Jump to content


Photo

fine azimuth adjustments for polar alignment

  • Please log in to reply
10 replies to this topic

#1 orlyandico

orlyandico

    Fly Me to the Moon

  • *****
  • Posts: 5637
  • Joined: 10 Aug 2009
  • Loc: Singapore

Posted 21 November 2012 - 08:36 AM

hi all

does anyone have hints on how to do really fine polar azimuth adjustment?

i think the typical azimuth bolts are 1/4" - 20tpi or similar. If the polar base is 5" in diameter, one turn of the azimuth bolt would be 1.15 degrees, so the typical 1/4 turn would be about 0.3 degrees or 18 arc-minutes.

Given that, how can one get a really close alignment to the pole?

secondly, often the mount base binds, so when you turn the azimuth bolt, the base doesn't rotate. when you turn it some more, it then rotates (by a large amount).

so these two issues make a really good polar alignment difficult.

any ideas? is there some material one can put between the mount and its base to lessen friction and make azimuth adjustments smoother?

#2 rmollise

rmollise

    Hubble

  • *****
  • Posts: 15688
  • Joined: 06 Jul 2007

Posted 21 November 2012 - 09:24 AM

The average bolt system is more than sufficient to get you on the pole.

#3 themos

themos

    Sputnik

  • -----
  • Posts: 40
  • Joined: 01 Apr 2008

Posted 21 November 2012 - 09:25 AM

I've found the kind of plastic that is used in milk bottles is a good material to use.

#4 DaveJ

DaveJ

    Surveyor 1

  • *****
  • Posts: 1759
  • Joined: 07 Jan 2005
  • Loc: NE Ohio

Posted 21 November 2012 - 02:20 PM

Is there some material one can put between the mount and its base to lessen friction and make azimuth adjustments smoother?


Here you go: UHMW sticky-backed material. A friend and I tried this stuff and it made a *world* of difference. It's almost as if the AZ was on roller bearings - it made that much difference. And that's with the mount tightened down hard before making the AZ adjustments.

#5 Tom Andrews

Tom Andrews

    Apollo

  • *****
  • Posts: 1445
  • Joined: 25 Jan 2007
  • Loc: Albuquerque, NM

Posted 21 November 2012 - 10:52 PM

is there some material one can put between the mount and its base to lessen friction and make azimuth adjustments smoother?


I used a bar of soap and rubbed it on the tripod head where the mount base sits. Now with the mount tightened as much as I can, adjusting the azimuth is almost too smooth! Works great, cheap, clean, doesn't attract dust and when it wears off, do it again.

#6 Phil Sherman

Phil Sherman

    Surveyor 1

  • -----
  • Posts: 1569
  • Joined: 07 Dec 2010
  • Loc: Cleveland, Ohio

Posted 21 November 2012 - 11:01 PM

My Atlas mount was very difficult to adjust in azimuth until I added a homemade "bearing" to the tripod where the mount mated with it. A trip to the local hobby store and a few bucks gave me some thin styrene sheets. I took one and cut out a ring that was attached to the tripod with contact cement. The mount now slides easily when adjusting the azimuth knobs.

Phil

#7 orlyandico

orlyandico

    Fly Me to the Moon

  • *****
  • Posts: 5637
  • Joined: 10 Aug 2009
  • Loc: Singapore

Posted 21 November 2012 - 11:52 PM

good one Tom.

The UHMW is probably the posh solution, styrene is the low-end one and the soap is the lowest.

Will try the soap first. :-)

#8 Tom Andrews

Tom Andrews

    Apollo

  • *****
  • Posts: 1445
  • Joined: 25 Jan 2007
  • Loc: Albuquerque, NM

Posted 22 November 2012 - 11:33 AM

Bar soap is an old school remedy that I learned from my dad and is good for many things . He always used it on screws to make them go easily into wood and anything else that needed lubrication.

#9 mclewis1

mclewis1

    Thread Killer

  • ****-
  • Posts: 10994
  • Joined: 25 Feb 2006
  • Loc: New Brunswick, Canada

Posted 22 November 2012 - 11:53 AM

CG-5/EQ-5/6/Sirius/Atlas/CGEM and similar mounts have a relatively small contact area between the mount and tripod head and a single central bolt, all of which can make the azimuth movement problematic.

Removing any loose paint, smoothing the upper surface (lower too but that can be quite tough to do), and adding plastic/synthetic "bearing" or a little lubricant all help the situation, sometimes dramatically. But you need to be careful about adding anything in between ... it should be as thin and strong as possible or you may experience some tilt before the center bolt is fully snugged down.

On heavier mounts like the CGE and CGEPro there is a different setup to attach the electronics pier to the base of the mount. It has much more surface area and usually only requires a very thin film of suitable lubricant (grease) to maintain the ability to move in azimuth without binding or tilting. On the original CGE the cam style Az adjustment bolt doesn't offer a very fine movement capability, but there is a 3rd party solution that adds a fine screw type of adjustment (from TPI Astro).

#10 orlyandico

orlyandico

    Fly Me to the Moon

  • *****
  • Posts: 5637
  • Joined: 10 Aug 2009
  • Loc: Singapore

Posted 22 November 2012 - 12:47 PM

in my case the mount is an AP600.

i figure before blowing a huge (for me) wad of cash on a Mach1 or Tak to fix my declination guiding issues, i should just try to get a perfect polar alignment so i don't need to guide in declination.

this has proved troublesome because of the rough azimuth adjustment.....

#11 Phillip Easton

Phillip Easton

    Ranger 4

  • -----
  • Posts: 323
  • Joined: 24 Dec 2010
  • Loc: DFW

Posted 23 November 2012 - 06:14 PM

On mye iEQ45 I sanded off the paint on the contact surfaces and then apply a lite coat of SuperLube.

http://www.the3dwiza...rface-modifi...






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics