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Can a 5"x1 3/4" joist support a WM18
picclock:
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 ???
Best Regards
picclock
John Rudd:
Can you double up on the 1 3/4" thickness?
You might have a fighting chance then.....
hermetic:
If you can put a prop in to reduce the span of the joist, it will be fine, can you post a sketch of the set up?
picclock:
Hi hermetic
Sketch as requested. The garage was built over 3 different eras. This is the weakest section (and the newest), others have massive joists.
Best Regards
picclock
Lew_Merrick_PE:
--- Quote from: picclock on January 31, 2018, 11:46:27 AM ---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 ???
--- End quote ---
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?
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