I've welded the construction today... just to figure out how to get it off my welding table and I'll send it to machining. It's around 200kg already.
I didn't weld it fully and I did jump all over the place so the frame didn't heat up much at all. I'll fill the gaps in the weld with bondo so I can fill the tubes with sand later.
I actually thought about 2:1 reduction on the Y axis where I'll have two 8.5Nm motors - motors spinning at 500rpm and the screw at 1000rpm. Or at least that's what I thought about doing with a lighter gantry. I haven't done any calculations yet so I'll do that down the road.
Servos are out of my budget right now. These 8.5Nm steppers are $150 and the cheapest servos I could find are over $250 for a 400w one.
How do you compare the power of servo vs stepper motor? Is 400w servo more powerfull than a 8.5 stepper?
Yes, the red line on that chart is for my motor. That's why I wanted to reduce it 2:1.
Gosh! So many questions. One more; Would filling Y axis beams with concrete stiffen them up by any significant amount? I would add those glass fibers to the concrete as well. Or should I just stick with sand and cry because I didn't use heavier tube? The tube is 120x80x4mm with 6mm flat bar welded on top.