Losing My Way
28 Jan 2015 08:39 - 28 Jan 2015 08:54 #55403
by jorsborn
Losing My Way was created by jorsborn
I am looking for suggestions on a problem I am having. I have a large 4'x8' gantry with two motors on the Y axis. All motors are stepper driven using G540 connected to the parallel port. I was having significant issues with the gantry racking so I've tried a bunch of things to try and nail down the source of the problem.
- I've examined the linkages on the two motors. Set screws are tight and there is no play in either.
- I've swapped drivers. What I mean by this is I have taken two other drivers (of the 4 in the G540) and substituted them in to see if it was a driver issue.
- I've changed out the external LPT card for an onboard card.
- I've changed the motherboard.
- I've changed the LPT cable so that one set of step/direction pins are now the input to both drivers. I also had to swap a phase on one of the motors to make this work.
- I've tried running at very low speeds.
- I've tried cutting air alone.
The only things I have not tried at the moment are subbing in a new power supply (48VDC 1000W), changing out the G540 and making use of some sort of breakout board which will accept the 3.3V signals from the LPT card and output at 5V so that I am not operating near the low end of the G540 input specs.
I am attaching a picture of a part which illustrates the problem.
- I've examined the linkages on the two motors. Set screws are tight and there is no play in either.
- I've swapped drivers. What I mean by this is I have taken two other drivers (of the 4 in the G540) and substituted them in to see if it was a driver issue.
- I've changed out the external LPT card for an onboard card.
- I've changed the motherboard.
- I've changed the LPT cable so that one set of step/direction pins are now the input to both drivers. I also had to swap a phase on one of the motors to make this work.
- I've tried running at very low speeds.
- I've tried cutting air alone.
The only things I have not tried at the moment are subbing in a new power supply (48VDC 1000W), changing out the G540 and making use of some sort of breakout board which will accept the 3.3V signals from the LPT card and output at 5V so that I am not operating near the low end of the G540 input specs.
I am attaching a picture of a part which illustrates the problem.
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28 Jan 2015 23:13 #55422
by alan_3301
Replied by alan_3301 on topic Losing My Way
I cut aluminum on my diy machine with nema 34 steppers w/ g201x's @ 48v with a 1/4" 2 flute carbide @ 0.080" DOC and 50ipm
I have done the same with a nema 23 g540 driven machine, but with a smaller DOC.
I have cut as deep as 1.125"
In both cases, the finish isn't great, you can see some ripples and variations, but nothing like in the pictures posted.
I didn't realize the g201's were good for 80v, Now you have me thinking about upgrading my power supply!
Thanks alot BigJohnT
I have done the same with a nema 23 g540 driven machine, but with a smaller DOC.
I have cut as deep as 1.125"
In both cases, the finish isn't great, you can see some ripples and variations, but nothing like in the pictures posted.
I didn't realize the g201's were good for 80v, Now you have me thinking about upgrading my power supply!
Thanks alot BigJohnT
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29 Jan 2015 01:05 - 29 Jan 2015 01:13 #55425
by jorsborn
Replied by jorsborn on topic Losing My Way
Thanks all for the responses. I am attaching a picture of the gantry as well as the linkage. The build is mostly based on the structure developed by CNC router parts.
Alan, in this particular instance I am not good about clearing the chips as it gets deep into that slot. I can't say for sure that this is not a contributing factor but I do know that the gantry racks when simply cutting air on some files. There must be particular moves which exacerbates the problem because some files are really problematic. The pen idea is a smart one and I think I'll have a go with that. I'll report back.
The material being cut here is delrin. I am running at approximately 800 SFM (0.25" diameter carbide cutter, 12,000 RPM). My feed rate is set to 30 ipm.
My ini configuration file is below:
Alan, in this particular instance I am not good about clearing the chips as it gets deep into that slot. I can't say for sure that this is not a contributing factor but I do know that the gantry racks when simply cutting air on some files. There must be particular moves which exacerbates the problem because some files are really problematic. The pen idea is a smart one and I think I'll have a go with that. I'll report back.
The material being cut here is delrin. I am running at approximately 800 SFM (0.25" diameter carbide cutter, 12,000 RPM). My feed rate is set to 30 ipm.
My ini configuration file is below:
# Generated by stepconf at Sun Jul 28 22:35:21 2013
# If you make changes to this file, they will be
# overwritten when you run stepconf again
[EMC]
MACHINE = router
DEBUG = 0
[DISPLAY]
DISPLAY = axis
#PREFERENCE_FILE_PATH = gmoccapy_preferences
EDITOR = mousepad
POSITION_OFFSET = RELATIVE
POSITION_FEEDBACK = ACTUAL
MAX_FEED_OVERRIDE = 10.0
INTRO_GRAPHIC = linuxcnc.gif
INTRO_TIME = 5
PROGRAM_PREFIX = /home/jorsborn/linuxcnc/nc_files
INCREMENTS = .1in .05in .01in .005in .001in .0005in .0001in
EMBED_TAB_NAME = Camera
EMBED_TAB_LOCATION = ntb_user_tabs
#EMBED_TAB_COMMAND = ./camview-emc-f1oat.py -v 1280x720 -C camview.cfg -g cam.ui -H campins.hal -w {XID}
#PYVCP = custompanel.xml
[FILTER]
PROGRAM_EXTENSION = .png,.gif,.jpg Greyscale Depth Image
PROGRAM_EXTENSION = .py Python Script
png = image-to-gcode
gif = image-to-gcode
jpg = image-to-gcode
py = python
[TASK]
TASK = milltask
CYCLE_TIME = 0.010
[RS274NGC]
PARAMETER_FILE = linuxcnc.var
[EMCMOT]
EMCMOT = motmod
COMM_TIMEOUT = 1.0
COMM_WAIT = 0.010
BASE_PERIOD = 30000
SERVO_PERIOD = 1000000
[HAL]
HALUI = halui
HALFILE = router.hal
HALFILE = xhc-hb04.hal
#HALFILE = joypad.hal
HALFILE = custom.hal
POSTGUI_HALFILE = custom_postgui.hal
[HALUI]
# add halui MDI commands here (max 64)
MDI_COMMAND = G38.2 Z-2 f16
MDI_COMMAND = G10 L20 P0 Z.062
MDI_COMMAND = G0 Z2
MDI_COMMAND = G0 X0 Y0 Z0
MDI_COMMAND = G0
MDI_COMMAND = G0
MDI_COMMAND=G10 L20 P1 X0
MDI_COMMAND=G10 L20 P1 Y0
MDI_COMMAND=G10 L20 P1 Z0
MDI_COMMAND=G0 X0 Y0 Z0
[TRAJ]
AXES = 4
COORDINATES = X Y Z Y
MAX_ANGULAR_VELOCITY = 360.00
DEFAULT_ANGULAR_VELOCITY = 36.00
LINEAR_UNITS = inch
ANGULAR_UNITS = degree
CYCLE_TIME = 0.010
DEFAULT_VELOCITY = 100.00
MAX_LINEAR_VELOCITY = 300.00
[EMCIO]
EMCIO = io
CYCLE_TIME = 0.100
TOOL_TABLE = tool.tbl
[AXIS_0]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 120
MAX_ACCELERATION = 40
STEPGEN_MAXACCEL = 80
SCALE = 1736.237
FERROR = 1
MIN_FERROR = 0.01
MIN_LIMIT = -.5
MAX_LIMIT = 49.5
BACKLASH = 0.005
HOME_OFFSET = 0.0
[AXIS_1]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 120
MAX_ACCELERATION = 40
STEPGEN_MAXACCEL = 80
SCALE = 1736.237
FERROR = 1
MIN_FERROR = 0.01
MIN_LIMIT = -.5
MAX_LIMIT = 99.0
BACKLASH = 0.005
HOME_OFFSET = 0.0
[AXIS_2]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 3
MAX_ACCELERATION = 10
STEPGEN_MAXACCEL = 25
SCALE = 4000
FERROR = 1
MIN_FERROR = 0.01
MIN_LIMIT = -6.0
MAX_LIMIT = 6.0
HOME_OFFSET = 0.0
[AXIS_3]
TYPE = LINEAR
HOME = 0.0
MAX_VELOCITY = 120
MAX_ACCELERATION = 40
STEPGEN_MAXACCEL = 80
SCALE = 1736.237
FERROR = 1
MIN_FERROR = 0.01
MIN_LIMIT = -.5
MAX_LIMIT = 99.0
BACKLASH = 0.005
HOME_OFFSET = 0.0
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