The right ascension disk's periphery bearings are 1" diameter stainless steel in 1" pillow blocks.  The 'tire' for the r.a. disk is 1/8" thick x 3/4" wide aluminum.  I routered a groove down the middle lengthwise and have a 1/32" cable running down the slot to turnbuckles at the top of the disk to pull it tight.  There are three slightly oversize holes with wire brads nailed through to keep the tire on widthwise.  The brads are of my own construction from 3/32" diameter piano wire.  Initially tried actual wire brads, but they're too soft and bend too easy.

The dec. axis pillow blocks are bolted through to a length of aluminum angle beneath, and the large truncated triangle side pieces bolt to the vertical flange of that angle.  The load is therefor carried straight down to the gluelam at the south.