ATM 18 Point Flotation Cell

["Alan Cairncross" <acairnx@onaustralia.com.au>]

I am designing an 18 point cell for my new telescope and I am in a bit of a
quandary. 
The mirror is 22"D, 2" thick and 100" focal length. When I put the figures
into Dave Chandler's CELL.EXE programme the support points are not equally
spaced around the circumference of the outer support point circle. However
when I work out the calculations in accordance with the formulas given in
the article "Mechanical Flotation of Mirrors" (p232 4th edition) in Amateur
Telescope Making Book One by John Hindle I find the support points are
equally spaced around the outer support point circle. The main difference
between the two methods is in the length of the connecting bar which is
7.1174" in Mr Chandler's programme and 6.948" in Mr Hindle's. If Mr
Hindle's figure is adopted and the base of the triangle is set to 4.15"
instead of 4.60128" then the outer support points are equally spaced as are
the inners.
Logically, I would think the support points should be equally spaced but I
may not be aware of something that decrees that the support points should
not be. If this is the case I would appreciate any advise that can be
offered.
Thanks
Alan.
acairnx@onaustralia.com.au