Brent's Astronomy Pages - Deep Sky Objects

80mm homemade refractor:

Additional Pictures showing more details of the "Crayford Style" focuser, and the "Lens Cell" Nylon screws at 120 degrees hold the lens in place. Outer ring was cut from 3" PVC pipe using a compound miter saw. Focuser before being painted.
I decided to make a homemade refractor this winter. I used an 80mm X 560mm fl objective lens from Surplus Shed. The objective came uncoated and uncemented. I air-spaced the flint and crown. Also included is PVC schedule-40 and schedule-80 plumbing parts, bearings from old DLT tape cartridges, some nylon machine screws, a dovetail plate from my CG5 mount, craft foam from Michaels, spray-on bed-liner, and an old worm gear drive from the Meade DS series.
The focuser is a crawford style focuser. The key components are two PVC couplers epoxied together, four bearings, and the worm gear with the worm filed smooth. The nylon screw on top is a locking screw, the one on the bottom adds pressure to the shaft. Schedule-80 gray PVC was used for the eyepiece holder. I left the gear on the Meade worm gear. I plan to add a focus motor in the future.
I sketched out the light path and added 3 baffles using black craft foam (~1/4 in thick). The front half of the tube is lined with thick felt paper.