[boydage]

I have an old tested and tried machine. I am building a new Z Axis for it to carry a spindle that is 12kg instead of the 6kg 2.2 baby I smoked a few weeks ago. The machine itself is pretty heavy, the gantry is 6mm alloy plate screwed down onto a 300mm x 80mm LVL timber beam. Its great.

The Z axis. I am going to go for a 300mm travel and have kept the SBR20 rails at 600mm length to keep good space between the linear guides.

My question is the back plate, and the plate I will screw the spindle onto (in green on the pic). Thinking I will just use 10mm x 200mm 6061 extrusion. Is that too light in duty?

The only other option is to go 16mm 5083 that will not be as flat as the 6061 so once I have machined it flat will only probably be 15mm. Still 50% more in size.

Open to thoughts on what I should use here. I am quite confident the 10mm 6061 will be very rigid - but will it be enough? We only want to do things once huh. The diagram attached is a build drawing. I am wanting a good rigid machine to cut alloy. The spindle is a 4.5kw aircooled beast of a thing..... I think I am in love with it. But thats another story.