Help with dimensions of ADM guidescope system

[NightCal]

I've recently bought a a Revelation 66mm apochromatic refractor (William Optics ZS66mm clone). I want to mount it piggy-backed on my Meade LX200 Classic in my roll-off roof observatory. It will replace the finderscope and will act as a widefield refractor/finderscope/guidescope/solar observing scope (with H alpha solar filter). It needs to relatively easily demountable as I also want to use it as a widefield refractor/guidescope/solar observing scope (with H alpha solar filter) on a dual bar with my Orion 80ED mounted on an HEQ5 Pro mount.

To fulfil all these functions I have concluded that it needs to be mounted in guidescope rings on a Vixen-type dovetail bar. The ADM guidescope and V mounting bar system looks ideal. However, I have one problem, the distance between the top of the telescope and the bottom of the observatory roof as it opens is only 135mm. Can anyone help me with some questions about the dimensions of the ADM mounting system?

1 - What is the height of the ADM V system mounting bar (Vixen/Skywatcher dovetail)?
2 - What is the internal diameter of the ADM 100 mm guidescope rings?
3 - What is the external diameter of the ADM 100 mm guidescope rings?
4 - What is the length of the tipped - bolts used in the ADM 100 mm guidecscope rings?
5 - What is the specification (diameter, thread) of the tipped- screws used in your 100 mm guidescope rings?
6 - What is the internal diameter of the ADM 90 mm guidescope rings?
7 - What is the external diameter of the ADM 90 mm guidescope rings?

Thanks

[marki]

If you are going to use the ADM rings you need to buy

http://www.admaccessories.com/MDS_guidescope_kit.htm

1. the mounting rail is 15mm thick

2. 102mm

3. 112mm

4. 40mm

5. Looks like M8 x 1.25

6. Don't know

7. Dont know

The mounting rail has a v slotted into each side about 3 mm from the top. The rings have a flat machined on the bottom to which the mount clamps attach. At a guess the clamps add about 5 - 10 mm to the height when mounted on the rail. I use the ADM kit with 100mm rings to mount my ZS 66 on a meade LX200 and it works OK. You will also need a 3D balance kit to go with it.

Cheers

Mark

[NightCal]

Thanks
It looks as though the 100mm rings on top of a mini rail system is going to be too tall 15mm (rail) + 10mm (clamp) + 112mm (rings) = 137mm. I'll then have to add the height of the top adjustment bolts on to that. I only have a maximum of 135mm clearance, so it looks like the mini-rail system is out.

[Dennis]

I’m going from memory here so I may be mistaken, but I think that the x3 nylon tipped adjustment bolts on my 5 year old ADM mounting rings had a thread of 3/8” UNF. The pitch was a fine pitch and not the usual coarser UNC pitch of the 3/8” bolts I can buy in Bunnings.:shrug:

Cheers

Dennis

[marki]

Have you thought about mounting the guidescope on the bottom of the tube??? The rail can be fixed to either side of the scope, that way top clearance is not a problem. You will still need to counter balance the tube though and the standard Meade 3D system may be the go as it has a low profile, just put it on top rather then the bottom of the tube. The link below is to OPT for a 14" but they make them for all sizes and you should be able to get them in the UK.

http://www.optcorp.com/product.aspx?pid=439-735-183-879-2485

Mark

[NightCal]

Unfortunately mounting it on the bottom of the scope is a complete non-starter. I already have a restricted view to the south. Mounting this on the bottom of the scope will restrict the south views even further. There are also clearance issues when bottom-mounting a scope.

[marki]

Sounds to me like it time for a new obs or at least a major over haul of the existing one.


Mark

[NightCal]

Not a hope!! Although ...
... I suppose I could raise the whole roof a little bit (probably no more that 10mm).

The trouble is that that would be a lot of work and I'm not sure my back (or my wife) could take the strain!!!