That is a good question. I have some large pieces of extruded ali for the two uprights, this stuff is 80mmX160mm and has internal webbing and a thick wall. I'll add an aluminium doubler for mounting the rails on. I can get these milled true with respect to the base on the mega sized milling machine in the department .
For the base I am still thinking, I really liked the egg box torsion style contruction but not sure how to go about it, this is one idea I had attached Not eggbox but I think it would work OK I think, the sides might be 80mmX40mm extruded ali and the cross-pieces 40X40mm. There would be a top and a bottom, the former t-slotted. Not sure I am getting much stiffness for the weight, I can't make it too heavy, my workshop is in the attic with a horrible little spiral staircase up to it. I would really like the webbing of the base to be made from say 5mm sheet upright and welded into a criss-cross but the welding is the problem in that I can't do it and the access to the joint lines would be limited anyway.
Other things I am stuck on is the gear ratio to the screws. Thanks to the new FAQ I can do the calcs and Mariss from gecko also posted info on matching these motors to a ballscrew however I am leaning towards accuracy so encoder choice and pulse rates all come into it, I am also not sure what I want. Then I wonder if I am really going to acheive any more accuracy than most due to the rolled screws.
The use of the machine other than general routing in wood and ali is mouldmaking and 3D milling jobs. I make propellers and such things and would like a good degree of accuracy so things can be made to fit together.
Generally confused but I now have time to work through the confusion.
Graham
p.s. Reason I have no cash is the 25W CO2 laser sat on my bench, another reason to finish the router! |