Hi Baharath

Happy New Year

I found this on the A-P web site in the description for the 10-inch portable piers:



Note that I can't find the M12012-C adapter plate on the A-P web site, but I am pretty sure it exists.

On the same topic I thought I would pass on some additional recommendations based on my experience with an 8-inch pier and 1100GTO mount. Note that my pier is quite a lot older. I bought it in 1992 before there were any GOTO mounts or CCD cameras. I think that A-P manufactures their piers to tighter tolerances these days, but it is still worth knowing what to look for in order to avoid potential problems later.

Once you get the necessary parts you will want to check the fit of the flat surface adapter on the top of the 10-inch pier to make sure that there is no wobble. In your case you will use the M12012-C to find the high spots. The photos below show the process that I used to do this. It is very important that the adapters and mount sit squarely on the top of the pier with no wobble or play. Otherwise, your polar alignment can shift if the mount moves after everything is attached.

Step 1: Coat the top surface of the pier with layout dye.


Step 2: Use the adapter plate to find the high spots on the top of the pier by placing it on the pier and rotating it back and forth to rub the dye off at the high spots. Note that if you see three or more high spots, or if the adapter is making good contact all the way around the pier you do not need to do any more. In the photo below you see two points of contact. This resulted in a significant wobble when the mount was placed on the pier.


Step 3: Use a file to gently scrape the high spots. It is important to work slowly because the file will quickly cut the aluminum. After scraping each high spot, retest the fit with the adapter. Repeat the process until the adapter is making contact at multiple points. Each time you scrape the top of the pier with the file, the contact points will either ger wider, or else you will find a new contact point. When scraping the high spots, you have to be sure to scrape each one. 


Once you have a flat surface on the top of the pier, the next thing you will need to do is to use high performance lock washers when you attach the adapter to the pier. The mounting holes in the pier are slightly oversized, and they will allow the whole mount and mounting plate assembly to tilt in the pier once all of the counterweights and scopes are attached. This is because the center of mass is not over the center of the pier, but instead, over the north edge. This will have a tendency to pull the south side of the mount up if there is too much clearance in the mounting holes. Using high-performance lock washers to attach the adapter plate to the pier can eliminate this possibility. I recommend using stainless steel NORD-LOCK two-piece wedge lock washers. These are available from McMaster-Carr.



Mike