Quote Originally Posted by routercnc View Post
Hi Chaz,

If you look at my design the side plates are braced back to the main Y axis assembly with effectively triangular structures. There is also a closer plate (see Y axis picture) to create a local box structure, which also provides stiffness for the Y ballscrew to connect to. On your design some triangular bracing pieces could work with a notch / clearance area at the inside corner to clear the ballscrew.

I thought alot about the spindle clamping and problems with keeping the rails aligned. In the end the spindle clamp is quite small, and the plate on the bottom surface is fixed (the transparent piece in the last picture), plus the front plate above the spindle is also fixed. This should keep the rails aligned whilst adjusting / clamping the spindle. Look at the last picture I posted for my thoughts on how to do it.

I drew loads of single and twin Z axis ballscrew arrangements but could not get a compact package with twin screws, so after agonising over it went back to single which has the smallest offset from the centre line I could achieve.

As for the Z axis bearings on the dmg machine - I don't know this for a fact but I can't see any Z rails so my conclusion is that is runs on a finely ground flat surface on the hexagon faces - bit like the ways on a mill / lathe but flat and trapped on all sides. You can see some sort of pre-load screw(?) or oiling point so perhaps it also has a film of high pressure oil in there like an engine crank/big end. Really just guessing here so would welcome thoughts from others on this. Either way, probably not a DIY solution.
Thanks. I think you might be 100% correct, perhaps its a 'perfect' fit solution - would be lovely.

Taking some inspiration from this thread, gantry design with epoxy. (Dutch thread). http://www.cnczone.nl/viewtopic.php?f=8&t=8410



Look at the speed on this - https://www.youtube.com/watch?v=rtJ3MGSM030 and it looks fairly rigid.



This also looks interesting -