New member from Farnborough

[m_c]

I wouldn't even consider trying aluminium with a standard 3020.
BTW, you've got a 3020T, the T being for Trapezoidal leadscrews. These are less efficient than a ballscrew (a Z instead of a T on these denotes ballscrews), and will usually have more backlash (free play).

Spending some time on the 3020 would improve it, but you'd need access to some measurement tools, mostly a DTI (Dial Test Indicator) so you can measure and locate backlash.
If the T version is anything like the Z version, a basic improvement is replacing the bearings used to control the leadscrew end float, as on the 3040Z I bought, these were complete rubbish. Tightening to remove play resulted in very notchy movement, and loosening them of resulted in very noticeable play. New bearings, and careful adjustment let me reduce play to well under 0.1mm, which was good enough for what I use the machine for.

[Gkkes]

From the start I want to learn how precise the machine is by installing a pen refill instead of a bit, and "drawing" the design on some reasonably thick card, double-sided to the sacrificial bed.
Comparing measurements will identify errors in my method, design, code in both path and depth and instill an understanding of exactly how the eagle interfaces with the mill.
This might also highlight the deficiencies in the 3020T and provide a before/after comparison.
Enjoying the learning curve and brain workout.
My eBay search is still operational.
Thanks for continuing advice.
Kev