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Old 11-10-2007, 02:03 PM
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g__day (Matthew)
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Join Date: Dec 2005
Location: Sydney
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For simplicity what John just said is great advice. For best results I would advocate eliminate or minimise as many sources of error as can be achieved.

Your treatable sources of error include

1) polar alignment error - the better you have it - the fewer corrections are required, the fewer corrections are required - the fewer mistakes may be made

2) mechanical faults - backlash, poor mating of gears, imperfection of the gears. This is pretty common. If you can see you gear run through a complete worm cycle you can look for disruption to smooth flow. If the gears are too close together, have crud on several of the teeth or are not perfectly circular then they may stall or briefly lock then jump in places when enough torque has built up to force through the blockage. This is highly undesirable. You may be able to change the separation distance of the power gears (vs the worm and main gears) to avoid locks and stalls. However doing this increases the play and backlash so it's a balancing act that is ultimately determined by how clean, smooth and circular are your gears and how well machined are their teeth.

3) balance issues - close to perfect balance is preferred. A slight imbalance is of little concern - provided it is slight (e.g. maybe 500 grams of weight imbalance)?

4) Once the gears are as closely positioned and clean as suits, and polar alignment is excellent - then PEC training could and should help address bad PE curves so again PemPro or PrecisionPEC should help. Do an average of say 10 runs every 3 months to account for wear and tear on the gears.

5) Seeing errors - well I guess the light reach, seeing conditions, focal length of autoguider versus prime OTA, pixel size of your guide CCD will determine how well you can distinguish mechanical or alignment corrections from seeing aberrations. The main things I can suggest is the closer your guide OTA is in focal length to your prime imaging OTA and the finer your seeing and the finer your guide CCD micron size - the better you can determine and correct true tracking versus seeing errors.

Start simple and get more adventurous as you build up experience.

Last edited by g__day; 11-10-2007 at 04:16 PM.
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