Robert:

I think alot of people are having this problem. I know I was, until I
tried doing the fork arm alignment that was detailed here some time ago. I
was also having trouble with inaccurate GOTO's. The fork arm alignment
completley eliminated the problems. The problem appears to be that the OTA
is not properly aligned with the fork arms and the mechanical RA and DEC
axis. The adjustment is probably detailed in the archives and is a bit
finikey. I have refined the procedure a bit to be as follows:


Take the scope outside on a bright, overcast day
Place it on the tripod as level as you can get it in ALTAZ mode.
Remove the cover plate between the fork arms to expose the large RA Bearing.
Remove the OTA cover and the cover over the eyepiece entry hole - no
eyepiece.
Point the OTA straight up into the sky. Use the DEC setting circles to
indicate straight up.
Get a large coat or something to cover you and the scope - except the top
where the light is coming in
It will be dim but you should be able to see the cone of light coming out
the back of the scope.
Adjust the DEC axis to center the cone in one direcction over the large
bearing in the RA.
To make this determination of center easier I drew a central point and a
bunch of concentric circles
about 1/16 inch apart using a drawing package (you could use a compass). I
mounted this
using the cap screw that holds the bearing washer in place through the
center of the template.
Once centered in this direction check and align the Setting circles for 90
(or is it zero? can't remember)
I found mine to be off at least a couple of degrees.
If the OTA cone of light is also out of center over the bearing in the other
direction you need to loosen
the screws that hold the DEC axis shaft to the OTA on both sides.
You will notice on the edge of the mounting plate to the OTA a small hole
that has an allen screw in it.
If you turn this screw it will fine tune the position of the OTA with
respect to the DEC shaft plates.
Turn one side up and the other down until the light cone is centered over
the RA bearing in the other axis.
This adjustment is very tight and quite difficult but can be achieved.

This is the only way I think that guarantees the Optical train is aligned
with the mechanical axis.
I tried dial indicators on the outside of the tube to check for
perpendicularity but I found the tube out
of round and did not take into account that the optics are not necessarily
aligned witht the tube.

My scope now does GOTO's inside the FOV of a 12mm eyepiece over the full sky
and Polaris is in the proper place after doing a drift alignment followed by
a Meade alignment.

I presume this should be performed on a regular basis since handling the
scope - in my case putting
it in and out of the case - could eventually jog the alignment.

Try it - it should work for everyone who has louse GOTO's


Dave Sage


> Next, I decided to do drift alignment. After 1 hour of drift aligning I
had
>no dec drift for 30 minutes. However I noticed that when I calibrate on a
>known star and then slew the scope to polaris, polaris is not in the
>eypeice. If I adjust the long and lat on the wedge to center polaris my
>polar alignment is ruined. Something seems out of whack here but I don't
>know what. Anyone got any ideas?
> Thanks
>Robert
>
>
>
>

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