ASTRO-PHYSICS 900RPA User manual

Precision-Adjust Rotating Pier Adapter with Azimuth Bearing (900RPA)
This pier adapter was designed for very accurate and smooth adjustment of the azimuth angle without
loosening the lock-down knobs on the base of the mount. The top plate of the adapter rotates through the
900GTO mount’s full 15 degrees of azimuth motion. (It does not rotate through a full 360 degrees!) This
Rotating Pier Adapter is the ideal choice for portable setups as it makes azimuth adjustment so easy.
Upgrade your previous model 900 mount (any version) and enjoy the ease of use. Do a setup, followed by
a fine polar alignment at a remote site just once, and you will wonder how you ever got along without this
pier adapter!
The adapter includes two machined flat plates, four machined aluminum lock knobs with washers, a tall
version of the azimuth adjuster block, the center pivot screw and six 5/16-18 x 5/8 button head screws and
washers.
Attach to an Astro-Physics pier: Simply fit the Rotating Pier Adapter
into your Astro-Physics Portable Pier just like the Standard Pier
Adapter (900SPA) and fasten it from the side with the six screws and
washers provided. Make sure that the Azimuth Adjuster Block is on
the north side.
Attach to a flat surface on your own pier: The Rotating Pier Adapter
must fit inside another part and be bolted from the side. It cannot be
bolted through the top as you can with the Standard Pier Adapter.
For custom installations, we recommend our 900 Flat Surface
Adapter (900FSA). The Flat Surface Adapter bolts onto the flat plate
on top of your pier or tripod, then the Rotating Pier Adapter slips in
(just as it fits into our pier) and you fasten from the side with the six
screws and washers provided with the Rotating Pier Adapter. The
bolt circle for attaching the 900 Flat Surface Adapter to your pier is
7.230” diameter. The Flat Surface Adapter requires that the top
plate of your pier be at least 7 3/4” in diameter.
Using an ATS pier:If you plan to use an ATS pier, the O.D. of the
plate will need to be modified by ATS for an additional charge.
How does it work? Like most really good ideas, it is actually
quite simple. The bottom plate of the 900 Rotating Pier Adapt
fastened to your pier or tripod – it does not move. The Azimuth
Adjuster Block is attached to the bottom plate – it also does not move.
The top plate fits snugly into the bottom plate. Because of the tight fit,
the smooth bearing surface and the two recessed tension adjustment
screws, the top plate will rotate inside the bottom plate with absolutely
no play or wiggle. The movement, although velvety smooth, is quite
stiff – as it should be. The top plate has a slot through which the
Azimuth Adjuster Block protrudes. The slot allows the top plate to be
rotated through the 900GTO’s full 15 degrees of azimuth adjustment.
Your mount is fastened to the top plate and rotates along with the top
plate as you screw your mount’s Azimuth Adjusters against the
Azimuth Adjuster Block. The opposing Azimuth Adjuster Knob then
holds the whole thing in place once you are adequately polar aligned.
er is
Note #1: The two recessed screws (3/16 hex), shown by the arrows, adjust the tension between the two
plates of the Rotating Pier Adapter. These are preset to an optimal tension and should rarely, if ever, need
to be re-adjusted. You do not need to tighten or loosen these two screws as part of your normal polar
alignment routine.
Note #2: The Rotating Pier Adapter will work best with the Heavy Duty Azimuth Adjuster which is
standard on all 900GTO mounts produced after August, 2005 and is available as an upgrade (9AZKIT) to
older mounts. See our website for details.

Step by Step Instructions – 900 Precision-Adjust Rotating Pier Adapter
1. Line your pier or tripod up so that the adapter can point to the pole. To accomplish this, one of the
screw holes for attaching the Pier Adapter must face as close to north or south as possible. With
an Astro-Physics Pier, this can be accomplished with one of the legs pointing either straight north
or south as you prefer.
2. Securely attach the 900 Rotating Pier Adapter to your pier or tripod using the six 5/16 -18 x 5/8
button head screws and washers.
3. Rotate the top plate so that the Azimuth Adjuster Block is centered in the top plate’s adjustment
slot. (You may wish to “eyeball” your pier and adapter to be sure you are pointing as near as
you can tell toward the pole. If you are going to need to move the pier, it’s much easier to
move it now before you’ve added the weight of the mount to the assembly.)
4. Remove the four Pier Adapter Knobs if you haven’t already done so.
5. Make sure that the Azimuth Adjuster Knobs of your 900GTO are spread far enough apart to easily
fit the Azimuth Adjuster Block between them.
6. Carefully set your R.A. axis onto the Rotating
Pier Adapter. Use the adapter’s Center Pivot
Screw and Bottom Plate Alignment Screws to
help line up the mount on the adapter. The
alignment screws fit perfectly in the slot for the
rear Pier Adapter Knob. The mount should sit
flat on the adapter. The mount’s Azimuth
Adjuster should be centered over the adapter’s
Azimuth Adjuster Block. The slot in the
adapter’s flat plate should also still be centered
over the Azimuth Adjuster Block
7. Attach the four Pier Adapter Knobs and secure
them tightly.
8. Start your favorite polar alignment routine. If
you started with everything pretty well centered,
you will have about 7 ½ degrees of azimuth
adjustment in either direction. As you adjust the
azimuth with the mount’s Azimuth Adjuster
Knobs, the mount and adapter top plate will
rotate together.
(Remember to back off the opposite
Adjuster Knob to the one you are using
to rotate the mount.)
9. When aligned you must snug down the opposite
Azimuth Adjuster Knob to the one you were
adjusting to polar align. The two opposing
Azimuth Adjuster Knobs are what will actually
secure the mount’s azimuth position when polar aligned. If you leave the adjuster loose, the
mount could be knocked out of alignment.
This page was last modified on March 30, 2006
ASTRO-PHYSICS, INC.
11250 Forest Hills Road
Machesney Park, IL 61115
www.astro-physics.com, tel. [phone], fax [phone]