Updating an old CNC engraver
A few weeks ago Mark went above and beyond and donated an old Domiteaux Powerbase CNC engraving machine to the Hackerspace. It’s a late 1980’s vintage CNC engraver and came complete with the original controller and an ancient laptop to run it. The original controller included ROM cartridges that contained the fonts and symbols, and a parallel interface. It has a 14″ x 16″ work area, a diamond engraving head and a rotary cutting tool driving but a belt / motor set up. The machine has an acme screw X / Y table driven by a pair of sizeable steppers, a third access which is pneumatic and is only capable of binary up or down control. There is also a 4th rotary access below the working surface for round items. The original software could not be located so work has begun to retrofit it with a modern controller and USB interface.
We have a number of planned upgrades for the machine, including adding a proper Z axis and replacing the belt motor setup with a dremel or similar rotary tool to create a 3 axis mill. The Z axis is based on the Ponoko shapeoko mill (http://www.shapeoko.com/wiki/index.php/Main_Page). We have a decent length of maker slide and v groove wheels with bearings (also donated by Mark, really cannot express how thankful we are for everything).
A good deal of progress has been made making a replacement controller. The best setup we have so far is an arduino uno running GRBL (https://github.com/grbl/grbl) and a PC running GCode Sender (https://github.com/winder/Universal-G-Code-Sender) and have had decent results. Using this setup we have engraved a handful of PCBs and some acrylic with good results. We are currently wusing a stepper motor controller that was donated with the machine, and while functional it has some very interesting (read borderline dangerous) wiring so efforts are underway to develop a new motor controller built around the ST L6480 (http://www.st.com/internet/analog/product/253950.jsp) we are working on. There will be a number of updates as we add more features to the machine and develop the stepper motor controller.
The Z axis we are working on used a 1/4″ thick piece of polycarbonate which proved too flexible in practice to be a good mount. We purchased a 1/4″ thick piece of steel from a local supplier to replace the polycarbonate.