Finally the build starts in earnest with the MPCNC basic frame.
So, here we go. I have printed all the plastic parts, and bought the EMT conduit and most of the hardware. It’s time to actually start building the Mostly Printed CNC machine. Based on my desire for a 24 by 18 inch work area, the guide rail structure needs to be 35 by 29 inches. The MPCNC basic frame is the structure upon which everything else sits. The total cost of this frame was around CDN$25, mostly for the 3/4 inch steel conduit.
A friend loaned me his Husky tube cutter, shown lower right. This is a relatively inexpensive cutter, but appears to be solidly built. It is able to cut copper, brass, aluminum and thin-wall conduit. Setup required clamping the tube to the workbench and marking the length of the cut with a pencil on the tube. The cutter then fits over the tube and gets gradually screwed down to increase the depth of cut. You then rotate the cutter around the pipe. Getting the first layers of the cut right is important to line the cutter up. It took me around 20-25 turns around the pipe for each perfect cut.
The whole process to make 12 lengths of conduit took about 15 minutes. This included the rule “measure three times because you only cut once!”
As previously described, I had sanded down the plastic corner blocks to properly fit the round conduit. I also had to file out several of the holes for the insert nuts needed to hold down the plastic lock rail for the top pipe.
MPCNC Basic Frame – No Waste
As it turned out, I was able to cut down the two lengths of ten foot conduit without any waste. Pipe #1 cut down into three 35” long axis rails and three 5” vertical mounts. Pipe #2 cut down into three 29” short axis rails, two 14” Z-axis rails and one 5” vertical mount. This accounts for the 120” length of each pipe. Since you lose a tiny bit of pipe with each cut (not much) I decided to sacrifice a bit of length in the vertical mount pieces.
The Husky cutter did such a good job, the cut ends were quite smooth and very little reaming was required.