Making a focuser

Stans atm page

Adapted from the Crayford design

Making a Spider

The 14.5 I.S page

It took a couple of weeks of looking at different designs on the web to come up with an easy to build focuser.   It acually took about 4 hours to make this focuser and I did not have to buy anything, this was made from scrap materials, with common tools.

Fiberglass tubes

This design can be adapted hundreds of ways, The parts in this focuser are as follows. (1)-2-7/8" square of pvc (cut from the side of a pvc pipe) (1)-  1-1/4"L x1-1/2Id. pvc piece (1)- 1-1/4"Id,1-1/2 od x2"L pipe (or some pipe you can fit your eyepiece in and still fit loose in the 2"pipe). (1)piece 5/16"x1" automotive breakline. (1)piece 5/16"x1-1/4" auto breakline. (1) 1/4"x3-1/4 brass rod (1) piece 1/4 Id x1/2"L hose (1) spring (mine is a 4" carbourator return spring. (2) 3/4"x1-1/4"pieces of teflon,(I am pretty sure felt would work).. (1) 1/4"setscrew (1) Knob (4)  #8 x1/2" self tapping screws (points ground off) for base alignment. (4) #8 x3/4" self taping scerws to hold focuser on.

I filed a flatspot on the eyepiece reciever tube to keep it from turning and to keep from focusing too far and having the assembly fall out.

The base for the focuser is cut from the sides of a piece of 4" pvc pipe. It was heated in an oven till it got flexable, then hot pressed to my tube to give it the right shape. I then ground off the corners and tapered the edges with a bench grinder. A 2" hole was drilled into the base and the 1-1/2 id x 1-1/4L piece of pvc pipe was glued in with epoxy. I thicken my epoxy with flour to make it almost like a filler. I carfully heat the epoxy to get faster curing times.

The roller hole was made by drilling a 1/2" hole, then squaring it with a file. The shaft  slot was made with a file. The shaft is a 1/4" brass rod with a piece of hose glued on it, it uses steel breakline for bushings and a spring to hold everything. The black screws hold down the focuser and the stainless screws are for ajustment

Teflon pads are glued to the inside of the assembly

The stainless screws are screwed into the base and the  holes for the hold down screws are oversized to alow for alignment from imperfect gluing operations.

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