Astro-Physics strongly recommends the use of a flat top-plate and their 3600 Flat Surface Adapter when designing your setup for the 3600GTO mount, regardless of whether you are using a portable or a permanent pier. Bolt this adapter onto the flat plate at the top of your pier.
The AP 3600GTO Mount fits into the ID of the adapter; eight side bolts hold the mount in place. This adapter is machined from a solid plate and is ribbed in the base for strength and reduced weight. It is 12" OD, 1 7/8" tall and weighs 5.75 lb.
The Bolt Circle of the 3600FSA:
- Eight (8) holes for 3/8" bolts on a 10.788" diameter bolt circle
- Three (3) holes for 5/16" bolts spaced 4.25" from the center and one (1) hole, also for a 5/16" bolt 3.125" from the center. This spacing allows you to attach the adapter to the 1200 Standard Pier Adapter (1200SPA), which allows it to be used with a 10" diameter pier. Please note that this is not a recommended practice for a permanent setup or for a very large instrument, however.
- Center hole for a 5/16" bolt to use if you choose.
Check out the dimensional drawing for the 3600FSA Flat Surface Adapter.