| DIY Wedge (For Piers) |
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Warning: this design is not suitable for a tripod without extension of the bottom (Tripod) plate to adjust the centre of gravity.
Introduction
A wedge is a device placed under the base of an altitude/azimuth (Alt/Az) telescope, which changes the angle at which it is mounted to paralell the earths axis. This "Polar" alignment facilitates accurate tracking of the stars to counteract the rotational movement of the earth for long exposure photography.
Materials:
2 square plates of 10 to 20mm thick aluminium plate (size depends on your scope base) lets say 250mm square for example
2 pieces of aluminium flat bar 100mm x 10mm thick and width matching the two main plates thickness. 4 pieces of aluminium square bar 10mm x 10mm @ 300mm long 4 pieces of aluminium square bar 10mm x 10mm @ 10mm long (Small spacer cubes.) 4 M8 Wing nuts 4 M8 x 40mm grub screws or same lengths of threaded rod 4 Steel washers to match 4 Nylon washers to match 6 M8 x 30mm button head cap screws. These materials are often very cheap and can often be found if you shop around at metal fabricators in industrial areas. Salvage yards are also good places to look. Note* I have used these dimensions as an example only. If you have a heavier and larger telescope then you would have to increase these sizes (including fasteners) as appropriate. Step 1. Measure, mark and cut aluminium square plates to match the size of your telescope base.
Step 2. Drill holes in square plates to match the holes under your telescope base and the top of your pier. Make sure that if the telescope base has threaded holes, then drill plate to one millimeter larger to allow the bolts to slide through later. Step 3. Drill three 7mm holes in two opposite sides of the tripod plate. Tap holes to M8. See figure 1 for example. Step 4. Drill two 7mm holes in two opposite sides of the telescope plate. Tap holes to M8. See figure 2 for example. Step 5. Drill three 8.5mm holes in the two 100mm flat bars. See figure 3 for example. Step 6. Place two 10mm x 10mm square bars beside each other with the two 10mm x 10mm x 10mm spacer cubes in between at either end. Weld these in place then file smooth. See figure 4 for example. Step 7. Assemble components as per the example in the assembled view in figure 5. Step 8. Prime and paint or anodize. Installing:
Mount the wedge on top of the pier first. Tighten all bolts. Lower top plate to level. Raise it just enough so that you can get your bolts in underneath and do them up to your telescope base. Then raise your level to your latitude and do up the wing nuts.
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