Inconsistency in hole depths

I’m facing an issue while trying to mill out some holes in some 6061 aluminum tubing. Currently, I’m using Solidworks and HSMXpress to create my parts and G-Code, and then importing them into Easel.
The machine will move and create the first hole, and even though I set just on top of the material, it will take a few air passes before finally entering the material. In addition, the left side of the hole will start to mill before the right side. I ordered the large bit for planing the wasteboard and still face this issue. The main matter is that while the material is 0.125" thick, the machine won’t even reach the bottom of the contour before moving on, starting slightly above the location of the next hole and taking even more air passes.
The only way I’ve been able to fully punch through is by setting my material as .165" and even then, the same issues occur. Either this is me being very dumb with the settings in HSM. For reference, I’m trying to use 2D contour to cut out 1.125" circles to fit bearings into.

Some basic specs:

  • 1000mm
  • Dewalt 611
  • Machine bolts for stiffening mod
  • x and y axis calibrated
  • z calibrated to the best of my ability
  • Solidworks and HSMXpress
  • Potentiometers tuned to the best of my ability
  • Flat work surface with the planing bit

Thanks in advance


Can you post a picture of what yoyr trying to cut so I can get a better idea?

Hopefully this helps!

Slipping on your z axis. Your pulley is probably slipping or you are losing steps because it is difficult to plunge into aluminum. Do you have a flat on your z-axis stepper motor to engage the grub screw?