Over the past few months, I had been collecting all the materials for my new project, the movable gantry cnc machine and I felt that I was ready now to begin the actual fabrication work.
First, I had to design the machine. On my previous project, I could only do it in 2D. In this new project, I was determined to learn how to use autocad in 3D. After spending some time learning and trying out the various commands in the software, I managed to come out with a reasonable 3D drawing which I could use for my construction.
The materials that I had collected for use as the body of the machine were MDF and wood. I had also some round rods with their own linear bearings, and some stepper motors. I bought the required bolts and nuts, ball bearings, timing belts, and stepper motor drivers. The wood, MDF pieces and round rods were of particular dimensions. I had to work around these dimensions in order to optimize my design.
The design was essentially using the round rod and linear bearings for guiding the x, y, and z axis to move in straight parallel lines.
I had added in ball bearings that would roll on aluminium strips which rested against the wooden frames in order to take up the weight of the assemblies so that the round rods would not be flexing too much under these weights. This arrangement was for the x and y axes only.
The z axis would be just like my previously constructed movable bed cnc machine, complete with a counterweight. This arrangement was proven to work before and I suppose it should work this time too.
Fabricating the wood and MDF pieces posed their own problems, especially when I did not have accurate machine tools. I only had hand tools.
The result of cutting by eye-balling resulted in gaps between the matching surfaces of the pieces. However, these were later rectified by careful removal of high and wrongly cut areas in the touch-ups.
Eventually, the various pieces were bolted in place within acceptable limits.
The fabrication of the fixed bed was thus considered completed at this time. My next tasks would involve fitting in the movable gantry and its assembly.