Hi, I am using Mach3 to run a specialised 3D printer. I'm trying to print a simple structure, a grid with diamonds inside (see attached Mach3 print path) but when changing direction one of the values halves depending on the new direction (see attached printed product). As the path is diagonal I can't tell if it is the left to right change or upward to downward causing the problem. Does anyone know what setting might be causing this?

As a test, try running Mach3 in Exact Stop mode (Config. : General Config. : Motion Mode : Exact Stop)

Does it now follow the correct toolpath ?

Tweakie.

Thanks for the suggestion but it didn't fix it. I have a diagram of the tool path here split into two parts and one of them overlapping so you can see exactly what it does (top pics are what it should be, bottom pics is what is happening on my machine). It seems that when it changes from diagonal movement to straight movement at the sides and corners it either halves or doubles the straight distance (alternating between half and double depending if changing from left to right, right to left or up to down, down to up. My overall shape (outer dimensions) is maintained but the internal path is changed (see attached - the blue line is the final movement before it does the next half). If I run a similar path without diagonals the issue doesn't occur (ie a cube with little cubes inside it instead of a cube with diamond shapes inside).

Can you please attach one of your problem Gcode files then I can run it here and try to find the problem.

Tweakie.

Also under general config, might wanna try:
remove tool offset
distance mode and IJ mode, swap what they are and try again

Okay, I'll try checking the Remove Tool offset and swap the IJ and get back to you. Here is the code (it's running a specialised 3D printer so is just a 2D path). It looks correct on the toolpath screen.