V-Wheel carriage between four 1/2" EMT or PVC Pipe

thingiverse

After putting together the Mostly Printed CNC machine this summer, I've been thinking about other uses of Electrical Conduit Pipe (EMT). Testing whether it was possible to run a carriage with V-slot wheels using inexpensive EMT or PVC as the support and movement instead of using the V-Slot aluminum Extrusions got me excited. A simple carriage for use with Conduit and another one with PVC are included, along with some simple brackets to hold the pipe in place while testing. The result surprised me - it worked quite well. With the carriage offset more than when using V-Slot, adding another carriage on the other side of the pipe helps the bolts stay perpendicular to the carriage. Sixty-millimeter bolts are likely needed to make that work with 1/2" EMT, and I didn't have those available yet for testing. Four 1/2" EMT 1-meter long pipes weigh about five pounds three ounces total. You may need to play around with wheel offset dimensions to get the right fit for your setup. When longer bolts arrive to test a dual carriage, I'll know what those should be. A ten-foot piece of 1/2" conduit here costs about $2.50, making this idea's cost savings pretty clear if it works out. Using less expensive shower curtain wheels like the ones shown in this Thingiverse item: http://www.thingiverse.com/thing:1118344 is also a possibility. These have a 6mm ID instead of the 5mm used with V-Slot Wheels. I've added a set of plastic spacers to replace the extra six-millimeter spacer and three one-millimeter shims on all wheels, in addition to that. This idea works well with an idler pulley I'm using on a Delta printer too - there's an openscad file available for adjusting spacer size if your setup needs it differently. For the EMT Single carriage, M5x40mm bolts are used for the wheels, while for the 1/2" PVC Single carriage, M5x45mm bolts are likely needed instead. I've included two photos showing how to use the tapered spacer against the wheel and another one against the plastic carrier. Be sure that if you place the tapered spacer against the wheel, you use a diameter large enough not to interfere with the wheel's rolling motion - otherwise they won't move at all like happened initially when placing the larger diameter against them.