I think the problem is in the Harley Davidson-7.ai file that you imported. If you change NOTHING in the file and preview the toolpaths, that comes out looking pretty crappy.
Start over and use the text tool with an appropriate font and continue from there. Also know that, unless you're cranking it down with the dial on the HUST controller, you've set the spindle speed to 18,000 rpm. That's a 2 flute bit and you would need to drop your spindle speed to 12,000* and up your feed rate to 100 ipm to come up with a chip load within the optimal randge (for MDF) of .004" to .007"
This file also shows that your are using a 1/8" end mill with one single pass of 1/8" for a cut depth of 1/8". You may be getting bit flex as well. It takes longer to make 2 passes (but remember, you're upping your feed rate), but try going 1/2 that depth and making 2 passes.
* Note that...on this machine, the spindle speed is NOT set by the software, it's only set on the controller. The maximum feed rate can be set in the software, and decreased at the controller (but cannot be increased beyond the feed rate that comes over from the software).
Last Edit: Sept 17, 2019 18:20:24 GMT -5 by johnb: clarification by *note