ATM Alternative to Sling

[Bob Van Deusen <bobmsb@prairie.lakes.com>]

I'm waiting for my 12" blank to arrive and reading thru Berry's book on 
big Dobs. Last night I read about mirror cells. They recomend a 9 point 
cell with sling for a 12". They also describe metal posts mounted on the 
outside of the cell, around the mirror.  I've built two 8" and used a 
wood disk for a cell. My understanding is, this gives a three point 
support and is sufficent for a full thickness 8".  I have three metal 
posts on the outside of the disk and run electrical tape around the 
mirror and posts to keep the mirror from coming off the cell. Would this 
be an alternative to a sling in a 12" mirror?
I wish my blank would get here so I can start working and stop thinking.
TIA
Bob Van Deusen
Lewisville, MN