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Author Topic: Very green newb, Is this possible?  (Read 7339 times)

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Very green newb, Is this possible?
« on: August 31, 2009, 09:56:14 AM »
I am very new to cnc, and have recently built a Phlatprinter MKII from phlatboyz.com  I am using a Mechatronics bi polar 3 axis micro step motor driver, with 3 nema-23 stepper motors.  The machine is all belt driven.  The x axis is a large belt driven roller similar to that of a large format printer.  Y and Z are on a gantry below the cutting surface, and the cutting bit protrudes from below.  When I run a cut file X and Y do not finish where they start.  Y drifts progressively farther and farther in the + direction, and Z does so as well.  To help diagnose the problem I rewired coil 1 to coil 2, and coil 2 to coil 1 reversing the steppers, then in mach I reversed settings so everything ran in the right directions again.  After reversing the steppers I still have the drift but in the opposite directions.  The drift is very consistant.  The same cut file ran over and over leaves the cutter the same distance off.  I have tried lowering the feed rates and acceleration, with no changes in the drift.

Is it possible that one coil is working better than the other in the steppers?  If I could set steps per unit in the + direction, and then in the - direction independantly couldn't I compensate for this drift?

Jeff
Re: Very green newb, Is this possible?
« Reply #1 on: August 31, 2009, 11:43:54 AM »
Sometime, board can miss step because of the optocoupler that are not fast enough. In motor tuning, try to increase the step and direction duration, if you have one in both , try with 5.
Re: Very green newb, Is this possible?
« Reply #2 on: August 31, 2009, 12:09:35 PM »
What breakout board are you using?

Regards,
Ray L.
Regards,
Ray L.
Re: Very green newb, Is this possible?
« Reply #3 on: August 31, 2009, 09:03:41 PM »
Ray L.       I am using a mechatronics bi polar 3 axis micro step motor driver, from www.easy-cnc.com  , 

ostie01    I have already tried increasing the step and direction pulse
Re: Very green newb, Is this possible?
« Reply #4 on: September 01, 2009, 12:19:22 AM »
It could be mechanical?  Have a VERY close look at your belts/pulleys when you are running your program.  Are you slipping a tooth on your pulleys?  Sometimes this will happen if your belts are not tight.

Offline RICH

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Re: Very green newb, Is this possible?
« Reply #5 on: September 01, 2009, 07:11:03 AM »
FAOMLVR,
Are you steps per units correct?
RICH
Re: Very green newb, Is this possible?
« Reply #6 on: September 01, 2009, 08:47:59 AM »
sshneider     belts and pulleys are tight, been through this thing with a fine tooth comb,  also checked set screws, all stepper shafts have flats ground for the set screws.

RICH    Steps per unit are as close as I can get them, with a 6" digital vernier calipers.  Regardless of whether they are right or not shouldn't zero be zero?

Offline Hood

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Re: Very green newb, Is this possible?
« Reply #7 on: September 01, 2009, 09:12:33 AM »
Have you tried changing the Active state of the Dir signal?

Hood
Re: Very green newb, Is this possible?
« Reply #8 on: September 01, 2009, 03:54:54 PM »
Hood    If you mean "dir lowActive"  Ports & Pins,  Motor Outputs,   then yes I have tried it.

I may have found something,  I don't know what video card I have.  The system is fast enough, and has enough memory, but I don't know what video card I have, or how to find out.

Another thing I found,  today I was listening to the radio,  when I powered up my machine I got a lot of static on my radio.

Jeff

Offline Hood

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Re: Very green newb, Is this possible?
« Reply #9 on: September 01, 2009, 05:42:31 PM »
Is it an onboard card or is it an AGP?
Right click on desktop, choose properties then settings tab then advanced tab then finally adapter and it will tell you the card make/model etc you have.
Hood