ADM dual bar

[ampleamp]

A while ago I picked up a second hand but immaculate ADM dual bar, the idea being to run a side by side system. A few weeks ago I had the first opportunity to look at that rarest of things - the sun. I got quite a surprise when I got the sun centred on one scope and it wasn't even in the frame of the other; I swapped about and no difference - no surprise. This was using a 25x in the Ha and a 25x in the white light, so fairly wide views. Some fiddling about made not a blind bit of difference, as did re-setting the clamps on the bar.

I gave the bar to an engineering friend who has now re-set the clamps into the bar and dowled them in place. Relative to the bar, one clamp was 0.1mm out and the other 0.3mm across the length. He reckons they are exact now, both in az and alt although this remains to be seen whenever I get a chance.

There are certainly some fine tolerances in this game!

[steppenwolf]

Very fine tolerances indeed in this game. When I was using my ADM bar simply to mount a guide telescope, I wasn't too worried that the two telescopes weren't pointing at exactly the same point in the sky but now that I am experimenting with dual imaging, it has become more of an issue. I found that there was almost enough 'slack' in the tightening of the saddles to the mounting bar to get both collimated but I am now considering the purchase of a Sky-Watcher Guidescope Mount once I have determined whether or not it will hold a Megrez 72FD telescope/Atik filter wheel, OAG and CCD camera without introducing any flexure!

I hope your modification works well for you as the ADM system is excellent.

[brantuk]

You can allways mount a SW Alt/Az shoe on one side to fine tune the other scope.

http://www.firstligh...cope-mount.html

(woops - late to the party lol)

[The Sailor]

I have the same problem but I don't wish to drill so have been looking at the SW finderscope mount but as with Steppenwolf I need to know the tollenence. Have already checked around and Modern Astronomy is the cheapest.

Jim

[ampleamp]

No chance at trying this currently, but you are right Steve; the biggest variable now should be how tight I get each end of the clamp and whether this still creates an offset. I looked at the SW Guidescope Mount, but it looks like I would have to remove one of the ADM saddles to connect it to the bar, and transfer a losmandy saddle for the vixen on the SW. Neither of which is a great problem, but I also do not yet know the capacity of the SW - it could be carrying up 12-15Kgs. I also looked at the ADM site at their Max Guider systems - very nice, but eeeeek ££.

For now I will have to wait for a decent chance so see if I have them pointing in the same direction. Hopefully I won't have to mess around further, but for the cost of a few pints I couldn't really go wrong;

[dmahon]

Don't ADM make something similar themselves?

[dmahon]

http://admaccessories.com/Miscellaneous_Max_Guider.htm

Is what I was thinking of.

[Uranium235]

Will be watching this with interest as ive also been looking at the SW guidescope mounting, SnS do a version with a dovetail already mounted but there is still the question of how much weight it can handle, and is there a way of locking it.

Other options include the Baader stronghold:

http://www.teleskop-...ad--black-.html

Still not cheap, but that can handle 7kg, so if you visually compare the two - I dont think the SW will (safely) hold much more than 5. Until the question of capacity can be fully answered, I will be sticking with guidescope rings to get two scopes pointing at the same target, fingers crossed ive had no flex (yet).

PS: Done a little digging and managed to find a video review:

Looks promising, somebody should take a punt and let us know if its any good

[ampleamp]

Unfortunately, my friend's fix is inadequate . I had half an hour of sun this morning so grabbed the opportunity to check if both scopes would point in the same direction. When one scope is centred, the other at least now has the sun visible, but only 2/3 of the disk. No amount of playing with the clamps could tease the sun nearer the centre.

I suppose I will have to try some shims, consider a ring system or even the ADM Max Guider - I am not convinced the SW would take 12-15Kgs. I will have a word with Bernard and see what he thinks.

[The Sailor]

I spoke to Bernard regarding this but was left with a little nagging doubt, I will be getting the SW mount anyway and will try various pieces.

Jim

[Earl]

I have my second scope in guide rings to deal with this.

[The Sailor]

I am looking to do this with my third scope, a 6" SCT, doubt if it will happen.

Jim

[steppenwolf]

I have just taken delivery of the Sky-Watcher Guidescope Mount and am so far very impressed indeed - this is a beautifully made piece of kit but I have yet to try it on the sky because of the appalling conditions.

I have modified an ADM 7" Losmandy style dovetail bar to accommodate the SW unit by drilling and tapping two 5mm holes in the bar to allow three mounting bolts to be used as I didn't feel that using the single 1/4" x 20 bolt hole in the base of SW unit would be a fair test of its capabilities. I have to say that it feels very substantial with the Megrez 72FD telescope/Atik filter wheel, OAG and CCD camera installed.

[The Sailor]

Nice one Steve, but tell me, now that you have hands on one, any idea what weight do you think it would take?

Jim

[Uranium235]

Very nice Steve, let us know how you get on with it.

[steppenwolf]

I would guess around 4/5Kg but until I have had an opportunity to test it properly when autoguiding, it is difficult to say. It does feel good with the 3.4Kg that I have mounted on it but flexure is a tricky problem as just the tiniest amount of movement can cause issues when autoguiding.

[The Sailor]

Thanks Steve, well I will still be getting one whatever, just have to experiment .

Jim

[steppenwolf]

Very nice Steve, let us know how you get on with it.

Full review follows after the first clear night I get!

[ampleamp]

Oh, this will have my attention! Will be very interested to hear how you get on.

[AndyUK]

I too could be very interested in this. I have an ADM dual bar but hardly use it - With an MN190 + bits on one side (12kg), balancing was a bit of a problem for me, as the weight necessary for lateral balance started to max out the mount. I therefore tried piggybacking with guiderings, but hit flexure issues... and being afraid of going down the OAG route I settled for a 9x50 finderguider mounted on the top. However, I've suspected for some while that my guiding could probably be better with a longer FL, and if this works maybe I'll keep my ST102 just that little bit longer...

[JamesF]

I am now considering the purchase of a Sky-Watcher Guidescope Mount

With reference to an earlier thread, there's something screaming out to be made at home on a lathe

James

[The Sailor]

I already have something which will take the place of a SW Guidescope mount but it needs a bit of refinement, will come back with it at a later date .

Jim

[Uranium235]

Any update on the guidescope mount yet? Would be interested to hear whether its yielding round stars.

[dmahon]

If anyone wants to try the Max Guider and report back, one is on Astro buy/sell (listed alongside a WO 132 so it's not obvious from the title).

[The Sailor]

Well ordered and paid for the SW GSmount now so happy chappy . Looks like I will changing the mount layout again, again, again .

Jim