I hope this is not like the “have you guys thought about filling the tubes with concrete?” question, but I guess that it might very well be, so sorry for that in advance
I’m reading the importance of having the stiffest Z axis, and the easiest way to achieve that is of course by lowering the Z axis. From what I understand, strengtht of the conduit is mainly determined by the wall thickness and diameter of the conduit. Have you thought about or tried to add a tight 3D printed “sleeve” over the legs’ conduit to stiffen them, so the sleeve adds to the wall thickness and diameter of the conduit? That sounds like an inexpensive and fun way to stiffen the legs; of course you’d still have to think about the gantry, but still.
HAHAHhahah, you have been reading a few posts I see!
I think I understand what you are asking. A better way are corner braces. There are a few designs for that out there. Take that a step further and you can mount the bottom corners directly onto the table frame, kinda like all the other small CNC’s out there and just have the table top move down.
From the ones I have built and the few others I have seen anything below 3.5"-4" have no leg issues. There are four legs so the load is spread. Anything above that and I still don’t think the legs are the weak link but they do benefit from bracing or other means of support. All depends on the load/use case. The two Z rails transfer there load to the two gantry rails which then transfer to 4 outer rails and then four legs. I have one small part revision coming that might help a bit but nothing crazy
From what I understand it’s not so much the long legs that affect the overall stiffness, it’s the center gantry height. Better might be to go with a four tube redesign to keep it from pivoting under side pressure maybe.
