Y axis moves instead of X axis

[aguskov]

Dear Fellow,

I am very new to CNC. I have just started to use a simple 3 axial router and run into a problem when trying to profile a simple circumference

I generate my code using RhinoCAM with Mach3 post since my machine is controlled by Mach3. Here is the problematic part of the code:

Beginning
G00 G49 G40.1 G17 G80 G50 G90
G21
(2 1/2 Axis Profiling)
M6 T1
M03 S15000
G01 X51.4000 Y40.0000 Z1.6000 F130.0
Z-2.0000 F30.0
X51.2752 Y41.8246 F60.0
X50.9031 Y43.6153
X50.2906 Y45.3386
X49.4492 Y46.9624
X48.3945 Y48.4566
X47.1462 Y49.7932
X45.7275 Y50.9474
X44.1649 Y51.8977
X42.4874 Y52.6263
X40.7263 Y53.1197
X38.9144 Y53.3688
X37.0856
X35.2737 Y53.1197
X33.5126 Y52.6263
X31.8351 Y51.8977
X30.2725 Y50.9474
X28.8538 Y49.7932
X27.6055 Y48.4566
X26.5508 Y46.9624
Continuing

The step marked in bold is where I get the troubles. Technically, the X axis is supposed to move from 38. 9144 to 37.0856 and the Y axis should not move at all (as far as I understand). What I am getting is the exact opposite - the Y axis moves and the X axis remains still.

I have tried changing the code:

G00 G49 G40.1 G17 G80 G50 G90
G21
(2 1/2 Axis Profiling)
M6 T1
M03 S15000
G01 X51.4000 Y40.0000 Z1.6000 F130.0
Z-2.0000 F30.0
X51.2752 Y41.8246 F60.0
X50.9031 Y43.6153
X50.2906 Y45.3386
X49.4492 Y46.9624
X48.3945 Y48.4566
X47.1462 Y49.7932
X45.7275 Y50.9474
X44.1649 Y51.8977
X42.4874 Y52.6263
X40.7263 Y53.1197
X38.9144 Y53.3688
X37.0856 Y53.3688
X35.2737 Y53.1197
X33.5126 Y52.6263
X31.8351 Y51.8977
X30.2725 Y50.9474
X28.8538 Y49.7932
X27.6055 Y48.4566
X26.5508 Y46.9624

but is still moving the Y axis instead of the X

If anyone knows what is going on, please help me out because I am just lost.

Thank you very much
Andrey

[awerby]

At first it sounded like you had your X and Y axes swapped, which is easy to fix (in Ports and Pins/Motor outputs). But if you're talking about one single command in a whole string of them, then you might just be looking in the wrong place. Mach doesn't necessarily show you exactly the move that's happening right when it's executed - usually the numbers in the box are off by three or four commands. Does it seem to basically move in a circle, or is it doing something else? When you jog the X axis, does X move, or Y? If you zero the X axis and give it a MDI command like G0X20.0, does the X axis move 20 mm to the right, or does Y move?

Andrew Werby
ComputerSculpture.com — Home Page for Discount Hardware & Software

[ger21]

Run it in Single Step mode, and see if it does it on that exact line.

[aguskov]

Thank you for you replies. I found out what the problem was. Funny thing, actually...

It turns out I had the backlash movement enabled in the program and it was way greater than the backlash of the machine. So it was adjusting the Y axis right at the point where it was changing the direction (and where the X movement was executed). Lowering the programmed backlash worked like a charm.

Thanks for the input.

Andrey