Optical Encoder Mounting on GS Dob - Help!

[netwolf]

I have Celestron Advanced Astro Master with 2x 2048 Optical Encoders. I need some help and ideas in mounting these using standard bolts and bits you can pickup from bunnings. I know few of you have installed OE's on your DOB's and if you could point me in the right direction it would be much appreciated. I have looked at the machined solution provided by Argo Navis makers, but these are expensive and i am on a budget. At preset I have a GS-880, it has roller bearing on a thin sheet for az and the standard Alt.

I need suggestions, pictures or drawings if possible of your ideas for AZ and Alt replacements that would allow the addition of the encoders.

Idealy I would like a bolt with a head that has hole in it for the encoder, and a setscrew on the side that can be tightined to hold the encoder shaft in place. For Az then i could use a Tee nut on the other end to hold it in place to the ground board. For Alt it would just replace the current bolt and screw into the same hole.

Any help would be appreciated.

Thanks and Reagrds
Netwolf

[Starkler]

I doubt you will find the bits at Bunnings.
The only cheap way I can fathom is if you have a mate with access to a lathe to turn something up for you. Without accuracy in construction ie the encoder shaft exactly concentric with the scopes axis its next to useless.

[netwolf]

The kit i have has some bits for the encoder to attach to celestron scopes. One pieces could neetly fit over the Pivot bolt, but needs threading on the inside which my mate can do. However i still need to find a way to lock that bolt to the ground base.. I could put a Tee nut in the between the two boards facing down. That would lock the base in place. Then i get some nylon bussing to replace the aluminium one i replaced, cut this in two one for the portin between the bolt head and the Tee nut on the groun board and the other between the remaining bolt lenth up through the rocker base. Replace locknut with the afore mentioned kit piece. The piece is a hollow T bolt with bolt head drilled for the encoder shaft.

What do ya think will it work.. It should be centred as the T Bolt fits over the Bolt. I am wondering if i need to even increase the bolt size if i use nylon bushing it could be tight.

Regards
Netwolf.
PS: i can not belive i said all that ... as they say necessity is the mother of all things.

[ausastronomer]

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

[netwolf]

I spoke with Garry at Wildcard Innovations, a nice long chat with lots of good information. He was in no way pushing his product and gave a good overview of the market place for machined mounts. For a $100 i think i am best buying it from him.

Also it means i can later upgrade my encoders to the higher resolution if need be and eventually get the Argo Navis, the best DSC arguably in the world. And its made in Australia. Wish more was made here a lot more.

Ausastronamer i am in sydney, your post forced me to rethink and call Garry. Thanks.

Regards
Netwolf

[ausastronomer]

Netwolf,

There is no one more knowledgeable in this area than Gary, likewise he is one of natures' gentleman. You've spent your $100 very wisely.

CS-John B

[netwolf]

Intially i was in a rush to get my setup up this weekend but i think ill be better of doing it right rather than rush into it. Ill place the order on Monday and hopefully i will be right to go by next weekend. Now if i can only find some one to make me a EQ platform...

Regards
Netwolf

[netwolf]

I got my mountings today, but dont have a drill so i thinkt its about time i get one. Thanks Gary your a star. Gary even called me to check i had the right cables and all, now thats customer service.

Regards

[elusiver]

netwolf.. if you don't mind me asking.. how much did u pay for the DSC??

el :)

[netwolf]

Hi Elusiver,

It was a mates price bargain.. $280 with 2x encoders (2048's). Recently found out it does not have a RS232 chip in it but the PCB has a spot for it.

[netwolf]

Intresting build your own DSC.
http://home.earthlink.net/~david.ek/digicircles/dsc.html

[elusiver]

yeah seen that netwolf... been thinking about the palm dsc.. might be a project to work on after the focuser.. and the eq platform...


el :)

[netwolf]

My order of priority is
1. DSC
2. Tracking Alt-Az short term for Planetary imaging.
3. Webcam imaging or WATEC 120N CCTV camera for imaging and visual.
4. EQ Tracking.
5. upgrade DSC to Argo Navis.

[elusiver]

netwolf.. it sounds very very familiar. My priorities.

1. Motorised Focuser(which i don't think i really really want now.. but I've gotto finish it off)
2. Palm DSC
3. Tracking Platform.
4. Argo Navis(everyone want's the AN!)

el :)

[netwolf]

my 2 and 4 keep fliping decisions decisions... AltAz tracking vs EQ platform...