I've been working on a robotic scroll saw that will use an XY table, and a scroll saw equiped with a spiral blade to allow a computer to cut out 2D shapes. I have the scroll saw, so I've been focusing on building the XY table. It'll have about 18" inches of travel in either direction. I'm using the guts of some old DecWriter II's as the main source of parts. So far I've built the lower stage consisting of two hardened steel rods, a pair of linear bearings, a threaded lead screw, and a tensioned cable that goes around 8 small stainless steel pulleys. I welded up some brackets to hold the shafts, and pulleys, and bolted the whole mess to a piece of plywood. The cross member is made of 2" angle. The second stage will sit on top of the first, and consists of a similar set up with the rods much closer together, and no pulleys.
I had originally intended this to be a 1 weekend project, because I already had build some stepper driver electronics for my CNC lathe conversion. It ended up taking two weekends to put the first stage together (mostly due to the complexity of the pully arrangement, and because I decided to make the mounting brackets look nice, etc.) Here's a close up of the bracket and the coupling that connects the stepper to the drive shaft. Saddly, when I fired up the bottom stage under computer control I realized that the 5-phase stepper I was just too slow. You could watch the cross member move, but you had to be watching pretty carefully. So now the project has been on a back burner for a couple of months until I get around to hacking up a new flavor of motor driver for this new project.
