Re: [ATM] How to find Centre of Gravity of an existing telescope

[dave w <daze39@earthlink.net>]

Bruce MacDonald wrote:

> Questions:
> How does one go about determining the CoG of the telescope/mount combination?


"Center of gravity" is another word for "balance point" - the position where there are
equal mounts of the weight on either side.

If you can grasp the assembled telescope+mount with one hand on each side, find
the position where it rises equally rather than tilting forward or back as you
start to lift it up.

Another method, for a telescope with a flat base, would be to place a wooden dowel,
piece of broomstick, etc. under the base on a flat surface, and find the position
where it is balanced and not trying to tip one way or the other. That is, if you
put the rod under the front edge of the base, it will want tip back so the back
edge is touching the surface, but as you roll the base forward over the rod, you
will reach a point past which it wants to tip forward instead - that "crossover"
point where it just balances evenly is the "center of gravity".

With the "Dobsonian" style mount, the tube assembly itself will normally be balanced
at the axis of the altitude bearing system (so you can elevate or lower the tube
and it will stay put without trying to tip one way or the other); if there are
heavy accessories (such as batteries for electrical gadgets) mounted to the
front or rear of the base assembly, that could shift the balance point of the
complete instrument.

-dave w

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