Many thanks. I gessed it but it is very good to know. Concerning the slew rate I always use the slower. Is there any one even slower?

Fernando

-----Original Message-----
Sent: Friday, March 05, 2004 13:15
Subject: [M]: Re: Counterweigth


> I need an expert advise. I have an LX200 10 inches in equatorial
> mounting. I plan to buy a second hand Megrez 102mm to mount it in
> piggiback to the LX200 OTA. I dont know the exact weigth of this scope
> but it is something not negligible. I think I have to put a
> counterweigth on the opposite side of the OTA. However I see two
> different effects. On one hand I see that balancing the tube is
> beneficial for the telescope mechanisms to be less stressed, but on
> the other hand I also see that the installation of a counterwegth is
> adding more weigth to the total structure that the mechanics have to
> move. So I dont know what is better to decrease the total stress that
> the telescope has to suffer. My worry is about maximizing the mounting
> life duration. I dont like to damage the mechanics. Any advise would
> be appreciated.
Total mass, is less important than getting things balanced. You can 'minimise' the weight needed, by ensuring that the piggyback scope is as close as possible to the main tube (this reduces the 'moment' it imposes). Yes, you do want to balance, and you need what is normally called a '3D' system. Ideally you have a weight below the tube that you can move in/out. Aim the tube vertically, and adjust this for balance. Then aim the tube horizontally, and adjust the position of the weight fore/aft along the tube, till the scope again balances. Get this right, and the system will be balanced at any point. You should also lower the maximum slew rate you use. This is recommended anyway, but the heavier the system, the more important it becomes, as it reduces the work the motors have to do to accelerate/decelerate. The force needed from the motors to accelerate to a particular rotation speed, depends on the rotational inertia of the system, and this will rise with the extra mass. Redu!
cing this is the most important factor for drive 'life' when dealing with a heavily loaded system.

Best Wishes

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