Aligning the bed

The Z-probe was invaluable in helping me align the bed, making sure it's flat. I used the Z probe in 6 different positions along the front and back of the bed. Since these positions would not normally be used for milling (and I had a slightly oversized bed for my needs), I left the Z-probe holders in place permanently.

Measuring the Z-probe depth at each point allowed me to identify that the bed had about a 0.5mm delta in the X axis, and 0.2mm delta in the Y axis. This was expected, as I didn't have a nice way to ensure that everything was aligned, so having a total of 0.7mm difference was quite pleasing.

In order to align the bed, I bought some feeler gauges, and inserted them between the MDF of the bed and the 2020 aluminium box section. Unfortunately, it wasn't simply a matter of using their relative heights; it did take a bit of trial and error.

Eventually, I was able to get the bed to be aligned to within 0.01mm - which is the limit of the accuracy of the feeler gauges. This should be good enough for my needs!

Alignment pins

In order to allow me to quickly position work on the bed, I drilled some 3mm holes at set points. Metal dowel pins can be inserted in the bed to align the material to be worked on. I had a number of different things I wanted to work on:

• PCBs
  1. 160 x 100mm 'Eurocard'
  2. 223 x 100mm
  3. 223 x 160mm
• Aluminium plate
  1. 1U (487 x 44.5mm)
  2. 2U (487 x 89.0mm)
  3. 3U (487 x 123.5mm)

I had various pre-cut 1U panels (and I got some made from aluminium plate to experiment with) - but I found that their widths weren't all 19", so I had to make 3 different lengths so that the work could be accommodated without moving.

Holes

Note that this is using some 18mm long dowel pins; they have since been replaced with 12mm pins so they are less likely to interfere with the milling / drill bit.

Mounting a 1U panel

This is one of the blanks I got cut from aluminium plate, held securely in place with some dowel pins

Mounting a 160x100 PCB

The pins simply get moved to different places - where they are marked - to fit the board to be drilled / milled.