Just finished the prototype using PVC stormwater fittings.
The focuser fits just nicely inside 90mm stormwater pipe and is held in place with a couple of self tappers as it isn't a push fit.
The objective holder is a perfect fit inside a 100mm Pad Repair fitting. A 100x90 reducing bush is stacked on the other end. The ridge the pipe normally butts onto was removed with a file and a bit of work with a scraper took enough pvc off the inside to let a 90mm pipe slide through. At present the two outer fittings are held together with gaffer tape, might glue them later.
The tube just slides through the ridge on the inside of the pad repair fitting so the tubes remain parallel as they are slid in and out. The inner tube initially goes right down so its end contacts the objective housing.
The outer tube is 245mm from the end of the objective housing to the end of the reducer fitting. After a bit of trimming and testing the inner tube was cut down to 260mm. Thats a trifle short but by sliding the inner out a bit the best length can be arrived at.
Materials cost so far $20, 2hrs of assembly.
First light is tonight
