HumanPoweredDesigner
Well-Known Member
I'm working with basswood, which has a compression yeild stength of 4400 psi, tensile of 8400 psi, and not sure the shear, but guessing 4000 psi. Those are parallel to the grain. I want to use a dowel as a drive shaft. One must be 4 feet long and handle at least 80 foot pounds of torque, and the other 6 feet long and handle 20 foot pounds of torque.
I'm wondering if a 1" dowel would be strong enough for the first, and a half inch for the second. I'm ok at calculating truss strength and bends, but I'm not sure how to apply the torque thing. I know that circularly, some of the force is parallel and some perpendicular to the grain. I think perpendicular those shear strengths and tensiles drop to 250-400 psi.
I can attach some thick arms to the side of a short dowl and see how much torque it can take, but I'd like a ball park figure before I try 3 different sizes. Thanks in advance.
I'm wondering if a 1" dowel would be strong enough for the first, and a half inch for the second. I'm ok at calculating truss strength and bends, but I'm not sure how to apply the torque thing. I know that circularly, some of the force is parallel and some perpendicular to the grain. I think perpendicular those shear strengths and tensiles drop to 250-400 psi.
I can attach some thick arms to the side of a short dowl and see how much torque it can take, but I'd like a ball park figure before I try 3 different sizes. Thanks in advance.