Re: ... and daytime polar alignment

Tyrel Smith

I guess I just don’t understand the need for a level, and especially the need for a level each time you tear down/set up, when some very simple indices on the mount make life so simple. Placing a flat-bottomed level on a round counterweight shaft is not that accurate. One with a v-bottom or groove of some sort, mabye more so. I’m more intrigued by this need for an extreme level of accuracy setting up your park position with a level, when all that effort is seemingly nullified when you do your first goto and recal (of if you are imaging, your first plate solve/sync). If you do a goto and recal, then send the mount to your preferred park position, it should then be in the most accurate representation of that park position, regardless of how well you leveled the counterweight shaft when you set up your preferred park position. My understanding is that the only thing accomplished by a precise predetermination of your park position is the accuracy of the very first goto command. Do I have a misunderstanding of how the mount behaves. I’d like to be corrected if that is the case. I could have some previous mount logic creeping in.

Having some indices on your axis has the benefit of being able to unlock the clutches and then being able to relatively accurately (the width of a pencil mark) put the mount back in the park position without a trip to the toolbox.

Seriously, I have never once put a level on my Mach1 counterweight shaft. I did one platesolve/sync, sent the mount to park 3, put a piece of tape across the two axis with a pen mark, cut the tape with a razor, and moved on. At the end of my imaging sessions when I send the mount back to park 3 it lines the pen lines up every time. I either unpark from last position, or line up the marks and unpark from park 3. If I am missing something, someone please let me know. I’m always looking for ways to improve my setup. If using the level is zen/ritualistic thing for some folks, thats ok by me. There is no judgement in this dojo! 

On Apr 21, 2019, at 13:16, 'Joseph Zeglinski' J.Zeglinski@... [ap-gto] <ap-gto@...> wrote:

    Have a look at my DYI Bubble Level in this group’s FILES section – Because the bubble’s travel is a “foot long”, it is far more precise than my STARRETT.  The “pipette” is already marked out with fine millimetre divisions by design, since it is already precisely marked for measuring “millilitres” in the lab. That’s “lab accuracy” as good as for a machinist’s use.
    It also cost me about $2 (for a used pipette – they are disposable, easier to find), compared to a Starrett costing over a hundred (?) dollars, and is far easier to read a large bubble on a long path. Because it has so much more fluid, the bubble starts to travel at just a hare’s breath of a tilt, compared to the smaller tube in a machinist’s level. Besides, the pipette is Plexiglas, or tempered glass, (lab use safety concern), so it won’t break when dropped or banged in travel,  as my old STARRETT glass tube did.
    you can fill the pipette bubble level with turpentine, radiator cold weather antifreeze, or with (coloured) winter windshield wiper fluid, for outdoor cold temperature use. You can even add an LED lighting to the tube top or ends for easier night use.
    See PDF article  and photos:   DIY BUBBLE LEVEL TOOL.pdf  ( ASTROJAZ - Jan 31, 2016)
Joe Z.

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