Post by dirtydeeds on Nov 18, 2007 15:36:56 GMT
im aware that some here dont think the term "torsion box" for a shelf is a not correct in enginnering terms
but it does convey a construction principle that is more complicated than a sheet of mdf / ply cut to size
that aside i made a test piece to find out how strong a simple shelf could be
20x20 timber merchant pine "frame" and 6mm mdf top and bottom. no edging or hardwood to beef it up
all glued with titebond 2 and pinned with 18 guage pins. the frame isnt a pick up and walk around entity
260 wide 1080 long total thickness 26mm
it took my weight 71 kilos and the deflection was towards 4mm
on the basis i weigh twice as much as library books and the load was effectivly central it should be well within the maximum 2mm deflection that is visible over a 1m length
from the sagulator a piece of mdf same dimensions as above the calculation is a tad short of 14mm
but it does convey a construction principle that is more complicated than a sheet of mdf / ply cut to size
that aside i made a test piece to find out how strong a simple shelf could be
20x20 timber merchant pine "frame" and 6mm mdf top and bottom. no edging or hardwood to beef it up
all glued with titebond 2 and pinned with 18 guage pins. the frame isnt a pick up and walk around entity
260 wide 1080 long total thickness 26mm
it took my weight 71 kilos and the deflection was towards 4mm
on the basis i weigh twice as much as library books and the load was effectivly central it should be well within the maximum 2mm deflection that is visible over a 1m length
from the sagulator a piece of mdf same dimensions as above the calculation is a tad short of 14mm