[Marankie]

Hi All,

I'm having issues with my axis running properly or smooth. I usually run circles for testing how well it's running. It's a pretty simple setup that I recently upgraded, control box is running a Gecko g540 with 570oz Nema 23s, single motor X axis, using a pulley and belt (XL037) system (which may be the next upgrade on my table to rack & pinion/gear racks).

So I spent a better part of my Sunday tuning and calibrating the axis until I was getting perfect circles. Come in on Monday to cut some production parts and it's way off immediately. Please see attached pics. I realized one pulley was loose on the motor shaft which accounted for one which is really bad, but when I made sure everything was snug and moving smoothly, still getting ovals with really flat tops?

Any suggestions would be appreciated. I'm pretty sure I'm not dealing with any noise issues.

Thank you,

Greg

[tommylight]

As far as i can tell from your pictures, you have the motor pulleys directly driving the belts, so right there you have a "no go" for smal circles. More detailed: you have aprox. 2 cm diameter pulley driving the belt so multyply that with PI 3.14 and you get ove 6 cm of movement with one rotation of the motor. Asuming a standard stepper motor with 200 steps/rev you get 200/60=3.33 steps/mm, so the resolution is bad and due to elasticity of the belts and the force required to actualy start moving the axes, it results in a situation like having backlash although you might not actualy feel it when moving the axis by hand. You have to get some reduction, at least 1:3 ratio for anything usable. Been there done that and it did not work, not much power, to much movement for a single revolution on the motor, low resolution, repeatability goes out the window, etc.
This is also related to software i.e. you need to do a lot of movements of 1.15mm so software must aproximate to 3 OR 4 pulses. Now multyply that and you get huge diferences.
Hope this helps
Tom

[Marankie]

Hi Tom,

I appreciate you taking the time.

Yes, I realized that setup is not going to work for me. I was able to get decent cuts one day by messing with the backlash settings in Mach 3, the next day the same settings would not give me the same results. Way too much slop in belts and setup in general. This has to be fixed mechanically. I ordered all new rack and pinion parts with 3:1 reduction right at the gear rack as well as a 2nd X axis motor for the other side.

This should alleviate my issues. I'll let you know how it works out.

Thank you,

Greg

[tommylight]

I'll check how it goes, of course.
In the mean time check some videos i posted on youtube and on LinuxCNC forums, you might get some ideas there.

LinuxCNC Support Forum :: Topic: THC config that works. (3/3)

Regards,
Tom