Help with ADA2003A


weems@...
 

I just bought an ADA2003A for my 2.7" focuser, and it appears to be a bit larger in diameter than the original tailpiece. This is for a 1985 AP 6"f9. The original tailpiece is quite loose in the focuser, and only stabilizes when tight against the stop. The ADA2003A will screw in about one full turn. So it's actually close. (Picture attached)  Has anyone dealt with this issue previously? I don't want to try anything that would make it non-returnable, like sanding down the threads, unless it's known to work.

I'd really like to be able to use it. With a heavy eyepiece in a diagonal, if I've tightened down the thumbscrew hard, the tailpiece will start to unscrew. With one thumbscrew, if I don't tighten it hard, then the diagonal pivots. The screw marks the barrel of the diagonal. And the 2" opening of the tailpiece is a little oversized, so the image can shift by up to about 1' of deflection. I've lived with this for issue for 36 years, but generally just used light eyepieces with the original 706 mount. Recently, however, I've started using a 41mm Panoptic, and I've also moved to an AP900 that I'm trying to finely tweak for pointing accuracy. So I'm trying both to remedy the flopping, and also to be able to take out orthogonality error. With the crosshair able to shift by up to a minute, it's hard to know if I've really zeroed out the error. 

Chip Weems

 


Roland Christen
 

The focuser of that vintage scope has slightly different dimensions, so you would need to send your focuser in so we can adapt to that thread, or replace the barrel for a newer one.

Roland



-----Original Message-----
From: weems@...
To: main@ap-ug.groups.io
Sent: Fri, Jan 15, 2021 10:11 pm
Subject: [ap-ug] Help with ADA2003A

I just bought an ADA2003A for my 2.7" focuser, and it appears to be a bit larger in diameter than the original tailpiece. This is for a 1985 AP 6"f9. The original tailpiece is quite loose in the focuser, and only stabilizes when tight against the stop. The ADA2003A will screw in about one full turn. So it's actually close. (Picture attached)  Has anyone dealt with this issue previously? I don't want to try anything that would make it non-returnable, like sanding down the threads, unless it's known to work.

I'd really like to be able to use it. With a heavy eyepiece in a diagonal, if I've tightened down the thumbscrew hard, the tailpiece will start to unscrew. With one thumbscrew, if I don't tighten it hard, then the diagonal pivots. The screw marks the barrel of the diagonal. And the 2" opening of the tailpiece is a little oversized, so the image can shift by up to about 1' of deflection. I've lived with this for issue for 36 years, but generally just used light eyepieces with the original 706 mount. Recently, however, I've started using a 41mm Panoptic, and I've also moved to an AP900 that I'm trying to finely tweak for pointing accuracy. So I'm trying both to remedy the flopping, and also to be able to take out orthogonality error. With the crosshair able to shift by up to a minute, it's hard to know if I've really zeroed out the error. 

Chip Weems

 


weems@...
 

Thanks for your reply, Roland. I also have the original 2.7" camera adapter that fits snugly inside the focuser tube. I don't use it that often, since I'm 99% visual, but it would be nice to keep it as an option. 



So which approach would you recommend? Adapting the thread or replacing the barrel? If a replacement barrel would be larger, I suppose the adapter could be shimmed. And I assume I should just use the contact form to get details about sending it in? 

Chip


Roland Christen
 

If you ship us the parts we can figure out the best way to fit everything together.

Roland



-----Original Message-----
From: weems@...
To: main@ap-ug.groups.io
Sent: Sat, Jan 16, 2021 11:40 am
Subject: Re: [ap-ug] Help with ADA2003A

Thanks for your reply, Roland. I also have the original 2.7" camera adapter that fits snugly inside the focuser tube. I don't use it that often, since I'm 99% visual, but it would be nice to keep it as an option. 



So which approach would you recommend? Adapting the thread or replacing the barrel? If a replacement barrel would be larger, I suppose the adapter could be shimmed. And I assume I should just use the contact form to get details about sending it in? 

Chip


Karen Christen
 

Chip, if you choose to send your components in please call our office and speak with Daleen or Paige.  They will help to facilitate the process. 

Karen

AP

815.282.1513

 

From: main@ap-ug.groups.io <main@ap-ug.groups.io> On Behalf Of Roland Christen via groups.io
Sent: Saturday, January 16, 2021 12:18 PM
To: main@ap-ug.groups.io
Subject: Re: [ap-ug] Help with ADA2003A

 

If you ship us the parts we can figure out the best way to fit everything together.

 

Roland

 

 

 

-----Original Message-----
From: weems@...
To: main@ap-ug.groups.io
Sent: Sat, Jan 16, 2021 11:40 am
Subject: Re: [ap-ug] Help with ADA2003A

Thanks for your reply, Roland. I also have the original 2.7" camera adapter that fits snugly inside the focuser tube. I don't use it that often, since I'm 99% visual, but it would be nice to keep it as an option. 



So which approach would you recommend? Adapting the thread or replacing the barrel? If a replacement barrel would be larger, I suppose the adapter could be shimmed. And I assume I should just use the contact form to get details about sending it in? 

Chip


weems@...
 

Thank you. It may be a little while before I call, as I would like to finish fine tuning my drift alignment and then seeing if I can identify other sources of pointing error before I have to pull the scope out of the observatory and reconfigure for another one, while the focuser is being serviced. Hopefully we'll get some clearing over the next week or so, and I'll be able to wrap it up soon.

I have the azimuth adjusted for no drift in 30 minutes, but altitude is still showing some after 10 minutes. Pointing errors are still up to 10 arcminutes for a worst case slew from near one side of the meridian to near the other side (e.g., going from Mintaka to Alnitak when Alnilam is on the meridian). The mount is working pretty much flawlessly, returning back to the starting point of that slew with less than a minute of difference. So it has to be in my alignment, orthogonality, or in flexure. Orthogonality could be off by a minute or two - it seems to vary about a minute, depending on orientation, which could indicate some flexure.  But with the current tailpiece being a bit loose, it's possible that the reticle isn't collimated, or is moving. If I can eliminate the remaining polar alignment error, it will give me a better sense of what's left to work on, and what remains to be gained by doing so.

The accuracy of the mount is inspiring me to work toward making the most of it. My interest is in looking visually for fainter objects, so I'd like to get the pointing as close as possible. 

Chip


weems@...
 

Weather and work have delayed my getting back to work on the alignment. With the arrival of a recently ordered Maxbright diagonal and a couple of decent nights, I did discover that my trusty old Lumicon diagonal was suffering from a significant mis-collimation, so I'll need to re-do my orthogonality corrections (still fighting the looseness of the 2" tailpiece).

I've been wondering, too, about replacing the entire focuser. It's a bit concerning to me that the online notes indicate a need to shorten the OTA by an inch, which I certainly don't have the tools do do properly. I know that Starlight Instruments has done an adapter for the 6"f8 and one of their 3" focusers, with no mention of shortening the tube. So I wonder how necessary it is? Currently my eyepieces are par focal with about 3" of extension of the focuser tube.

But the other concern is the camera adapter/field flattener previously pictured, which has a diameter of 2.69" at the flange and no threads. That wouldn't fit a new 2.7" focuser. Its barrel is 2.5" in diameter, so I don't know if it is possible to make an adapter for a 2.7" focuser that would mushroom out to fit around the flange. 

Chip


weems@...
 

After some back and forth email with George, it was becoming clear that even if I returned the focuser, it would be iffy as to whether anything could be done for it. So I went ahead and took the tips of the threads on the ADA2003A down by a tiny bit with a micro-file, then chased them with a narrow needle file. I chucked it in my wood vice, and turned the focuser tube in and out on it, using a little machine oil, until it was possible to run it all the way in by hand. Then I cleaned everything thoroughly. Basically, it amounted to removing the anodizing layer from the threads. 

Of course, this got me started down the path of re-doing the baffling on the OTA, so it will be a while before I put it back into service. But at least I now know that I can get the diagonal to stop flopping around, and I can keep the reticle eyepiece centered while trying to shim out the orthogonality.

Chip


ROBERT WYNNE
 

Wonder how thick is the anodizing layer; .001" - .003" thick? -Best, Robert

On 04/28/2021 7:30 PM weems@... wrote:
 
 
After some back and forth email with George, it was becoming clear that even if I returned the focuser, it would be iffy as to whether anything could be done for it. So I went ahead and took the tips of the threads on the ADA2003A down by a tiny bit with a micro-file, then chased them with a narrow needle file. I chucked it in my wood vice, and turned the focuser tube in and out on it, using a little machine oil, until it was possible to run it all the way in by hand. Then I cleaned everything thoroughly. Basically, it amounted to removing the anodizing layer from the threads. 

Of course, this got me started down the path of re-doing the baffling on the OTA, so it will be a while before I put it back into service. But at least I now know that I can get the diagonal to stop flopping around, and I can keep the reticle eyepiece centered while trying to shim out the orthogonality.

Chip