I think this is a very basic question, so I apologize in advance if this seems too elementary! I am assembling a project and I need to mount a number of heavy sub-assemblies to a 1/2'' aluminum plate. I believe the alloy is 6061. The heaviest item weighs 20 lbs and will be attached by two screws. I am using 1/4-20, SS, socket-head screws and the head must not protrude above the bottom surface of the plate. The "items" to be mounted on the top surface of the plate are drilled and tapped to accept the 1/4-20 screws. The heads of these screws measures 0.222 in height, which would require a counter bore of at least that amount. This depth would represent approx. 44 percent of the material thickness. When the project is completed, the vertical orientation of the plate will cause the screws to be in shear.
My question: does this leave adequate material for torquing down on these screws. Is there a generally recognized method (rule of thumb) to establish the maximum depth of a counter bore, before risking tear out of the material?
Thanks in advance.
Frank
My question: does this leave adequate material for torquing down on these screws. Is there a generally recognized method (rule of thumb) to establish the maximum depth of a counter bore, before risking tear out of the material?
Thanks in advance.
Frank