Counter weights

[Marvin Jenkins]

Give me your thoughts on the correct use of counter weights. Obviously we all know they are for balancing the mount, but I see lots of variation to position and number.

I have seen some setups with more than one weight but positioned very close to the mount. Other people using a single weight far towards the end of the bar. I would have thought that using the smallest amount of weight to acheve balance would be right, but perhaps there is something I am missing.

This doesn’t affect my set up yet, neq5 130 newt. The mount came with two weights but with my small mirror I only need one weight at about the half way point.

Is there any rhyme or reason or is it all personal preference.

[lenscap]

Hi,

By using more weight, closer you will minimise the moment of inertia and therefore minimise the acceleration loads and wear & tear on your motors & drive train.

[mikeDnight]

I suppose that if you want to keep a set-up as light as possible, then using a lighter weight at the end of the counter balance arm is ideal. If however you want to add/swap & change scopes or accessories as the night progresses where the balance might change significantly, then having an extra weight or having adjustability in the weight being used is preferrable.  If however, the mount is set up permanently and the same scope is to be used every time, then there's an argument for using a heavy weight as close to the mount body as possible. The balancing arm could then be shortened for compactness, and reducing potential vibration issues.

[GazOC]

More weight/ nearer the mount seems to be the conclusion when this topic gets brought up. 

[Skipper Billy]

3 hours ago, lenscap said:

By using more weight, closer you will minimise the moment of inertia and therefore minimise the acceleration loads and wear & tear on your motors & drive train.

Good explanation plus the flexing of the counterweight shaft is minimised.

[Marvin Jenkins]

Thank you. Sounds sensible, I will bear all this mind when I scale up my gear.

[hughgilhespie]

Being a tad on the large size, using heavy weights close in means I can get away with a shorter counterweight bar. This is a blessing in my 2.2 metre observatory as I can navigate past the telescope without having to breathe in.

Regards, Hugh

[Gabby76]

A quick way to calculate counterweights: 

http://www.robincasady.com/Astro/WeightCalc.html

[Marvin Jenkins]

Thank you very much for that link, I will file that away for the day when I scale up and this becomes a problem that needs calculating. Hopefully sooner rather than later.

Marv