Saddle Plate For RASA 11


Brett Hardy
 

I am looking for assistance from anyone with experience mounting a RASA 11.  I have a RASA 11 on order and will mount it on my AP 1200GTO.  I am looking at the DOVELM162 saddle plate from AP and believe it will accomplish the task, but would appreciate any input from those who have actually mounted this telescope.

Celestron has this to say: 
“The CGE and Losmandy D formats are similar, but not identical. Losmandy plates are a millimeter or so wider, while CGE plates allow more surface area contact with the dovetail clamp.”

Thanks in advance.

Brett Hardy


O'Neal, Michael
 

On the CGE plates for the RASA, I would not recommend their use on this instrument. I replaced the original CGE mounting plates with Losmandy on my recently acquired 9.25 HD scope because of an experience that brought home the inferior quality of the Celestron plates. I was visiting a friend who was mounting a new 11" HD on his G11 mount. After assembly, we moved the setup to a corner of his garage with the focusser toward the wall. Shortly after, the optical tube, mounted on the CGE plate, slid part way off the Losmandy mount, hitting the wall. If the telescope had been further away, it would have landed on the floor, destroying the telescope. After analyzing the situation, it was determined that the CGE plate was flexing and the G11 clamps could not be tightened enough to properly secure the load. I have been using Losmandy "D" plates for many years and they are on all OTA"s that ride on my AP 1100 mount.  I recommend using the top plates available from AP as they have worked just fine with the Losmandy equipment without issues.

Mike O.


Kent Kirkley
 

Following
Mike O.
So you say you replaced the CGE plates with Losmandy "D" plates.
"D" plates are of various lengths and flat.
How did you attach them to the OTA?
Did you use radius blocks?
Did you use rings mounted to the "D" plate?
Kent Kirkley



-----Original Message-----
From: O'Neal, Michael <starman43@...>
To: main@ap-gto.groups.io
Sent: Sat, Mar 26, 2022 9:20 pm
Subject: Re: [ap-gto] Saddle Plate For RASA 11

On the CGE plates for the RASA, I would not recommend their use on this instrument. I replaced the original CGE mounting plates with Losmandy on my recently acquired 9.25 HD scope because of an experience that brought home the inferior quality of the Celestron plates. I was visiting a friend who was mounting a new 11" HD on his G11 mount. After assembly, we moved the setup to a corner of his garage with the focusser toward the wall. Shortly after, the optical tube, mounted on the CGE plate, slid part way off the Losmandy mount, hitting the wall. If the telescope had been further away, it would have landed on the floor, destroying the telescope. After analyzing the situation, it was determined that the CGE plate was flexing and the G11 clamps could not be tightened enough to properly secure the load. I have been using Losmandy "D" plates for many years and they are on all OTA"s that ride on my AP 1100 mount.  I recommend using the top plates available from AP as they have worked just fine with the Losmandy equipment without issues.

Mike O.


Christopher Erickson
 

It is my diplomatic (LOL) opinion that Celestron dovetail brackets and bars are complete rubbish. For multiple reasons.

Get Astro-Physics, Losmandy or ADM dovetail brackets and bars only. AP, of course, being by far the best.

"Always take the high road. There's less traffic."

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii


On Sat, Mar 26, 2022 at 7:20 PM O'Neal, Michael <starman43@...> wrote:
On the CGE plates for the RASA, I would not recommend their use on this instrument. I replaced the original CGE mounting plates with Losmandy on my recently acquired 9.25 HD scope because of an experience that brought home the inferior quality of the Celestron plates. I was visiting a friend who was mounting a new 11" HD on his G11 mount. After assembly, we moved the setup to a corner of his garage with the focusser toward the wall. Shortly after, the optical tube, mounted on the CGE plate, slid part way off the Losmandy mount, hitting the wall. If the telescope had been further away, it would have landed on the floor, destroying the telescope. After analyzing the situation, it was determined that the CGE plate was flexing and the G11 clamps could not be tightened enough to properly secure the load. I have been using Losmandy "D" plates for many years and they are on all OTA"s that ride on my AP 1100 mount.  I recommend using the top plates available from AP as they have worked just fine with the Losmandy equipment without issues.

Mike O.


Peter Bresler
 

My 8 inch RASA is mounted in a standard ADM Losmandy D saddle on an AP1200.


Kent Kirkley
 

Although I have had no experience with current Celestron dovetail attachment devices, I tend to agree that the Losmandy "D" series devices are superior. My question was how was he attaching them to the RASA instrument.

Kent Kirkley



-----Original Message-----
From: Christopher Erickson <christopher.k.erickson@...>
To: main@ap-gto.groups.io
Sent: Sat, Mar 26, 2022 11:33 pm
Subject: Re: [ap-gto] Saddle Plate For RASA 11

It is my diplomatic (LOL) opinion that Celestron dovetail brackets and bars are complete rubbish. For multiple reasons.

Get Astro-Physics, Losmandy or ADM dovetail brackets and bars only. AP, of course, being by far the best.

"Always take the high road. There's less traffic."

-Christopher Erickson
Observatory Engineer
Summit Kinetics
Waikoloa, Hawaii


On Sat, Mar 26, 2022 at 7:20 PM O'Neal, Michael <starman43@...> wrote:
On the CGE plates for the RASA, I would not recommend their use on this instrument. I replaced the original CGE mounting plates with Losmandy on my recently acquired 9.25 HD scope because of an experience that brought home the inferior quality of the Celestron plates. I was visiting a friend who was mounting a new 11" HD on his G11 mount. After assembly, we moved the setup to a corner of his garage with the focusser toward the wall. Shortly after, the optical tube, mounted on the CGE plate, slid part way off the Losmandy mount, hitting the wall. If the telescope had been further away, it would have landed on the floor, destroying the telescope. After analyzing the situation, it was determined that the CGE plate was flexing and the G11 clamps could not be tightened enough to properly secure the load. I have been using Losmandy "D" plates for many years and they are on all OTA"s that ride on my AP 1100 mount.  I recommend using the top plates available from AP as they have worked just fine with the Losmandy equipment without issues.

Mike O.


Jeffc
 

I’ve been using the losmandy D plates with radius blocks on a Meade 12” for many years… since the first “ACF” came out (known as “RC” back then).   I have them on the top and bottom.  The top plate makes a good “handle” for lifting the OTA.
Btw, Those plates have a safety screw which I always install.  

I use this setup with the DOVELM162 on the AP1100 and Mach2.   The AP1200 is currently using a non-longer-available Robin Cassidy 8” losmandy style saddle which is excellent but too short, so the 1200 will be getting a DOVELM162 installed this week. 

The Losmandy manufactured plates I use have radius blocks. 
I didn’t see RASA 11 plates on the losmandy website; perhaps C11 plates fit.  
You probably need to call Losmandy. 

ADM does seem to have the RASA plates and radius blocks in stock. 

I’m not sure I would use rings. 
- They would be rather expensive and add additional weight.  
- I’m not 100% sure but there would be a small gap for the felt which I think would result in less rigidity than the bolted plates. 

-jeff

On Mar 26, 2022, at 2:17 PM, Brett Hardy <hardy.brett7@...> wrote:

I am looking for assistance from anyone with experience mounting a RASA 11.  I have a RASA 11 on order and will mount it on my AP 1200GTO.  I am looking at the DOVELM162 saddle plate from AP and believe it will accomplish the task, but would appreciate any input from those who have actually mounted this telescope.

Celestron has this to say: 
“The CGE and Losmandy D formats are similar, but not identical. Losmandy plates are a millimeter or so wider, while CGE plates allow more surface area contact with the dovetail clamp.”

Thanks in advance.

Brett Hardy
_._,_._,_


Fred Robinson
 


O'Neal, Michael
 

Hi Kent,
I used Losmandy radius blocks specific for the 9.25" OTA. I have them on top and bottom with no rings on the tube. The OTA mounts to the 1100 using the AP DOVELM162, which gives me enough length to move the telescope assembly back and forth for basic balance. I then use a small weight assembly that rides on the plate for fine tuning.

Mike O.


Brett Hardy
 

Thanks to everyone for thoughts and advice on dovetail plate options, much appreciated. 

I am more than a little shocked regarding the advice to replace the Celestron supplied dovetail plate and replace it with another.  A telescope of this caliber should not require third party solutions.

Shopping I will go to source a saddle plate to replace the bottom one on the RASA.

Brett Hardy


Kent Kirkley
 

Mike
I figured as much.
The previous post was concerning the RASA 11, which I assume has a different tube diameter
than your 9.25 OTA. I don't have a RASA 11 so can't measure the diameter of the tube
to see what radius blocks are available (if any).

Kent Kirkley




-----Original Message-----
From: O'Neal, Michael <starman43@...>
To: main@ap-gto.groups.io
Sent: Sun, Mar 27, 2022 12:35 pm
Subject: Re: [ap-gto] Saddle Plate For RASA 11

Hi Kent,
I used Losmandy radius blocks specific for the 9.25" OTA. I have them on top and bottom with no rings on the tube. The OTA mounts to the 1100 using the AP DOVELM162, which gives me enough length to move the telescope assembly back and forth for basic balance. I then use a small weight assembly that rides on the plate for fine tuning.

Mike O.


Kent Kirkley
 

Brett

There is a RASA FaceBook page with lots of people who use RASA instruments.
So far as I remember, no one has complained or mentioned replacing the Celestron
CGE rails. You might check it out and ask others.

Kent Kirkley



-----Original Message-----
From: Brett Hardy <hardy.brett7@...>
To: main@ap-gto.groups.io
Sent: Sun, Mar 27, 2022 12:49 pm
Subject: Re: [ap-gto] Saddle Plate For RASA 11

Thanks to everyone for thoughts and advice on dovetail plate options, much appreciated. 

I am more than a little shocked regarding the advice to replace the Celestron supplied dovetail plate and replace it with another.  A telescope of this caliber should not require third party solutions.

Shopping I will go to source a saddle plate to replace the bottom one on the RASA.

Brett Hardy


Charles Thompson
 

There is nothing wrong with the saddle plate that comes on the RASA11 or the RASA8. I have owned both for a very long time and have never had any issues. I also use the orange celestron top rail to piggyback other scopes. I've never had any issues or concerns. Yes, there's always something better you can upgrade to but you don't need to. 





Thanks,
Charles

Sent from mobile device.


-------- Original message --------
From: Brett Hardy <hardy.brett7@...>
Date: 3/27/22 12:49 PM (GMT-06:00)
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Saddle Plate For RASA 11

Thanks to everyone for thoughts and advice on dovetail plate options, much appreciated. 

I am more than a little shocked regarding the advice to replace the Celestron supplied dovetail plate and replace it with another.  A telescope of this caliber should not require third party solutions.

Shopping I will go to source a saddle plate to replace the bottom one on the RASA.

Brett Hardy


Jeffc
 



On Mar 27, 2022, at 3:45 PM, Charles Thompson via groups.io <cthomp97@...> wrote:

There is nothing wrong with the saddle plate that comes on the RASA11 or the RASA8.


I would agree , but double check the fit is secure.  As Brett noted the CGE plate did “fit” in the Losmandy saddle.  And likely if the OTA was not so heavy it would not have slipped.

Clearly these CGE plates work just fine with CGE mounts/saddles - if not there would be more reports of “slipped plate” disasters.  
  
However from just my tangential experience with astronomy gear discussions it seems the decking decision of slightly different dimensions for the CGE saddle/plates than the “Losmandy standard” is a well known issue. 

For example , Astro-Physics has a warning on the use of the “newer” Celestron CGE plate on the DOVELM162:  

image.png

I read this as:
- celestron plates delivered before 2004 might work.  Test it first.  
- celestron plates delivered after 2004 do not work.  

 I suspect the change in plate design coincides with the celestron switch from the celestron-brandedm Losmandy G11 mount to then delivering the CGE as a replacement for the G11. 

I don’t know the definitive history, but I suspect that’s moot as one thing Is for sure:  
As of 2019 Losmandy plates are NOT compatible with CGE saddles according to this Product Bulletin from 4/23/2019:  https://www.skiesunlimited.com/pdf/AVX%20Compatibility_042319.pdf

I would expect the reverse to also apply.   And given the current RASAs ship with a CGE compatible plate, I would not expect it to be safe to use with a saddle meeting the losmandy specifications.  

 There’s a crude schematic end-view picture on the net of why the celestron plate “fits” in the Losmandy style saddle but is not “compatible”.   Pic is attached  below. 

Note the “contact surface” for the clamp… it appears to me with the celestron plate (on the right side of the drawing), the contact of the clamp is a smaller “point” rather than the side “face surface” of the dovetail.   And instead of the bottom-surface of “top of the plate” sitting _on_ the saddle, the “tip” of the rails sits way down inside the bottom of saddle.  The latter is not the correct design… but will “fit”. 
However, if it was my choice… I’d rather not put my $4k 40 pound OTA on the latter.  But maybe that’s just me.  
image0.jpeg
An alternative might be to get a CGE compatible saddle for the AP mount.    Or a losmandy dovetail with a CGE saddle on it (ie an adapter.)

Ps I have experienced “slipped” dovetails.
And it is no fun in the middle of the night.   In my case it was a guide scope+camera on a D plate on top of the main OTA.   I had installed a safety screw thankfully…. That screw saved the guide camera (a big  ST-7E) , guide scope, and likely the main OTA (FSQ106n) from getting hit by the guide camera +scope.  In this case I believe the root cause was slightly loose dovetail clamps and temperature changes.  

-jeff


Jeffc
 

On Mar 27, 2022, at 7:33 PM, Jeffc via groups.io <jeffcrilly@...> wrote:

As Brett noted
Minor clarification: it was Michael (not Brett) that noted the CGE plate slippage with the losmandy saddle.


Brett Hardy
 

I have come to the same conclusion.  I would rather spend a couple hundred dollars to replace the bottom saddle plate on the RASA, a small investment to ensure compatibility.  Tomorrow I will contact AP to purchase the DOVELM162.

Thanks everyone for you considered advice and suggestions.

Brett Hardy 


Peter Bresler
 


Anant Hariharan
 

Hi Brett - I bought RASA 11 V2 in Oct and it mounts just fine on AP1100. No need to replace.

Best

Anant


Brett Hardy
 

Anant,

Thank you for your input.  It is good to know the Celestron dovetail is compatible.  

I do have an ADM dovetail on the way to me. At least this way with two D-style mating surfaces I can be certain that I will achieve the best possible interface.  

There is too much ambiguity out there on this issue, including from Celestron.  The cost of the ADM dovetail is small potatoes in the grand scheme of things.

Brett