Ok well Agree most of this is motor tuning and like Jonathan suggest you balance the tuning up.!! . . . But looking at the frame it has some serious issues.?

Quote Originally Posted by cncJim View Post
Love the idea to diy support my existing rails! Not sure I have the tools or skills to pull it off though
Following on from above statement regards serious issues then I wouldn't suggest you do because there are other problems that will make any attempt pointless without addressing these problems also has they are quite big ones.

The Gantry and the way it fastens to the bearings is a major weakness. It's only mounted to the X axis bearings with 2 bolts per bearings plus the mounting plate area is woe fully inadequate. Also the fastening of the Y axis rails into the puny narrow gantry ends is very weak and the whole thing must flex quite badly and could be some of the problem on direction changes with deep Cuts.

Like said before given the parts you have already and spending a few hundred quid building a new frame will be far far better solution that will give a very good machine that will do every thing you want and to good standard for years, and still be worth more money than you invested when time to sell.!!