Okay, I tried the suggestion of flipping the bottom mount for the Dewalt over and I still cannot get both bolts on the upper mount secured. I made sure both halves of each were flipped in the same direction, and still nothing. Best I managed to do is twist the Dewalt a little but it still isn’t 100% secure. For now, it will have to do. From what I can tell it seems to be secure so as long as there are no issues with it as I start cutting more and more I should be fine. I do plan on upgrading the spindle at some point anyways.
I also swapped out the top Z motor mount for one with a Vac holder attachment. I plan on adding a Vac plate to the bottom so as to help keep the dust to a minimum.
And lastly, I managed to figure out what I was doing wrong in EstlCam and why the cuts I programmed in didn’t come out. The DWG file I downloaded was WAY too small, so the tool was performing the cuts, just on a microscopic level. I had to scale the image up 200%.