ASSEMBLING THE TELESCOPE:

Having made and tested your primary (main) mirror, now you have to assemble all the components. Having also known exact focal length of your mirror through focault testing (fl is half of radius of curvature), you also know the distance of the diagonal (secondary mirror, oval in shape) from the centre of the primary mirror. The diagonal has to be placed in the Telescope Tube in such a manner that after reflection, the image is crossing the Tube-wall by around 60/70mm or focuses at a point where you can view it through eyepiece inserted in the Focuser.

Suppose you have a Focuser whose height including its inner tube is 65mm. This inner tube after racking comes further up around 30 to 40mm. You have to place the secondary at a distance from the Primary Mirror that when the image beam is reflected from Primary, comes to the Secondary and is reflected upward, it should go inside this focuser tube to a distance so that a high power eyepiece, whichever you have, could focus the image easily and still some length is spare to move the focuser tube up and down i.e. it could go down around 10mm and go up around 30mm.

Here this distance is around 870mm from the centre of the Primary Mirror.

Speculam (assembling/putting Primary Mirror in its Cell): Take a round or in triangle shape wood plate (A) around 10mm thick and of 114mm diameter (equal to Mirror diameter which you have made) to hold Mirror and another slightly bigger wood disc (B) Base Plate of same thickness having 133/134mm diameter which will fit into the PVC pipe having 134mm inside diameter (Iron plates of 16 gauge or Aluminium plates of 12 gauge or 4 to 6mm thick may also be taken). This bigger disc will hold the 114mm dia (A) plate along with Mirror.

Place both plates A and B on top of each other, their centre coinciding. (fig.1 from left). Drill 3 holes of 5mm dia 120 degrees apart in both plates ( as shown down below in fig. 1 from left). All 3 holes in both plates should also coincide. Get the holes of B Base plate larger by around 8 or 9mm. Make a semi circular groove in exact centre of Plate A on the side facing B plate. This semi-circular groove be of the size to take in half width of round-head of 3/16 no. screw . Put three 3/16 (no.) counter-sink head screws (shown in fig 2 from left) one and a half inch long in the holes of Mirror A plate from the front side of A plate which will go into the holes of B plate.Tighten these with nuts, putting spring washer before the nuts.

Put around one and half a inch long round-head 3/16 number screw in the center of the Base plate B. The round head should be towards A plate and around 3/4" out from the Base Plate B (as shown in 2nd picture below). Tighten it by nuts and spring washers from both sides. This screw will ensure that Mirror is always in its center and while collimating there will be no lateral (up and down) motion.

Insert the 3 screws of A plate into the 3 holes of Base plate B and slightly tighten these by wing-nuts. As shown in the 2nd, 3rd and 4th picture. Ensure that the Base Plate B's central screw's round-head is half inside the central groove of plate A (see 2nd picture). Put some thick paper/rubber pad (around 1-2 mm) over the front side of Primary Mirror holder A plate which should cover three screws' counter-sink heads in such a manner that the heads and paper become parallel or paper should be slightly up. Carefully place Coated Primary Mirror over it. Secure the Mirror by 3 clips, as shown in pictures. The Mirror should neither be tight/pinched nor loose. That gap may be upto hair breadth.

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plate. Get the holes of B plate larger by 5mm. Insert 3 counter-sink head 0.1" machine screws in A plate and tighten these with spring washers and nuts. Araldite this A plate in center with the back of wooden disc of 24mm along with screws. Make a semi-circular groove or drill a 5mm hole in the center of wood rod so that a brass Dome Nut could go slightly inside and rest on the Iron plate A (see above picture).

Insert another iron plate B in the bent end of long 4.5" bolt 10mm inside from the corner and tighten with spring washers and nuts on both sides. Put one dome brass bolt at the corner of this bent bolt after the 2nd B plate and tighten it (see the picture above). Now, put the three screws of Araldited plate along with wood inside the three holes of 2nd B Plate so that the dome-nut is secured at the central hole of first plate A. Put wing nuts or normal nuts in these three screws (see the picture above).

Araldite your secondary coated mirror (diagonal) at the 45 degree cut face of wood.

Now you secondary-holder is ready and the secondary mirror araldited on wooden 45 degree face can be tilted in any direction with the help of Wing Nuts.

Paint the telescope-tube inside with black Asian/Shalimar black board paint and outside with grey, red or any dull colour

Put the speculam (whole mirror assembly (alongwith A, B plates and mirror with screws) in one corner of the Telescope Tube around one inch inside from one corner and secure it by three 3/4 inch long screws as shown in the pictures 2 and 3 above and down below.

help of proper nut-bolts. See that the Focuser's inner tube is centered over this hole (see above picture)

For putting the Diagonal make a 5mm hole in the Tube and near the focuser's hole at a place that roughly the secondary mirror is centered under the focuser's inner tube. Secure the 3/16 number 4.5" inch long screw of the diagonal assembly in this hole. You have to adjust this screw up and down, left and right so that the secondary mirror is centered in the Tube both laterally and horizontally or importantly optically centered with the Primary Mirror (see above middle pictures).

You can also fine-center the secondary mirror under the focuser's inner tube by drawing the secondary mirror assembly close or farther with the help of two nuts of B plates i.e. you can change the distance between B and A plates so that the secondary mirror is almost perfect in centre of the focuser's inner tube. Then with the help of 3 wing nuts behind the Primary Mirror, as shown in above pictures, you can also fine tune the optical center of secondary mirror with the optical centre of the Primary Mirror.

Having fixed Speculam, Secondary with holder and Focuser along with any one eyepiece over the telescope tube, now keep this telescope-tube over any circular pipe around its center to know the exact center of gravity. Upon knowing the position, make two 0.2" holes perpendicular to the Focuser or at points so that the Focuser becomes slighted titled (by around 10 degrees) towards the observer so that the observing is easy (see the picture at Tripod page). Secure two, one and half inch long 0.2" or 6mm thick slightly-round-head bolts in these holes. Put one washer each inside and outside the Tube and tighten with spring washers and nuts at outside the Tube.

Also put two eye bolts or finder-scope as mentioned in the Finder Scope page and shown in Tripod page.

Now, you have only to fix the Telescope Tube over the Tripod as shown in the Tripod page and collimate the optics.

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