Telescope Tube Rings


After looking for large tube rings I decided to make my own.  Yes, I would love rotating rings from Parallax Instruments but….  I use maple for the rings.  I cut a bunch of 1.5 inch pieces of 3/4 inch x about 4 ft long maple and glues them together to make a 1.5 inch thick board (about 6 inches wide).  I then cut, with my table saw, pieces that were about 1/16 inch thick (by 1.5 inches wide).  I cut enough strips to make the thickness I wanted (about 1 inch).  A good bandsaw would have helped because I lost a lot of wood due to the table saw blade kerf.  I made a jig to bend the pieces and hold them in a semi-circle.  The jig was just several layers of plywood screwed together.  The jig had 2 parts.  One was a board with a semicircle cut out of it.  The radius of the semicircle corresponded to the outside radius of my deired tube ring.  The other part of the jig was just a semicircle this the radius corresponding the the desired inside radius of the tube ring.  I glued the strips as fast as I could then stacked them together.  The stack went between the jig pieces and then I used a ratchet strap to ratchet the semicircle into the board witht he semicircle opening.  This pressed the strips into a semicircle.  My strips were long enough to allow for the obvious unequal finishing radii of each strip.  I made 4 sets, cut them appropriately, sanded, varnished and fastened them together with a hinge at on joint and a toggle clamp (LT-40323SS, www.the toggleclampstore.com) at the other.  I used a Losmandy dovetail plate and radius bars (Losmandy.com) on one side and a carbon fiber/plywood plate on the other.

These pictures are of my tube rings for my 8 inch carbon fiber tube Newtonian.  The top plate (first picture) is made from plywood laminated with carbon fiber.