Hi all - in the process of building very first CNC machine - been lots of fun and learning. Most of the parts have already come in. Tomorrow I plan on getting the 30/60 extrusions ordered and cut to size. I have run into a little bit of a hiccup and was wondering how you pros deal with this. The supported rails and ball screw That I purchased are both exactly 900mm tip to tip. I am not sure but I think I read its not a good idea to mount the supported rails directly up flush against each end plate due to possible thermal expansion warping the machine. I have left a 20mm gap on either side of the supported rail. This leaves me with a situation where the ballscrew end mount does not make it to the end plate and is kinda left hovering.
Also if you could have a look at my design and give opinions on whats done right and what may need work. I know I probably should have used thicker aluminium flat bar - but I am budget constrained and managed to get a lot of 10mm thick - so I am hoping that will suffice if I brace the joints etc. All opinions very welcome ;-)
Attached please find an annotated picture from the CAD model which shows the issue clearly.
File ?my-cnc-final - SketchUp Make 2015-04-23 03-43-46.png?
Any advice - much appreciated.
Thanks
Mark