIMENTAL)
G01 Z-.05 A360 F20 (SLOT RUN)
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.0125 A360 F20
G01 A360 F20 (BOTTOM OF SLOT)
G01 X.01 A90 (WIDEN SLOT)
G01 A360
G01 X-.02 A180
G01 A360
G01 X.01 A90
G00 Z.3125 (RETURN TO 0)
G90 (ABSOLUTE)
Z.2 (SAFEZ)
G00 X-1.125
G00 Z0
G91 G01(INCRIMENTAL)
G01 Z-.05 A360 F20 (SLOT RUN)
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.0125 A360 F20
G01 A360 F20 (BOTTOM OF SLOT)
G01 X.01 A90 (WIDEN SLOT)
G01 A360
G01 X-.02 A180
G01 A360
G01 X.01 A90
G00 Z.3125 (RETURN TO 0)
G90 (ABSOLUTE)
Z.2 (SAFEZ)
G00 X-1.625
G00 Z0
G91 G01(INCRIMENTAL)
G01 Z-.05 A360 F20 (SLOT RUN)
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.0125 A360 F20
G01 A360 F20 (BOTTOM OF SLOT)
G01 X.01 A90 (WIDEN SLOT)
G01 A360
G01 X-.02 A180
G01 A360
G01 X.01 A90
G00 Z.3125 (RETURN TO 0)
G90 (ABSOLUTE)
Z.2 (SAFEZ)
G00 X-2.125
G00 Z0
G91 G01(INCRIMENTAL)
G01 Z-.05 A360 F20 (SLOT RUN)
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.0125 A360 F20
G01 A360 F20 (BOTTOM OF SLOT)
G01 X.01 A90 (WIDEN SLOT)
G01 A360
G01 X-.02 A180
G01 A360
G01 X.01 A90
G00 Z.3125 (RETURN TO 0)
G90 (ABSOLUTE)
G00Z.2 (SAFEZ)
G00 X-2.625
G00 Z0
G91 G01(INCRIMENTAL)
G01 Z-.05 A360 F20 (SLOT RUN)
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.05 A360 F20
G01 Z-.0125 A360 F20
G01 A360 F20 (BOTTOM OF SLOT)
G01 X.01 A90 (WIDEN SLOT)
G01 A360
G01 X-1 A7200 F20
G01 A360
G01 X.01 A90
G00 Z.3125
G90 (ABSOLUTE)
M9 M5 (COOLANT AND SPINDLE OFRF)
G00 Z.2
X0 Y0 Z.2
M30


woo a bit long for a post . but heh
chris
Re: Roatary/stepper stalling
« Reply #7 on: April 09, 2007, 03:30:12 PM »
here is an update on what I found.
Im begining to think that there may be a problem with the motor itself. Its just making this funny ticking noise while it runs and nothing I have tried really changes it much. except I tried changing the kernel speed of the computor down to 25000 hz and it seems to be a less frequent tick. but it still ticks non the less. Ive tried running in Full, Half ,5 , and 10 microsteps and none of that affects the noise coming from the motor. also I found that when Im running the below program the motor will hesitate just slightly between lines of code. even though its in CV mode it slows slightly like its going to change directions. If I slow the feedrate down to say 10 it will not stall. and by 10 I mean Inches per minute not degrees per minute. I am using the "use diameter for feedrate setting" from the toolpath screen. was also curiouse what the "A rotations enabled" check box does?
Re: Roatary/stepper stalling
« Reply #8 on: April 10, 2007, 09:14:35 AM »
Please post you XML and i will check to see if there is a problem

Thanks
Brian
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Re: Roatary/stepper stalling
« Reply #9 on: April 10, 2007, 11:09:42 AM »
sure