Desktop CNC 'Thing'

[Misterg]

The ganty was fabricated out of 100 x 50 x 3 hollow section steel. Thinner than I wanted, but I thought it might be OK if I welded on some thicker pads where the linear rails would fit, and possibly filled it with sand, or something to stop it ringing if that proved to be a problem.

I tacked some 25 x 25 x 3 angle to the front to square up the corners and give something to secure the linear rails to.




I was only going to stitch weld it at ~25mm intervals, but cocked up my marking out and ended up with the tack welds in the spaces between stitches - it looked cr*p so I filled in the blanks and they ended up fully welded.





The hole in the top is there in case I decide to try filling the fabrication with something (sand) at some point in the future. The hole with a sleeve welded into it is for access to the screws on the back of the Z axis cars, and the four extra holes in the face are to allow any filling to flow into the uprights.

The best I could scrounge for some uprights was some 80 x 40 x 3 which were notched to fit around the cross beam (I had it in my head that the joints would be more rigid if they spanned two faces of the box)






I hadn't designed the bottom half of the machine at this point, so just made some flanges that could be welded to whatever I ended up with later:





At this point, the face of the gantry was 0.3mm out of plane (judged against the glass plate). I laid it on its back, got it level and masked it off before slathering the rail beds with slow setting epoxy.



I put a layer of cling film over the glass plate and carefully lowered onto the epoxy, squidging it out.



Once I was reasonably confident that it wouldn't slide off onto the floor, I walked away and left it for a day.

Getting the glass to release was a bit of a battle - I thought that they were permanently joined at one point. It eventually came apart and after a clean-up, it seems to have worked quite well: