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Hi,
Geoff is correct.
The mounting hardware for the altitude encoder is easily fabricated from a piece of aluminium or thin stainless steel sheet or strip using normal workshop power tools.
The Azimuth Encoder is not so easy. You need to centrebore a bolt of approximately 1/2" diameter (see below) on a lathe and then drill and tap through the side of the bolt head with about an M3 or 1/8 grub screw. You attach the encoder shaft through this centrebore, locked in place with the grubscrew and the encoder itself is mounted on a bracket thats not so hard to fabricate from s/steel or aluminium similar to the altitude encoder. The next slightly tricky part is that you need to use a special locking nut on the bottom of the baseboard which locks onto the thread of the bolt as its tightened so that it locks and does not undo as the base is rotated. This nut then needs to be attached to a metal plate which is fixed to the bottom of the baseboard. The last part doesn't sound difficult but it is unless you have the right equipment and know how. You could use a nylon locking nut but the difficulty here is attaching it to the base plate, any form of welding will invariably melt the nylon insert. My lock nut is a specially tapered locking thread with the nut then welded to the metal plate.
Unfortunately its not a DIY job unless you have the right tools and know how. Where are you located ? I am NSW Central Coast and would be happy to let you look at how mine are done. Next time I pull it apart I will also take some digicam shots of the azimuth mounting components.
NB: The standard supplied centrebolt on the 10" GS Dobs is 8mm which runs through a plastic sleeve. Some people when mounting the azimuth encoder use an 8mm bolt and centrebore this and retain the plastic sleeve, while others including myself use either a 1/2" Whitworth or 1/2" UNC Centrebolt and discard the plastic sleeve. Note that 1/2" Whitworth and 1/2" UNC are not interchangeable. They are, in all other sizes except 1/2", if using a 1/2" bolt you "MUST" use the matching nut. Normally Whitworth and UNC use the same Turns Per Inch (TPI) with a slightly different pitch angle so for normal use are interchangeable but in 1/2" the TPI are also different.
CS-John B
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