Xzero Raptor CNC build - linear rail and ballscrew selection

[Mattia]

Thanks Andy!

To spice things up and help draw some interest, here are a few shots of what I have - I've put together the gantry and base (just bolted it up, no loctite, no attempt to really level or line things up) just to get a sense of the size of the whole machine, and to get accurate measurements of the clearance between the 8080 profile and the gantry sides to figure out the required linear rail bits and pieces. Once I've got a little further down the road I may start a build log to document things for my future self and simply for fun, and to get some input if/when I get stuck along the way.







The ballnut housing has a 40mm diameter hole, which suggests a 25mm leadscrew to me. That would line everything up with the machined holes in the endplates. Overkill, perhaps, but what would the major downside be other than the need for a lot more power? I need to dig up all the other bits and pieces and pre-assemble the Y and Z axes to see if I even have all the required hardware for mounting everything. If not, that's going to take some interesting reverse-engineering, or re-engineering. The backing plate and uprights on the gantry are milled aluminium, the base (which the ballnut housing is attached to) is 2020 profile, bolted in. Being a woodworker, I'm mostly impressed by how heavy things made of metal end up being. The plan (and mounting bits and pieces) is to fit a Teknomotor electrospindle (2.0 or 2.2kw), which weighs a good 8kg. The Z and Y axis run on 20mm HGR rails with 2 'long' carriages (50mm bolt spacing) per axis, the gantry runs on 20mm rails with 4 'short' carriages (36mm bolt spacing). The Y-axis ballscrew seems to be a 1610 with supported bearings on both ends, the Z-axis bottom is unsupported. The machine is very similar to this one, which is a slightly different variant by the same builder/designer:

https://www.youtube.com/watch?v=9SG_6aKASUU

I've seen some references to improved Z-axis designs over something like this, but I figure I"ll start with what it was designed to do, as I know quite a few guitar makers who have done well with this machine. For now I'll likely direct drive the axes and consider geared reduction if I run into limitiations/want to upgrade things, once I've gotten it all up and running...