10inch Newtonian Part 5 - The Tube Cradle

A newtonian telescope mounted on an equatorial mount without a means of rotating the focuser position to a comfortable position is simply a pain in the neck.

I decided to make a pair of opposing tube rings to locate the tube and have the tube turn on them thus preserving the finish of the tube from scratches and scuffs. I purchased two slabs of 325x325x25 aluminium and screwed them together so they could be bandsawed as a unit. I took the assembly off the the local saw doctor and had him make me a new bandsaw blade first passing the saw blade through a starter hole before welding and dressing. I fitted the saw blade to my old saw and had the inside cut out in 20 minutes, before cutting the blade and fitting a new blade to cut the outside.

Incidently, my old saw has quite a history as it was manufactured be Walker-Turner Company in Plainfield NJ and served with the US Army in WW2. Somehow it made it's way to New Zealand and my father-in-Law found it on the scrap heap in the mid 50's. He did her up and it served him for years powered be an old motor scrounged from someplace. He gave it to me 4 years ago and I have repaired the blade tensioner and has served me well and she eats timber, plywood, plastic and aluminium with gusto although 2inch thick aluminium makes her grunt a bit.... hehehehe.

The cradle itself was made from laminated strips of the same 1.5mm thick ply that the tube was made from and the first stage of laminating was to apply four thicknesses of ply using a tube ring as a former. The lengthened hose clamps came in handy again to clamp each lamination while the glue dried.

The lower half was laminated with 4 thicknesses of ply and cut and fitted blocks of 25mm ply and clamped as shown.

Another 4 layers of ply applied to the outside and clamped and wedged as shown.

Removing the aluminium rings allowed me to plane and sand the assembly and to fit tree-nails (trunnuls) on the skew to pin the the assembly together.

The finished cradle with it's first coat of marine spar varnish. Note the darker circles. These are more tree-nails that add strength to the ply and allow propper grip for brass wood screws, rather than fit the screws into end grain of the ply.