For me the only way to be sure is to use as much extrusions as possible and putting for example that Alu slab on top to ensure maximum possible rigidity for the base of the machine.
After that it will be a matter of testing the precision and limits of the machine. A true Trial and Error process if you like.
Given the size and what I hope to do with the machine, I think I will be ok, but far to early to say it for sure.
Also 2 pictures of the fasteners.. Those alone are a real nice piece of work. Spring loaded balls in it so you can easily push them in and move them to position. Once there, they'll stay still and very easy to fasten a bracket or anything.
Got hundreds of them with 3 or 4 different screw sizes.
Screws, of course I got pretty much the same amount.
So given all this, I can build a machine as strong as possible, but like to keep that within reason of course.
If this first build will be good, I'm all for it to start another couple of builds and put them up for sale, as I have plenty of extrusions, aluminium parts and fittings to do just that.
Cheers,
Luc
ok...pictures: