Jump to content


Photo

Longer counterweight bar or more counterweights.

  • Please log in to reply
5 replies to this topic

#1 Bart

Bart

    Mercury-Atlas

  • *****
  • Posts: 2730
  • Joined: 28 May 2006
  • Loc: Somewhere near Charlottesville, VA

Posted 02 May 2011 - 12:40 PM

Should I lengthen the counterweight bar or add more counterweights. What are the pros and cons?

Anyone know where I can get reasonably priced counterweights?

Thanks

#2 Midnight Dan

Midnight Dan

    Voyager 1

  • *****
  • Posts: 11296
  • Joined: 23 Jan 2008
  • Loc: Hilton, NY, Yellow Zone (Bortle 4.5)

Posted 02 May 2011 - 12:53 PM

The mounts are rated at a certain maximum load - which is usually in addition to the included counterweights. So if you add counterweights, you'll have less of your weight budget left for your payload. So to me, a longer counterweight bar seems like the right way to go.

I'm no expert, but that's my 2 cents.
-Dan

#3 skywolf856

skywolf856

    Mariner 2

  • -----
  • Posts: 297
  • Joined: 25 Jan 2008
  • Loc: SE Michigan

Posted 02 May 2011 - 06:47 PM

The total weight of the c'weights used do not in any way add into the payload limits of the mount. For example on the CG5, theoretically you could have a 35 lb. telescope using 35 lbs of counterweights to balance at the maximum payload.
To answer the OP's first question, a longer bar would allow you to use your existing weights more efficiently, but you need to be aware of any mount swing clearances that may come into play with extreme positions.

#4 Mary B

Mary B

    Vendor - Echo Astronomy and Electronics

  • *****
  • Vendors
  • Posts: 3070
  • Joined: 21 May 2010
  • Loc: Minnesota

Posted 03 May 2011 - 12:11 AM

I would think vibration could creep in with a longer shaft.

#5 DaveJ

DaveJ

    Surveyor 1

  • *****
  • Posts: 1719
  • Joined: 07 Jan 2005
  • Loc: NE Ohio

Posted 03 May 2011 - 08:04 AM

I would think vibration could creep in with a longer shaft.


You're right, Mary; it does. I've tested this with my G11 (when I had it), my CGE and my LXD650. In all tests, I balanced perfectly with one weight at the extreme end of the counterweight shaft and then tested damping time at high power following a light tap on the focuser. I then balanced perfectly using two weights considerably closer to the fulcrum and tested again. With all three mounts, the damping time was noticeably less with two weights closer to the mount head. As far as I'm concerned, that proved the point for me. I'm now stuck with carrying more counterweights. :foreheadslap:

#6 Bart

Bart

    Mercury-Atlas

  • *****
  • Posts: 2730
  • Joined: 28 May 2006
  • Loc: Somewhere near Charlottesville, VA

Posted 03 May 2011 - 08:54 AM

Until I decide on which new mount I'll be purchasing, I'm going with the extension. It's cheaper than buying additional weights for a mount that I might not have for much longer.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics