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Hi Molly,
I used Teflon here, though in the case of a 4.5", or a 5" like yours, a piece of PVC cut from a flat surface from a PVC pipe cover would do just as well because the scopes are quite light.
For a scope like a 4.5" or 5", if you buy a strip of Teflon 15mm X 75mm, 3mm thick, you can then cut the necessary tabs you will need. I'd suggest you measure, drill and countersink the tabs before you cut them out. Use a hacksaw to cut and a stanley knife to tidy up the burs.
For the altitude bearings, four pieces, 15mm X 12mm is ample. The scope/brace box is so light that the 15lb rule will be difficult to aquire, as the these parts will struggle to top 10lb (4.5kg)! I'd suggest spacing the tabs at 90 degrees to 100 degrees to each other along the arc of the bearing cut-out. The orthodox 70 degrees done on big dobs makes the altitube movement too light and will be too sensitive.
For the azimuth bearing, three pieces 15mm X 15mm is enough.
I'm finalising an article for the iceman to go over to hopefully publish in the Projects and Articles section on this topic.
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