So one of the industrial plants I work in has scrapped a HUGE amount of aluminum T-slot extrusion and I have free reign over picking through it, the only rule is that it has to hit the dumpster first before I can load it into my truck. Some of it is bent, some of it has been crushed, but there is a LOT of it that is in perfectly fine condition, just odd lengths and sizes and not all of it matches.
Some of it is 50mm x 50mm, and some of it is 100mm x 100mm, it's all some generic version of 80/20's stuff but I have no idea what brand. First thought was finally I'll build that CNC plasma table...but I don't have enough power in my workshop to run a 50A plasma, and while the plasma would be great for cutting 3/8" steel exhaust flanges and bracketry, it would do me little good for aluminum plate that I'd need to cut, most of which is 3/8" thick or thicker.
Now I'm looking at building a 24" x 36" CNC gantry mill, thus I'd be capable of a lot more flexible work than the plasma, but ultimately at a much slower cut rate and higher per-cut cost. The advantage is less outright power required, as I could get away with a MUCH less powerful air compressor to run the mist coolant. Currently the entire shop has 240V 30A service...when I run the TIG welder on a heavy aluminum casting the lights used to dim a bit before I converted to all LED lighting.
The new shop won't be built for 5 years-at which time I'll have 200A service to the shop and dedicated shop air. Until then, I'm stuck with what I have.
Given that I have absolutely no issues with welding together my frame instead of bolting, and have been doing plate fabrications (brackets, flanges, etc) for over a decade with reciprocating saws and files, what kind of advantages can I get from using this free material vs buying steel channel and tubing? What kind of disadvantages? I do plan to mass-load the base with sand or machinery grout to help dampen vibration and the gantry will ride across the narrow axis to help improve rigidity.
Since there is a crap-ton more of the 50mm stuff, I plan to stack two of them side by side and stitch weld them together into a 100mm x 50mm section for the short spans in the base, if I run out of 100mm section. I've done custom auto frames from scratch, so I'm familiar with how to build frames and frame-like structures and the techniques needed to keep things square and true.
Next round of questions is what size of 4-way linear rails and steppers (I'm thinking nema 23 425oz steppers would be OK) should I be planning around.