Original+TRO+Making+the+mount+and+tube+assembly

The spider was made at the end of July in a couple of evening's work. The mirror holder uses 6.5 inch diameter plastic pipe, threaded rod (M10) and wood. The 45 degree section of the secondary holder was cut by forming the rolled out shape on AutoCAD and wrapping round the tube. This was then marked and cut to shape. The back has a 3/4 ply disc inserted to hold the three threaded rods to allow for collimating. These pass through another 3/4 piece of ply with the springs between for adjustment. Wingnuts on the back of the outer section provided easy movement of the mirror. The outer disc has a hole cut in it which has a 12-inch long piece of threaded rod passing through the 2x2 inch square boss for holding the vanes for the spider. These are 3mm wallboard.

The top section was completed in a few days in the first weeks of August 1997. It has three rings of 3/4 ply, 36inchs in diameter with a 2inch rim. Two are sandwiched together for the base ring, which joins to the lower connecting rods. The top ring is the joined to the lower ring by 8x28mm diameter wooden dowels. The inside then has rolled hardboard to stiffen the structure and to provide a light shield for the secondary. The secondary mirror will be a 12x12 inch ex-photocopying mirror, which will be cut to shape (minor axis approx. 6.5 inches)

The bottom section was made of 4 pieces of 3/4 ply 36 inches wide and 24 inches deep. These where joined to make a 36 inch square box 2 foot deep. Prior to assembly of the box, 4 pieces of 2x1 inch baton where placed 7 inches back from the front edge of the tube to allow for fixing of a 35 inch square baffle with a 33 inch diameter hole cut central. This would also square up and strengthen the bottom box during assembly. 2x2 pieces 6 inches long were then fixed to the inside of the tube up to the back of the baffle. Large pieces of 5x3 with triangular corners were then fixed to the back corners of the box. These were then drilled through to accept 12mm threaded to hold the back plate and mirror cell in place. The back plate was 36 and 3/4 inch square and strengthened by 2x2 inch angle steel section across its back. The mirror cell adjusting bolts were then passed through the angle for extra strength. The top and bottom section were joined together by 1950mm long 32x44mm planed pieces of wood. The bottom end were drilled to accept 12mm coach bolts to fix to the top of the bottom box. The top end had 100x44x4mm aluminium plates rounded off at one end fixed to them by 4x6mm bolts. The rounded end was drilled to 10mm to fix the top section angle braces.

Telescope tube was first assembled on the 12 February 1998 at 0134hrs in the morning after a few hours of making the surrier truss pieces and finishing drilling the bottom box. It took some 20 mins to assemble and looked quit impressive stood on end with the top of the tube over 10 foot in the air. We then realised this was not going to be a small telescope!!

The rest of the mount was completed over the next week and all major components completed by the 21 February 1998 and assembled complete for the first time. The mount was very sturdy with a rap test of around 1.5 seconds. The Teflon bearings where not yet fitted and the altitude movement was a little stiff but moveable by one hand. The azimuth movement was similar but still required a smooth surface to run on (MDF at the time). The hard rubber wheels will be replaced by sealed roller bearings running on a harder surface and the altitude bearings will require Teflon to be added.

Cutting the altitude circle in half (2.25 inches thick, one for each side of the rocker box) was easy with a circular saw. These where then positioned onto the sides of the bottom box and orientated so as to allow for horizontal to zenith movement while keeping in contact with the Teflon bearing positions. (45 degree displacement)

Above image shows Geoff Regan with the tube assembly together for the first time (at about 1.30am). We then began to realise that this was not a small telescope!!! Above image shows me with the telescope together for the first time.

Original TRO Introduction and concept Original TRO Purchasing the blank and hoging out Original TRO Testing the curve for accuracy Original TRO Making the tools for grinding by hand Original TRO Evening out the irregularities left by rough grinding Original TRO Polishing and testing Original TRO Making the mount and tube assembly Original TRO Making the secondary flat Original TRO Aluminising the primary mirror Original TRO First light