I really wanted to give Polar alignment a try to at least learn about it so I purchased the Celestron equatorial wedge (Cat #93658). After a few weeks of messing with the alignment procedure I was able to get accurate go-to performance from my Nexstar 8SE Alt-Az mount. Since then I have refined my alignment procedure and I though I would share it with others that may be interested in trying to polar align their SE mount. The following procedure is the one I developed to be used with the Celestron equatorial wedge and has worked on my scope ever since:
To start off I needed to make a few adjustments and modifications to my scope and mount. I decided to open up the Alt-Az head cover and adjust the thrust bearing nut assembly to assure that the mount arm was not "rocking" on the nylon bearing pads. This problem can cause alignment errors and make the go-to accuracy erratic. The adjustment was performed while the scope was mounted onto the wedge/tripod and the wedge was angled at 34 degrees or so (this is my local equatorial angle). Mounting the scope on the angled wedge will apply the proper side load to the SE mount and allow for proper adjustment of the thrust bearing nut. The stock bearing preload on my scope was low enough that the scope mount was "hanging" loosely and could be rocked back and fourth. This basically means that â€œout of the boxâ€ my scope would not work with the Celestron wedge. I fixed the problem by tightening the thrust bearing tension nut to just enough preload as to not have any play but loose enough as to not promote rotational "sticking".
Once the Alt-Az mount was â€œtuned upâ€ I marked out calibration marks on the mount to indicate optical tube assembly (OTA) positioning. This would prove to really help aligning the scope and make the north equatorial â€“ EQ autoalign alignment a breeze. I did this first by marking precise altitude index marks permanently on the mount arm. These are the same marks that are indicated by the factory stickers at the top of the mount arm. The problem is that these stickers shift even when touched lightly as they have poor adhesive under them. A permanent mark was needed to replace these stickers.
I placed the Nexstar mount with the scope attached on an extremely level surface (without the tripod attached) and used a torpedo level to align the OTA horizontally. I leveled the OTA by placing the torpedo level on the top of the OTA and then double checked it by placing the level on the bottom of the tube as well. I then used a hobby knife to make small notches (as seen in the top photo below) that line up at the precise index angle (which has the OTA parallel to the mount base bottom). I then positioned the tube perfectly vertical (perpendicular to the mount base bottom) and made a matching notch (on the round OTA dovetail clamp unit) to help aid in polar alignment.
Now all I needed was a meridian â€œindexâ€ indicator that would help me locate the precise meridian for alignment. I did this by carefully leveling my assembled tripod with the wedge and mount/scope attached (and angled to 34 degrees for my location). I then used the torpedo level to level the wedge base and then precisely plumb the OTA vertically in both axes (pointed at zenith). This gave me the location at which to notch the base and base cover with my meridian index indication marks. I made my notches at the upturned side of the Alt-Az mount base (as seen in the middle photo below)
To help aid in tripod setup time I added a â€œbullseyeâ€ level (see the bottom photo below) to the wedge base that eliminates the need for using a separate level each time I set up the scope. For this I used a 7/8â€ bullseye level that I had purchased from McMaster-Carr (Cat #22325A11). I drilled a recessed hole in the EQ wedge base in where I epoxied the level into (making sure to calibrate the levelâ€™s position to a torpedo level before the epoxy cures). The bullseye level makes polar alignment much easier by confirming that the wedge is level insuring that the go-to alignment will be accurate and consistent.
Continued on the next postâ€¦â€¦.