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ADM vs Losmandy

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#26 TheMenace

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Posted 09 March 2009 - 12:28 PM

The dove tail is used to mount the ota on my atlas.
The vixen style just uses one screw on each end to mount the dove tail to the ota,rather than the blocks shown in the photo above..
You'll need the vixen version.

http://admaccessorie...roducts/VC8.htm

#27 Ido Graiman

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Posted 09 March 2009 - 01:33 PM

But then my OTA will be held by two screws! (one on each side of the OTA). It doesn't seems to be safe...

Isn't there a way to attache the vixen-style dovetail (I have both the 8" and the 13" one - from Orion) to the Losmandy dovetail?
Also - doesn't the Atlas comes with vixen-style head?

#28 mclewis1

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Posted 09 March 2009 - 02:23 PM

Yes the Atlas uses a Vixen compatible saddle. The similar to the Atlas new CGEM and NEQ-6 mounts apparently use Losmandy D compatible saddles.

Vixen compatible dovetail rails are 1.75" in width. Losmandy D type plates are ~4" wide (the actual dovetail is 3" wide at its narrowest point). Careful with the nomenclature as Losmandy also makes a V or Vixen compatible rail as well.

Either the Vixen dovetail rail or the Losmandy D type plates should IMHO be on some form of "base". This can take the form of small radius blocks at each end of the rail/plate or a full length plate that the dovetail rail bolts onto (see Scopestuff http://www.scopestuff.com/ss_mpc8.htm for a picture and better explanation).

The exception to the idea of using separate blocks or plates is the Celestron CGE rail ... it is a Losmandy D compatible rail that because of it's unique shape can be bolted directly to the OTA.

Ido, I'm with you ... I'd never want my scope held to the dovetail rail by only two bolts unless it was sitting on a flat surface (like that provided by the radius blocks or full length plate). When a dovetail rail is bolted down to the blocks it can make use of a much heavier bolt.

#29 Ido Graiman

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Posted 09 March 2009 - 02:51 PM

So, this brings me to the logic conclusion (at least in my mind) that a combination of both the Losmandy D dovtail and a vixen-style dovetail is probably the best solution; The Losmandy dovetail providing enough 'traction', and the vixen-style dovetail attached to the Losmandy dovetail with more then two bolts (4, in case of the dovetail provided by Orion).
The question is - is there a way to connect the two different types of dovetails, or do I need to replace my HEQ5 mount head so that it can work with Losmandy D type dovetail?

Am I the only 8" SCT owner encountering this problem?

BTW, the plate scopestuff sell doesn't solve the problem since it's flat. Therefore - again, there can be only 1 screw at either side of the OTA attaching the two. They do not provide some radius blocks...

#30 DaveJ

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Posted 09 March 2009 - 03:25 PM

Hi Ido,

Here are three photos that I believe will clear things up for you.
All three show the mounting techniques for a C-11 using Losmandy "D" plate and saddle.

Here's the first showing the "D" saddle. The "V" saddle (Vixen, CG5, etc) is similar, but much smaller and less robust...

Attached Files



#31 DaveJ

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Posted 09 March 2009 - 03:27 PM

Here's a photo showing the Losmandy "D" rail and radius blocks I use on my C-11:

Attached Files



#32 DaveJ

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Posted 09 March 2009 - 03:29 PM

and one more:

Attached Files



#33 Ido Graiman

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Posted 09 March 2009 - 03:31 PM

Thanks Dave. Still, as I previously said - it means I have to either find a way to replace the saddle on my mount to work with a D type dovetail, or I have to find a way to attach the V type dovetail to the D type dovetail (since no matter how hard I googled, I wasn't able to find any V type dovetail that comes with radius blocks).
Or am I still missing something?

Thanks :)

#34 DaveJ

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Posted 09 March 2009 - 03:36 PM

Each of the radius blocks are held to the OTA with two screws. The rail is held to each radius block with two more screws. The whole system is pretty secure and I never worry about something coming loose. This same system is available for most any OTA in either the "D" (larger) or "V" (smaller) rails/saddle. Losmandy and ADM both provide most anything you would require for any OTA, to my knowledge. My refractor has rings that attach to a Losmandy style plate so it can be placed in the saddle instead of the C-11. Also available from Losmandy & ADM are dual-saddle arrangements that allow both the C-11 and refractor to be mounted simultaneously.

#35 DaveJ

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Posted 09 March 2009 - 04:40 PM

I wasn't able to find any V type dovetail that comes with radius blocks).


Take a look at the VCB8 here. If I'm not mistaken, this is what you're looking for, but you'd have to call Losmandy and see if those radius blocks will work for an 8" Meade or if he's making radius blocks compatible with Meade and hasn't yet updated his web page. Do you know any machinists?

#36 Ido Graiman

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Posted 09 March 2009 - 05:02 PM

Thanks again Dave.
From what I know, the VCB8 exist only for Celestron, but I guess I'll have to give Losmandy a call and ask him. Otherwise, it seems that VSCT13 is the only thing for my OTA, meaning that it will be attached to the OTA by one bolt on each end. Maybe it's enough. Maybe it's not. I have to say that I can't see myself putting my trust in a single bolt ;)

So again, it's either getting some radius blocks for Meade (and I actually talked with 2 machinists today, and none of them gave wanted to produce a solution for me), or getting the D dovetail and finding a way to attach it to my mount (I am curious to see how TheMenace did it).

Thanks again :)

#37 DaveJ

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Posted 09 March 2009 - 05:12 PM

Ido, I would not hang an OTA from a mount with a dovetail plate held by a single screw at each end...I'm with you there. Could be the single screw idea is meant for a counterweight rail but that's just conjecture on my part. I believe a call to Scott at Losmandy is in order here. Good luck.

#38 TheMenace

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Posted 09 March 2009 - 05:35 PM

Adm makes a dual saddle plate that accepts both dove tails.
The 8" should work fine with one screw on each end as the ota does not weigh enough to cause any problems.
I would call ADM and see about the dual saddle.

The losmandy radius blocks caused me quite a few headaches,as they didn't match up with my ota.
I needed to buy 2 complete dove tails to get a set that match.

The losmandy radius blocks only use 1 screw on the corrector end of the ota,in their stock configuration,even for the 10" ota.

:shrug: :bigshock:

#39 Ido Graiman

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Posted 09 March 2009 - 06:39 PM

dual saddle plate! Aha! that was the missing link :)
I'll check ADM's saddle :)

The 8" OTA weighs about 12lbs (I assume), which still seems a lot for these screws. I'll feel a lot better with the radius blocks holding my OTA...

As for the frustration with the Losmandy blocks - I just had a talk with a friend who spent a LOT of time trying to figure out how to attach these blocks to the OTA along with the dovetail, so this story is quite familiar ;)

Thanks for the insight!

#40 Troys

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Posted 10 March 2009 - 07:39 PM

I just bought the ADM VM8 to attach my 8" LX10 OTA to the CG5. It only has 1 screw at each end. They give you longer screws to replace the screws that are there now. I was surprised but the cells are thicker then I thought they woud be.

It's only been a week but it is still tight and have had no problems.

If you look in either the classified section or the swap section someone is selling the one you need for $50.00.

#41 Ido Graiman

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Posted 10 March 2009 - 08:32 PM

Thanks for the input Troys.
Still, leaving the OTA on two screws, with such a small base footprint feels to me like a disaster waiting to happen...
I think I'll go with the Losmandy type dovetail and a suitable saddle (it might cost a few more $$$, but eventually, it will quite my worries).

Thanks again :)

#42 TheMenace

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Posted 10 March 2009 - 10:18 PM

The 8" should work great with a skinny light vixen dove tail.
Once you get over 10" and add the extra weight of the losmandy dove tail,I really start to question using one screw through the ota to keep the heavy scope attached securely to my mount.
My current 10" sct looks like it was already dropped a few times already.
:question: :slap:

#43 Ido Graiman

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Posted 12 March 2009 - 09:55 AM

Well, I do have the Orion 13" dovetail (vixen-style), which I'll try to adjust to fit my OTA (using two bolts). I'll see how it feels with that dovetail and worse case, if it still bugs me, I'll order the D type dovetail and saddle.

Thanks for the info guys. I really appreciate it!

Clear skies :)






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