Considering a larger mill but will have to install myself. Weight all up is 160 kgs but I'm hoping to hoist it up in bits using the joist and a pulley or similar. How much weight can a 5" x1 3/4" joist take ? about 3-4ft from the wall. Any idea ???
Picloc --
The stress you will need to worry about is the
extreme fibre stress in ths joist. Assuming that you will
hang the pulleu some distance below the Joist's horizontal centerline, the thing will be controlled by the
Area Moment of Inertia. That is (for the beam itself) b*h³*12 or (1.75)*(5^3)/12 = 15.625 in^4. If the
axis of your pulley is located (say) 5 inches (below assumed) from your Joist's horizontal centerline, then
add r²A (64 * 7.5 = 480 in^4) to the 15.625 in^4 (for 495.625 in^4 total). As I recall, your Pulleu will be located 1 m (call it 40 inches) from the "support" for the Joist. Thus, yopur "applied bending moment" is (160 kg)*(2.205 lb/kg)*(40 inches = 14,110 lb-in). Your
fiber stress will be S = mc/I = (14,410 lb-in)*(8 inches)/495.625 in^4) = 233 lb/in². Most structural timbers here in the U.S. have an
allowable fibre stress in the 1600 lb/in² range. Does this help?