Hello, all! I am starting to build a 32" x 60" CNC router table. I may be going about this in an unconventional way, because I am plunging in with construction without having every last detail engineered out to the Nth degree. Many of the "build logs" here could be perhaps called "completion logs", in that they show a finished result in their first entry. Not this one! That said, I do have a few givens and druthers established.
1) I am using an existing laminate-clad tabletop as my starting point. I got this massive panel for a song at Construction Junction, a local building-materials recycling center. I've seen a ton of table designs, and even some "finished" tables, that had no work surface! Yes, I can understand that a CNC router table's work surface may suffer a crash now and again, but I'm willing to live with that for this go-round. This is actually my second project start. I got a good start on a Seventh Sojurn, (John Kleinbauer design,) but I concluded that it was going to be insufficiently rigid for my work. Plus it needs a gazillion parts! Anybody want to buy a "kit"?
2) The table will have a moving wrap-around gantry, using the 1530 series of aluminum extrusions by made by 80/20 Inc. I am NOT going to build the whole table with this stuff, due to the expense involved. Only the gantry and the supports for the axis drive screws will be 80/20. Even that material will be obtained via "80/20 Garage Sale", their eBay outlet for overstocks and out-of-spec materials. I do have access to a metal-cutting bandsaw at work, which will allow me to gang-cut a pair of 33" sections for the gantry, hopefully ensuring uniform length where that is important.
3) I will be using the linear bearings offered by Ahren Johnson at CNCRouterParts . These things are dynamite! Ahren's system is based on using 1/4" thick metal strip stock as the rail. I'm using 1018 cold rolled steel, a pair of 3" wide strips for the X axis rails. Ahren's system needs a minimum 4" wide strip for the single rail used on the Y and Z axis, I may go wider here. Ahren's carriages and motor mounts should GREATLY simplify the build, it looks like an EXCELLENT value in the old "time versus money" tradeoff.
4) Stepper motors and Gecko G201 drives are already in hand. Control software will be the open-source EMC.
Here's a sketch of the way the tabletop, a 2x4 spacer, and the X axis rails are going together. Having the carriages "underslung" this way seems likely to keep most of the sawdust away, we will see. I have the front X rail already in place. When I drill the mounting holes for the rear X rail, I intend to elongate the holes so that I can adjust that rail for proper distance between. (In other words, I can "preload" that back rail once the gantry is assembled.)