Pay Attention to Those Declination Top Plate Locking Knobs


M Hambrick
 

Here's a little lesson learned tidbit that I just discovered on my 1100 mount:

I have been noticing lately when setting up the mount with my 180 EDT that there is some play in the dec. axis. I thought that maybe the clutches were not tight enough, but when I checked them they were all tight. Today I was setting up the mount inside the house to do some rebalancing, and when I was attaching the declination axis I noticed a significant movement when I was holding the axis by the mounting plate. When I looked closer it turns out that it was actually the declination top plate that was moving, and when I checked the locking knobs they were loose.

I never touch these knobs, but over the months they must have worked their way loose. So the lesson I took away from this is to check those locking knobs every time I set up the mount.

Check those hand-drawn declination setting circles out in the photo. It sure would be nice to have something more permanent (hint - hint). I made these with a pencil. 

Mike


George
 

Mike,

 

Remember that there are also Safety Screws for each axis.

 

Regards,

 

George

 

George Whitney

Astro-Physics, Inc.

Phone:  815-222-6538 (direct line)

Phone:  815-282-1513 (office)

Email:  george@...

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of M Hambrick
Sent: Tuesday, February 23, 2021 10:59 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] Pay Attention to Those Declination Top Plate Locking Knobs

 

Here's a little lesson learned tidbit that I just discovered on my 1100 mount:

I have been noticing lately when setting up the mount with my 180 EDT that there is some play in the dec. axis. I thought that maybe the clutches were not tight enough, but when I checked them they were all tight. Today I was setting up the mount inside the house to do some rebalancing, and when I was attaching the declination axis I noticed a significant movement when I was holding the axis by the mounting plate. When I looked closer it turns out that it was actually the declination top plate that was moving, and when I checked the locking knobs they were loose.

I never touch these knobs, but over the months they must have worked their way loose. So the lesson I took away from this is to check those locking knobs every time I set up the mount.

Check those hand-drawn declination setting circles out in the photo. It sure would be nice to have something more permanent (hint - hint). I made these with a pencil. 

Mike


Joe Zeglinski
 

Hi Mike,
 
   Nice job on your pencilled setting circles.  I was thinking the same thing about perhaps AP providing “stick-on-tape” setting circles as visual aids for their mounts, as an option. That would save production work and materials & stocking for the old fashioned types. However, I suppose the pencil (or inked) marked ones can easily wash off or smudge, after all that hard work.
 
    Easy to make permanent ones – just measure and test print such setting angle strips  first, on paper. Later , when they seem to be correct with their ends taped/joined, plastic ones could then be printed with a laser printer,  onto “overhead projection cell” material, as a clear acetate glue-on. You might have to print on the sheet’s diagonal, depending on axle cap diameter, to fit – or even as two pieces, 180 degree strips. I would first “reverse” the printing image, so that once it is printed (mirror imaged) and flipped over, the lettering would be on the back side of the strip, protected from dew etc.
 
    Might even glue the printed strips onto “Glow in the dark”  tape, before applying that tape to the axle. That way, it will be easier to read the angles with the glow backlighting effect,  even without a permanent battery operated LED indicator bulb. But don’t forget to account for the tape’s thickness, adding to the diameter, when measuring the printed setting circle  strips.
 
Joe Z.


Shailesh Trivedi
 

Mike,

Are you referring to the silver knobs under the DEC plate? If they come lose do you not have holding screws? 

On a side note: do you have any tracking or balancing issues with the 180EDT? Is it on a permanent pier or a tripod? 

I have a TEC180 and am wondering about a moment-arm for my AP1100. 

Shailesh


M Hambrick
 

George & Shailesh

Good point about the holding screws. For some reason I seem to recall reading in the mount assembly instructions that they did not need to be installed if the user was planning to remove the declination top plate. Anyway, for whatever reason I never installed them. It was not long after I got the mount that I got a DOVELM162 which eliminated the need to ever remove the declination top plate. As soon as I finish this post I am going to install them.

As for the 180 EDT on the 1100 GTO mount, I have had no issues with balancing. As far as loads go, I have the scope with a pretty large and heavy SBIG STXL16200 camera and filter wheel. For guiding I use a Tele-Vue Pronto with a SBIG ST2000-XM camera piggybacked on top of the 180 EDT rings. I also have a ST-i guiding camera, but I really like the wide field of view with the ST2000. It is much easier to find guide stars. For balancing you can see my counterweight arrangement in the attached sketch. If I had a couple more 18 lb counterweights I would move more of the weight up to the top of the counterweight shaft to minimize the moment arm.

My guiding is decent enough, but I think I could do better. With an image scale of 1.1 arc-seconds per pixel, the 180 EDT really shows poor guiding. Roland has stated on many occasions that it is a bad idea to use a piggyback guide scope due to flexure. I use an A-P portable pier, and I set up and take the mount down every night, I only use the RAPAS for polar alignment, but this seems to be pretty accurate. I have not updated the PEC since I bought the mount. 

I use MaxIm DL for guiding, running separate sessions for imaging and guiding. Lately I have been working on my guiding parameters (guide exposure time, exposure delay, etc) to see if I can get better guiding, and based on Roland's comments in another post, I am going to try multi-star guiding as well. I may try to invest in one of the A-P guide scopes that mounts directly on the main OTA to eliminate the piggyback guiding, but the 250 mm focal length of the A-P guide scope seems rather short for the 180.

Mike



M Hambrick
 

Hi Joe

Great suggestions about using tape to mark out setting circles. I may give that a try. I used pencil to make the marks because I wanted to be able to remove them if necessary. The pencil smudges very easily however.

Mike


Shailesh Trivedi
 

I use an A-P portable pier, and I set up and take the mount down every night, I only use the RAPAS for polar alignment,

Mike I am impressed that you can take the scope down every night and use RAPAS as the only polar alignment method. I have a TEC 180 currently on a Paramount MX and am contemplating using my AP1100 with AE. I too have a portable setup but with the Losmandy HD tripod.  I have tried 3x 20lb counter-weights (or could be 18lb, I forget), and one 10lb cw for balancing indoors,  to try the TEC on my AP1100 with a FLI 16803 + FW and MMOAG, My current AP1100 setup is a modest Tak FSQ106 with a Moravian G4 but I am still at the starting phase with getting it polar aligned using Pempro since I do not have visibility of Polaris even though I have the RAPAS.

Shailesh


Jeffc
 

With the 1100, if one can handle the heft, the mount can be left in the "assembled" state (sans Dec plate and saddle) which reduces the setup/teardown time a bit (and simplifies the issue due to the through-mount cables).
Note the removable Dec place comes in real handy in this situation.
I also use the 1100 in a "portable" fashion... on a Losmandy HD (old style) tripod.   The Losmandy HD Tripod adapter remains on the mount for transport, and assembly just requires inserting the three large knurled bolts.    There are other details of course like installing the Control Box.    But I will warn... lifting the whole mount is a "heft".. i think it weighs about 40lbs... which to me seems about the same as the 1200 RA axis.   (I'm not sure I would recommend this tripod... it is definitely more than good enough for visual... with imaging the verdict is still out for me... I had some guiding issues but it might be operator error.)

Lick-Public-Program.jpeg


On Tue, Feb 23, 2021 at 9:44 PM Shailesh Trivedi <strivedi@...> wrote:
I use an A-P portable pier, and I set up and take the mount down every night, I only use the RAPAS for polar alignment,

Mike I am impressed that you can take the scope down every night and use RAPAS as the only polar alignment method. I have a TEC 180 currently on a Paramount MX and am contemplating using my AP1100 with AE. I too have a portable setup but with the Losmandy HD tripod.  I have tried 3x 20lb counter-weights (or could be 18lb, I forget), and one 10lb cw for balancing indoors,  to try the TEC on my AP1100 with a FLI 16803 + FW and MMOAG, My current AP1100 setup is a modest Tak FSQ106 with a Moravian G4 but I am still at the starting phase with getting it polar aligned using Pempro since I do not have visibility of Polaris even though I have the RAPAS.

Shailesh


Roland Christen
 

Off-axis guider is preferred method for guiding a long refractor. Next best would be to mount a Baader Guide scope using our special bracket right on the tube itself. Worst method is to mount a guide scope on top of the rings.

Rolando



-----Original Message-----
From: M Hambrick <mhambrick563@...>
To: main@ap-gto.groups.io
Sent: Tue, Feb 23, 2021 10:09 pm
Subject: Re: [ap-gto] Pay Attention to Those Declination Top Plate Locking Knobs

George & Shailesh

Good point about the holding screws. For some reason I seem to recall reading in the mount assembly instructions that they did not need to be installed if the user was planning to remove the declination top plate. Anyway, for whatever reason I never installed them. It was not long after I got the mount that I got a DOVELM162 which eliminated the need to ever remove the declination top plate. As soon as I finish this post I am going to install them.

As for the 180 EDT on the 1100 GTO mount, I have had no issues with balancing. As far as loads go, I have the scope with a pretty large and heavy SBIG STXL16200 camera and filter wheel. For guiding I use a Tele-Vue Pronto with a SBIG ST2000-XM camera piggybacked on top of the 180 EDT rings. I also have a ST-i guiding camera, but I really like the wide field of view with the ST2000. It is much easier to find guide stars. For balancing you can see my counterweight arrangement in the attached sketch. If I had a couple more 18 lb counterweights I would move more of the weight up to the top of the counterweight shaft to minimize the moment arm.

My guiding is decent enough, but I think I could do better. With an image scale of 1.1 arc-seconds per pixel, the 180 EDT really shows poor guiding. Roland has stated on many occasions that it is a bad idea to use a piggyback guide scope due to flexure. I use an A-P portable pier, and I set up and take the mount down every night, I only use the RAPAS for polar alignment, but this seems to be pretty accurate. I have not updated the PEC since I bought the mount. 

I use MaxIm DL for guiding, running separate sessions for imaging and guiding. Lately I have been working on my guiding parameters (guide exposure time, exposure delay, etc) to see if I can get better guiding, and based on Roland's comments in another post, I am going to try multi-star guiding as well. I may try to invest in one of the A-P guide scopes that mounts directly on the main OTA to eliminate the piggyback guiding, but the 250 mm focal length of the A-P guide scope seems rather short for the 180.

Mike



--
Roland Christen
Astro-Physics


M Hambrick
 

Thanks for the photos Jeff C.

In my younger days I used to carry my assembled 800 mount and 8-inch portable pier all at once, but no more. Everyone is talking about climate change, but what we should be talking about is gravitational constant change. What used to feel like it weighed 50 pounds when I was 38 now feels like it weighs over 100 pounds :>)

Shailesh - When I saw the photos from Jeff C they reminded me of a balancing issue that I had with my 180 EDT when I first got the mount. In Jeff's photo, the refractor in the rear with a 900 ? or 1200 ? mount on the 8-inch Astro-Physics portable pier looks very similar to what I started out with when I got my 1100 mount. You will also notice that his scope is attached to the mount on one of the A-P 18-inch Flat Plates (FP1800). I originally ordered my 1100 mount with one of these flat plates. I had to modify the plate by drilling some holes in it to match the hole pattern on my old 1992 vintage 8-inch rings, but when I was setting up everything inside the house to do the initial balancing, I could not get the scope to balance on the declination axis in the imaging mode with the camera attached. It was very heavy to the rear.

Rather than trying to drill additional holes in the flat plate, I solved the problem by purchasing one of the 16-inch dovetail saddle plates (DOVELM162) along with the 16-inch dovetail plate (SBD16). When I attached the scope to the mount using the DOVELM162 and SBD16 I was easily able to achieve balance in the declination axis by sliding the dovetail plate forward in the saddle plate.

The DOVELM162 and SBD16 have been one of the best investments I have made since purchasing the 1100 mount, and if you don't have them I highly recommend getting a set. I also purchased a couple of SBD12 dovetail plates to use with my smaller imaging scopes. The big advantage to this is that I can leave the DOVELM162 attached to the declination axis, and just attach whatever imaging scope I am using. Note that when I am setting up the 180 EDT, I first attach the SBD16 and attached rings without the 180 EDT to the dovetail saddle plate with the mount in the Park 2 position. Then, once the counterweights are attached I mount the 180 EDT into the rings. I have a set of portable stairs to facilitate this.

There is one other issue I should also mention if you have one of the A-P portable piers. I purchased my pier in 1992 for my 800 mount. It had three holes in the top for attaching the mount. The 1100 mount has 6 holes in the base. Although they told me that it was not necessary to do so, I drilled three additional holes in my pier to allow me to use all six screws. The 1100 mount base fits rather loosely into the 8-inch pier, and when the scopes, cameras, etc. as described in my earlier thread are attached to the mount, it places the center of gravity well outside (to the north) of the pier, and all that weight wants to tilt the mount towards the north. Even when the bolts attaching the mount base to the pier were tight I had several occasions where the mount tilted by about 1/16 inch after everything was attached and polar aligned using the RAPAS. To minimize the chance of this from happening I purchased some split Nord-Lock lock washers from McMaster-Carr (see below). These have been very effective at eliminating the tilting of the mount in the pier.

Mike


 

On Tue, Feb 23, 2021 at 02:40 PM, Joe Zeglinski wrote:
Hi Mike,
 
   Nice job on your pencilled setting circles.  I was thinking the same thing about perhaps AP providing “stick-on-tape” setting circles as visual aids for their mounts, as an option. That would save production work and materials & stocking for the old fashioned types. However, I suppose the pencil (or inked) marked ones can easily wash off or smudge, after all that hard work.
 
    Easy to make permanent ones – just measure and test print such setting angle strips  first, on paper. Later , when they seem to be correct with their ends taped/joined, plastic ones could then be printed with a laser printer,  onto “overhead projection cell” material, as a clear acetate glue-on. You might have to print on the sheet’s diagonal, depending on axle cap diameter, to fit – or even as two pieces, 180 degree strips. I would first “reverse” the printing image, so that once it is printed (mirror imaged) and flipped over, the lettering would be on the back side of the strip, protected from dew etc.
 
    Might even glue the printed strips onto “Glow in the dark”  tape, before applying that tape to the axle. That way, it will be easier to read the angles with the glow backlighting effect,  even without a permanent battery operated LED indicator bulb. But don’t forget to account for the tape’s thickness, adding to the diameter, when measuring the printed setting circle  strips.
 
Joe Z.
 
 
I used that exact technique to make various labels and scales for equipment I made or used at work. Thought I was the only one. :)  Solve the various angles and lengths of the label with a CAD program and many tests, since most printers aren't as accurate as I expected.  Mirror them in the program, laser print on overhead projector acetate sheets (wonder if they're still around), cut out, flip and attach using double-sided tape with the toner safely underneath.  Worked great.

Jerome