Siff' Build Log

[Jonathan]

Will be welded to an aluminium frame when complete

Why aluminium? Will be interested to see it welded ...

The Z axis isn't completely finished yet..

Good, as it wont work like that!

Y-axis: You need to have the 4 plates that make up the 'box' round the linear bearings configured such that the plates with the bearings on can be adjusted to get the bearings precisely parallel. Look how I did it ... just don't copy my mistake - making two of the plates 10mm too short! At the moment it relies on the two plates in the YZ plane being machined very very accurately which just isn't going to happen.

X-axis: End supports for the ballscrews look a bit bendy? Remember that all the cutting force in the X direction will be resisted by those plates, so they want to be strong to stop the tool deflecting much. That's why I made mine the odd looking shape out of bar. The easiest solution I can think of is to replace them with box section then put a smaller plate/disc on that to mount the bearing. Have the holes slotted on both so you can align the ballscrews.
If you rotate the ballnuts by 90° you can get the ballscrews slightly closer to the tool...probably not significant.

The way your Y-axis box section is mounted to the X-axis is a bit bendy as the vertical plates only have a line contact with the X-axis bearings. That's why I used box section...

You could get the gantry even further down? Debatable if it's worthwhile.

Other than that looks good (but obviously I'm going to say that as you copied mine )