(Clif) wrote in message . com...
(Mitch Alsup) wrote in message . com...
"Rich Lauzon" wrote in message ...
Never tried 6 points but isn't 9 point prefered for this size? Here is a
link to my telescope whith a nine point cell using marbles and three
triangular aluminum supports. Have a look and see what you think.
http://www3.sympatico.ca/richlauzon/telescope.html

According to PLOP, a 20" scope 2" thick can be supported with 6 points
and have 1/128 wave (or better) of mount-induced error. Tom Krajaci
has a 16" by 1.6" mirror on a 6 point cell working great.

A 4 point cell would be adequate for a 10" with reasonable thickness.

In addition, PLOP, also indicates that the better arrangement for 9
points is a ring of 9 rather than two rings of 3 and 6. Further PLOP
studies show that a ring of 8 and a single point in the center
outperforms all other 9 point arrangements.

I understand how to make the two rings of 3 and 6 supports support
their share of the load - just three triangles each of which carry two
of the points from the outer ring and one of the points from the inner
ring. If you then support each triangle at the right point,
everything balances and the mirror is supported properly. But how in
the world do you come up with an arrangement of triangles and lever
arms to make the correct load sharing between a center point and the
ring of eight points?
Clif
Mitch

Two triangles handle 6 of the 8 points on the outer ring. These triangles
are long and not very wide. The third triangle handles 2 points on the
outer ring and the center point. This triangle is wide and not so
long. To utilize the power PLOP brings to the game of mirror support
you (basically) have to loose the mental concept of pure symetry.
You also need to loose the concept that each point needs to carry the
same load.

Mitch