EQ Mount complete balancing procedure.

[Coastliner]

Hi All,

You find me slightly irritated this morning, as I am trying to balance my eq mount and don't seem to be able to get complete instructions.

I fully understand that I need to balance dec first, by having the ra horizontal and locked, then move the tube fore/aft in its rings until is is balanced. Then lock dec, unlock ra and move the counterweights to balance horizontally.

Essy.

At this point I am told that I can put the ota in any position and it will stay there.

No it won't, not with a DSLR, a RDF and a finder/guider attached to the ota.

These instructions do not take into account the fact that the center of gravity changes as you move the scope, so much so that it can be a struggle for me to get the tube into the home position (vertical, pointing North). When I have it in the home position it is fighting to fall one way, I feel it is putting too much load on the clutch/gears.

Now, I feel that I need to rotate the tube in its rings when it is in the home position to stop it fighting to fall one way or the other, but I can't find anywhere that explains this.

But if I get it balanced in this position, it falls out of balance when it moves away from home, so it will not stay put in any position.

Am I being OCD? Does it matter? Can someone point me to instructions that take the OTA rotation into account?

Thanks,

Mr Grumpy.

[StuartJPP]

It can be a bit tricky finding perfect balance in all orientations (all axes). Every little bit of imbalance will show...for example the battery compartment on a DSLR will impart some imbalance.

Have you watch the astronomy shed videos on YouTube that cover balancing (there are a couple)?

 

 

[Coastliner]

I think I may have managed it.

1) Counterweights horizontal.

2) Balance the tube til horizontal.

3) Balance tube v counterweights.

4) Move to home position (weights down, tube pointing North.

5) Rotate the tube in the rings til it is happy to sit upright in the home position.

6) Move weights and tube to horizontal again and rebalance. Repeat from 4) til happy. Three iterations nailed it.

Does this sound right?

[SonnyE]

I don't try for "Perfect Balance" with mine. I find that PDC (Pretty Danged Close) is good as it needs as it pre-loads the gearing to some extent. (My backlash is minimal however, and my top end is rather light)

But you do need to have everything in place before beginning your adventure into frustration. You cannot add, or change, a camera for example without affecting the balance.

I went to far as to drill detents into my Vixen bar once I settled on my configuration. That way my clamping screws fall into the exact same spot from day to day when attaching my telescope assembly. (My Vixen bar is of solid aluminium)

I learned long ago that Perfection is a lot like hunting Unicorns. Fun, but unlikely to find. So my top assembly is slightly tail heavy.

You will find your Unicorn... ;^)

[Coastliner]

I guess you are right, but I found that without rotating the tube in the rings it was a real fight getting the tube to stay upright in the home position. I have now remembered that you can spend a lot of time getting the balance right only to ruin everything by moving the counterweights in order to make the mount East Heavy to eliminate backlash bounce.

[ollypenrice]

You're finding that dynamic balance is imperfect. This is because, if you point the scope at Polaris and stand behind it looking north, one side of the scope is heavier than the other. Maybe a finderscope or camera assymetry or whatever. An imbalance at this level is totally trivial from the mechanical point of view of your clutches and gears so don't worry about that. It will probably be trivial from a guiding point of view as well but if you have some backlash then it might not be. It might even be your cabling. I would see if the mount does what you want it to do and forget about it unless you discover a backlash issue.

Olly

[Sevo]

I have a question...

Does the imperfect balance impact Periodic Error?

I have this strange effect when my 8 inch SCis loaded with autoguider and DSLR camera.

Even the PE training does not help.