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Author Topic: Circles aint Round  (Read 2627 times)

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Circles aint Round
« on: February 19, 2008, 11:58:15 PM »
Hello Guys,

I'm not sure whether it's the right place to post this, but i am facing this problem..
 
I have 2 units of 1800 oz/in KelingInc 8.8Amp stepper motor configuration, with the combination of G203V.

This is hooked and together controlled with Mach3.

I am getting a very weird response from the g-codes being run.

I used SheetCAM and generated a g-code of a circle in a diameter of 500mm. I send it over to Mach3, fitted a pen (as a CNC plotter) and start plotting in the paper. The result was unexpected. The circle seemed to be flat when reaching the edge of the circles, as it there was a shaft with 4 keyways milled on it. A picture is posted to reflect the explanation.

When I program Mach3 to plot is slowly, the CNC seems to be ignoring slower pulses. If fast, the circle will look better. If too slow, the motors doesnt move at all. minimum speed that can be run is 700mm/min or higher. At 700mm/min, the circles are just like rectangles O.O

In conclusion, I feel that the steps are rough. Can anyone help me out? Thanks in advance.

Charles

Offline Chaoticone

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Re: Circles aint Round
« Reply #1 on: February 20, 2008, 12:23:11 AM »
Sounds like backlash to me. Can you post the code and pictures of the circles?

Brett
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Online Tweakie.CNC

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Re: Circles aint Round
« Reply #2 on: February 20, 2008, 12:09:19 PM »
Hi Charles,

I take it that you have run the Mach drivers test program and all is OK ?.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Circles aint Round
« Reply #3 on: February 20, 2008, 08:57:06 PM »
Yep, i have done all the Mach3 drivertest and other things that I could think of. I have already assembled 4 CNCs during the past, but it's that motor that makes me feel so inconfident.

Charles
Re: Circles aint Round
« Reply #4 on: February 21, 2008, 10:44:29 AM »
Just a thought but,
What is your step-resolution? If the step resolution is wrong the motor wouldn't move untill the move command is great enough for the drive to move the motor a"step"
Also circles would look rough.

Cutmore