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« on: August 21, 2017, 02:38:35 AM »
Hello Rich.
These are my latest facts.
I tried to find a G code to recreate the problem in a predictable way.
I generated a G code on Cambam for a pocket 12 mm deep in 0.4 mm Z increments and a return to clearance height between each level.
This gave me a beautiful pocket, but found if I machined the same pocket in the same place I had a small Y shift so I generated another G code in Cambam : a series of 10 identical diameter pockets but each one 1 mm shallower all machined in the same place.
This produced a pocket with a series of 1 mm steps in the y+ side of the pocket. Each about 0.01 mm or a total of 0.1 mm increase in the diameter of the pocket from bottom to top in the y plane but not in the x plane.
I swapped my X and Y stepper motors around and the problem occurred on the X axis instead of the Y axis. OK, so it is not the Steppers or Mechanical.
Next I swapped X and Y axis on Ports and Pins. The problem remains on the X axis.
I then corrected the X and Y steppers on their plugs and the problem returned to the Y axis even though the ports and pins were reversed.
I tried the same G code in my old Dads little hobby mill and it worked perfectly.
My conclusion is that there is a problem between the serial port plug and the stepper plug on the driver I am using for thew Y axis.
Now I am using a Geko 540 so I cant change individual drivers but I have a 4th axis spare so I will now run the same test with the ports and pins set to bypass that one axis in the Geko 540.
I will also carefully check all my connections from the Y axis to the Geko 540.
I find it hard to understand why this only occurs on a new pocket, or, when engraving a 3D shape the problem only occurs when a level or section is complete.