Maslow CNC cutting slight curves instead of straight lines

So I have had my Maslow CNC for almost 2 years now. I’ve cut many great projects and with some bugs here and there I have never had any major issues with it. However, after having not used it for a year, I fired it up to cut a sign and the whole sign came out slightly curved. I’ve drawn straight level lines on my spoilboard and run numerous firmware versions and different types of software, Ground Control, Web Control, Universal GCode Sender, Makerverse, etc. but for the life of me, the machine still moves in a gentle curve instead of a true straight line. (For the record, the visualizers in the software all show the machine moving in a straight line according to the coordinates I entered.)

I think it’s a firmware issue, but it is possible one of my chains skipped a link. I’m not really sure how a chain skip could cause curving though.

Please help!

once you are not where you think you are, curves happen.

reset the chain lengths (if you marked the links what were at 12 o’clock when
you finished calibration), or re-do the calibration (and mark the links so you
can do the shorter version next time)

David Lang

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I reset the chains to the mark I made during initial setup, but to no avail. I also tried to move my z-axis, but the values are reversed. Can someone please point me in the direction of a version of the firmware that they know for sure works?

if your Z is moving in the wrong direction, it sounds as if you lost your config
and need to do a full configuration from scratch. If you have one of the
original type of machines, webcontrol with holey calibration is the recommended

David Lang

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Webcontrol .94 and firmware 51.27 works well for me.

Your z axis depending on how it is mounted requires a negative or positive pitch setting.

I agree with dlang that you will need to recalibrate, sounds like you lost all your calibration settings.

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Ok, so I’ve made some updates to my frame before resetting and recalibrating by replacing the top bar (which was horrendously warped) with an aluminum square tube that is much more rigid. I reset the chains from scratch and recalibrated which has fixed the x and y-axis movement issues. The remaining problem is my z-axis is still running in reverse. And in much largest increments than the 1 mm it is supposed to be moving. I know I corrected this once, but I don’t remember how.

I made a video on how to calibrate with makerverse a couple years ago and in there at about 10:30 it shows the z axis setup and how to reverse the z axis that was moving backwards.

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If using webcontrol under z pitch settings change -/+ if going in the wrong direction.

Baseline settings for gear setup:
3:1 = -24 (ex: 30T and 10T, 60T and 20T)

2:1 = -16 (ex: 20T and 10T, 40T and 20T)

1:1 = -8 (ex: 10T and 10T, 20T and 20T)

Default for direct coupler

To fine tune the depth:

To calculate the movement error:
E = D2 / D1
E = Error
D2 = Distance the carriage actually moved
D1 = Distance the carriage was requested to move

To calculate the corrected setting:
C = Z * E
C = Corrected Z-Axis mm/rev
Z = Z-Axis mm/rev from the test
E = Error

(Taken from the Meticulous Z instructions)

There are two parameters, one is the thread pitch (number of turns per inch) and
this can be negative to reverse the direction you move.

David Lang

in makerverse, it is $3=0 or $3=4 or use the dialog shown in the video and press the button to reverse it.