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Messages - doughboy

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General Mach Discussion / Re: Z Axis Stops Working / Fails To Move
« on: August 24, 2012, 05:13:15 PM »
Yep, I've experienced this problem myself.  I ran onto this one trying to fix my own random motor stall problem.  I figure an overload condition induced a motor stall in the 'x' axis while all 3 axes were 'going-at-it' so to speak.  I think Russ could be right... 'the power supply could be stalling during a combined axis G0 move due to excessive heat.


General Mach Discussion / Which step setting to use...
« on: August 20, 2012, 01:39:14 PM »
Hello again everyone,

Well, I have my cnc router working pretty good except for a few minor issues..

I have a ‘homebuilt’ 3 axis flatbed CNC router.  The stepper motor chopper boards can be set for 1 step, ½ step, ¼ step, 1/8 step and 1/16 step.  What are the differences between these setting and which one should I use??  Right now, I have all three motor choppers set for 1/8 step ( ...just picked it out-of-the-blue).  The ‘X’ axis motor is on a 2:1 ratio, the ‘Y’ axis is on a 1:1 ratio and the ‘Z’ axis is on a ½” per turn lead screw.  Should I change the step setting on any one or all of the motors?

Also, occasionally I have experienced a few motor stalls both during operation and during jogging and the ‘Y’ axis has a ‘jerky’ ramping motion.  Could this caused by a motor tuning issue?

Thanks a lot for your help,


G-Code, CAD, and CAM discussions / Re: Large circles in g-code...
« on: August 04, 2012, 11:40:43 PM »

Thanks Gerry..!!  This fixed it..!!


G-Code, CAD, and CAM discussions / Large circles in g-code...
« on: August 04, 2012, 08:04:14 PM »
hello everyone,

Well I'm back with another problem...

I posted g-code using a trial version of Vectric Cut3D using a sample file supplied with the software that was supposed to allow you to save the tool path to g-code.  When I load the g-code file using Mach3 several large (magenta) circles appeared in the g-code preview window.   looked like these large circle were actually short circular segments between points A and B that went around in the opposite direction from point B to point A.

What do you think?  Does anyone know what caused them?


General Mach Discussion / Re: Egg shaped circles
« on: August 04, 2012, 06:57:29 PM »
Hello again everyone,
Yeah, Rich was right, the problem was mechanical.  it was a coupling.  I have a fix for it.

Thanks everyone..!!


General Mach Discussion / Re: Egg shaped circles
« on: June 12, 2012, 09:46:51 PM »

I'm going to talk to tech support tomorrow on the phone.  I'll let you know...


General Mach Discussion / Re: Egg shaped circles
« on: June 12, 2012, 04:22:43 PM »
Hello everyone,

The tech support guy for Probotix says it could be caused by 'missing steps' in the motor, which is a motor tuning issue.  Anyone have any advice??


General Mach Discussion / Re: Egg shaped circles
« on: June 12, 2012, 02:08:04 PM »
Rich and Graham,

I think I already determined that the problem wasn't mechanical...  I attached a small piece of tape on the shaft on the back of the motor and you can see the tape move with the translation.  I'll send pictures later...
The 'Y' axis is driven by a timing belt system coupled to the motor using a clamp type spiral cut anti-backlash coupling.

General Mach Discussion / Re: Egg shaped circles
« on: June 11, 2012, 10:09:44 PM »
Thanks Dave.  I'll try it.  Hum... I wonder if I could swap the wires at the chopper board?


General Mach Discussion / Egg shaped circles
« on: June 11, 2012, 03:54:48 PM »
Hello everyone,

Well, I’ve got my NC router back up and running again.  It was down for a short period after Initial testing to work out a few issues, to finish construction and for painting.

Everything works good except for one small problem… I have a small amount of backlash in the ‘Y’ axis that I can’t seem to get rid of.  With the machine ‘powered up’ there’s about a ¼ inch free travel in the ‘Y’ axis.  The ‘X’ and the ‘Z’ axes are working fine.  If you cut a circle this backlash causes a small flat spot in the ‘X’ at the top and bottom of the circle (See attached pdf).

It looks like to me that the problem might be in the motor.  I thought, at first that the backlash was caused by a Lovejoy spider coupling between the motor and the ‘Y’ axis shaft.  I have since changed out the spider coupling with a spiral cut anti-backlash coupling and the problem still exists.  If you watch the mechanism while moving the carriage by hand with the machine ‘powered up’ you can trace the movement all the way back to the motor shaft.  I have a 400 oz in stepper motor operating the ‘Y’ axis.  From what I understand that motor is supposed to hold tight 400 oz in of force… I’m I right??  While moving the carriage by hand, you can feel a definite hard stop on either side of the free travel.  If you keep applying more force, you can feel it jump over the hard stop to the next one.  Also, while the motor is ramping up during jogging, you can detect a slight ‘jerking’ in the ‘Y’ direction.

I think that the problem could be caused by one of several things.  One is, the chopper board for this motor set for 1/8 step.  Should I try changing it to ¼ step or 1/16 step?  Could it be a bad motor or a problem with the motor wiring?  Could it be a motor tuning problem?

What do you think?  Does anyone have any ideas how to solve this problem that I could try?  Please help!!


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