well, as usual i've been thinking about this homemade cnc router thing. thinking about what i can work with and what i am most familiar with. conclusion is: why not make the structure, guide supports out of plywood rather than the typical alluminum channel? laminating some pieces of plywood together would readily give me a much stiffer setup than many of the pipe or aluminum chanel ones i've seen online. plus, plywood would be much easier to work with. steel or aluminum pathways for the bearings would make it as durrable and smooth running as anything else. ok, so i could make a 5' by 10' plywood framed homemade cnc xyz router table. being cheap, i'd be using all thread for my leadscrews. can i get 10' allthread? I don't know. do i want a 10' long table in my basement. it would never be able to get out, and its difficult to take full peices to the basement. so what to do now you say. ahh the answer is so obvious. make a shorter table but keep the ends open to allow a full 4'x8' sheet to be cut in parts. so now i'm down to a 5'x3' table, a much more manageable structure, and improved stiffness for the amount of material needed.

my favorite place to look at pictures of this sort of stuff:
http://www.kleinbauer.com/

they tend to follow the milling machine model of z movement for the cutter and x-y movement for the workpiece. i'd rather have xyz movement of the cutter and a stationary workpiece. i always figure, when choosing which tool to use that its better to move the smaller lighter piece. ex. when cutting plywood, use a circular saw not a table saw. same here, if your workpiece is bigger than a couple square feet, move the tool instead.

having the z mounted on the y mounted on the x requires an added amount of stiffness to keep things in line and to prevent binding. oh, and what do you know using plywood i think i'll have a stiffer setup.

word to the wise: if you're reading this and you're not me. good luck understanding any of this.