Mechanical Fuse/ Shear Pin

[rmw125]

Ive searched a lot of these forums and i'm still having trouble designing a shear pin. I have an alluminum plate in which i would like to pin a interior housing as a fail safe. The housing is centrally located with a force pulling straight out( perpindicular to the plate) and is also aluminum.(Sketch Attached) I've estimated that i would like the pins to break at 300lbs, with 3 pins. Im unsure of the material i should use, plating, and how i should neck down the pin.
Thanks for all the help
-Ryan

 

[BobM3]

Why not buy standard shear pins? Their breaking strengths are listed by their manufacturers (Spirol, Vogelsang are a few).

 

[rmw125]

Thanks, ive been looking for a manufacturer for these with no luck untill now.
-Ryan