Classes > Mechanical Design
For this class Raquel and me are working together in the project. Our idea is to take the Mantis 9 CNC, and first, convert it to metrical units, and then make some parts at the fablab instead of buying them. We also wanted to try some cheaper alternatives (like threaded rods instead of lead screws), and some nicer parts (like linear bearings instead of bronze bushings).
So we started to think in the changes we wanted to make, and adapting the CAD design to metric units. 10mm MDF instead of 1/2", 8mm precision rods instead of .375". 3/4/5mm holes, etc. Then as we wanted to use standard 8mm threaded rods for the movement of the axis (8mm threaded rods have an advance of 1.25mm each turn, so with a 200 step stepper motor, we have 1.25/200 = 0.0625mm precision), we added holes for 608 bearings at the end of the axis to minimize vibrations. Then we milled the wood parts.
Then we assembled the frame and tested our design. We discovered some flaws in the original CAD file, and also in our modified parts, so we fixed the design, milled the wrong parts again, and assembled everything.
After chossing the parts we wanted to use (precision rods, lm8uu linear bearings, 608 bearings, motors, etc), we ordered them but at the time of this writing they have not arrived yet, so we are stuck at this point. So we started also to design/adapt some of the 3D printed parts we wanted to use. With the experience I gained building my RepRap Prusa, I knew some really nice designs for linear bearings holders, shaft couplers, etc, so we downloaded and printed some stuff from thingiverse, so we just had to design one part. In this picture you can see the lm8uu linear bearing holder and the 5mm stepper shaft to 8mm threaded rod coupler.
When we finish the build and test everything works fine, we'll upload all the CAD files and the bill of materials used.