baffled

I am building a couple of aluminum refractor tubes for 6" lenses. I am practically ready to paint and put the lenses in, with one exception. I am thoroughly baffled on how to baffle the tubes. Can anyone point me to someone who can make precise donut shaped baffles which are produced to fit my tubes here? (They are about 5.75" inner diameter.) Thanks. Mike

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Mike;
Those are great looking tubes, and are both of those astrophysics focusers? I also need to build a new tube for an old 4" F15. Could you tell us where you got your material for the tubes? Did you have the dewshields and the hubs machined or were they available over the counter? thank you, Bill

I had a similar problem. I have a 5" F7.2 Petzval military surplus refractor. The scope has a fully corrected 5" diameter field so I didn't want to use conventional baffling for an eyepiece. The inside of the tube was not exactly round where it was not machined for lens cells.

I used a CAD program to do ray traces from the outer edge of the objective to the opposite side of the tube to the first lens of the corrector. It turned out that to get a full 5" diameter light path I needed about a dozen baffles spaced about 2" apart.

I made the baffles out of some black paper that was similar to the material used for file folders except for the color. I cut the baffles with a I.D. just under 5" and an odd. of about 6". I cut the circles with a compass that had a razor blade rather than a pen. I used 2" strips of medium density black foam between the baffles. The foam strips were cut so the ends just touch when they are inside the tube. The strips have enough stiffness stay against the side of the tube. Assembly is simple, you just slide in a strip followed by a ring and repeat until they are all in place.

I've had the scope for 6 years and the baffles have not given me any problems. The baffles work very well and the the scope has excellent contrast. Someday if ever get a suitable mount, I'd like to try taking a 4" x 5" photograph with it. It certainly is an interesting design. The last lens in like a soup bowl with a 1 3/8" sagita. To use it as a telescope I had to cut 6" off the original tube and install a focuser. The focuser extends 1" into the field lens when it is fully retracted.