@uncle_bob: Based on some of the equations I posted above you could make the screws about 34" long. (That would have the same max deflection as the 3/8" ones I have already tested.)
Here is an approximate rule of thumb for what I consider the edge of acceptability. I would encourage people to err on the side of caution.
L=ACCEPTABLE SCREW LENGTH
d=ROOT DIAMETER OF SCREW (The diameter of the screw if you remove the threads. For instance, the 3/8" screws I tried have a root diameter of 1/4".)
L=150*d^1.33
--OR--
d=0.023*L^0.75
*Units should be in inches for these equations.
[attachment 22713 mate_screw_torq_carbon.jpg]
So for the 7/16" screws with a root diameter of .327" you will end of with a max safe length of about 34". If you bump up to the 3/4" screw then you can use 5' screws. If you bump up to a 1" screw you can make it 8.5' tall. (For fun I priced this last one. It comes to less than $2500 for the whole printer. For 5 times the cost you can make a printer that has 75 times the volume.)
Here is an approximate rule of thumb for what I consider the edge of acceptability. I would encourage people to err on the side of caution.
L=ACCEPTABLE SCREW LENGTH
d=ROOT DIAMETER OF SCREW (The diameter of the screw if you remove the threads. For instance, the 3/8" screws I tried have a root diameter of 1/4".)
L=150*d^1.33
--OR--
d=0.023*L^0.75
*Units should be in inches for these equations.
[attachment 22713 mate_screw_torq_carbon.jpg]
So for the 7/16" screws with a root diameter of .327" you will end of with a max safe length of about 34". If you bump up to the 3/4" screw then you can use 5' screws. If you bump up to a 1" screw you can make it 8.5' tall. (For fun I priced this last one. It comes to less than $2500 for the whole printer. For 5 times the cost you can make a printer that has 75 times the volume.)