Angle-Iron bearings and Z-axis

Angle Iron's with skate bearings mounted using bolts

I decided that a full set of 3 bearings at 120 degree intervals would take too much alignment and precision so I fell back to the tried and true home-brew DIY pipe and bearing system that uses 90 degree angle iron with skate bearings bolted to it. I used steel angle iron that is 1/8 inch thick and 3/4 inches wide. It cost me $11.23 for a four foot length at my local (over-priced) hardware store. I also purchased eight 1/4 inch bolts, nuts, and nylon lock nuts to hold my bearings for $8.48. (If you purchased bulk boxes the hardware cost would be much cheaper!)

Note that skate bearings have an interior diameter of 8mm which is very close to a 5/16 bolt, but I’m using 1/4 inch bolts and a plastic spacer that I got from disassembling a pair of in-line skates. I had to use a rotary tool with a cutting disk to shorten the plastic spacers to make the nuts clamp down onto the bearings. If you do not have a ready supply of plastic spacers, simply buy 5/16 bolts instead, and wrap the bolt with a turn of plastic tape to get them all the way up to 8mm. With my 1/4 inch bolts, I drilled the holes centered between 5/16 and 3/8 of an inch from the outside edge of the 3/4inch angle iron.

I cut the back plate, pipe supports, cart, and bearing supports from a single piece of 3/4 inch MDF board purchased from the IKEA as-is room for $1. The back plate is 11 inches wide by 12inches high. (The black pipes are 12 inches long.) At the top and bottom of the back plate I have cut out 3 inch tall (by 11 inches wide) pieces of MDF that will support my two black pipes. The pipes have about 1 inch of thread on each end, leaving 10 to 10.5 inches of usable travel space. I want the cart to have at least five inches of travel, so I made it and the angle-iron bearing holders 5 inches long. I also cut out two 5 inch by 2 inch pieces of MDF that mount to the back of the cart to support the bearings. When cutting (imprcisely) with my jig-saw, I made sure that I used factory edges of the MDF when butting pieces together, so that my badly tilting jigsawed edges would not throw my 90 degree angles out of alignment.