Data for Minimum Torque Required with Shredder
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Hi everyone,
So @andyn had asked me a while ago to gather some info with my hand powered shredder to find the minimum amount of torque needed for the shredder to function.. I have finally put some time into getting this info (Sorry for the wait)
Now I’m no engineer and I think my system (with gears, flywheel et al) complicates matters a bit, so instead of doing the calculations myself I will share my findings and hopefully someone can work it out with better accuracy…
Method: In these tests I used only HDPE. The plastic was placed into the shredder and the blades turned until met with resistance. At this point I attached a bucket to the lever and slowly filled it up with water until the blade passed completely through the plastic. I slightly varied the thickness of plastics from a thin wide bottle top, thick fat bottle top and the thread of a detergent bottle.
Different materials and thicknesses can now easily be tested in future..
Quick calculation… The numbers all seem quite similar for different thicknesses and work out to approximately 60Nm at the shredder shaft, I was expecting more. Perhaps in normal running there would be plastic being compressed and about to be cut even though only one tooth is actually piercing at a time.
Tim, I don’t suppose you could try jamming the shredder full and seeing what’s the most amount of water you can get in the bucket before it cuts?
Thanks @andyn cool, yea that does seem low.. I’ve read in the past that 100Nm has been the estimated torque needed.
I suppose in functioning conditions there would be far more plastic between the blades. For sure, I’ll go chuck all that plastic into the shredder and see what I need to unblock it all.
180mm from crank center to force
turn that into meters .180m
turn measurement on scale to newtons kg*g = 9.81*6.818= 67N
first multiply that time the moment arm so 67N * .180m = 12Nm
5 to 1 ratio
5*12Nm= 60Nm of torque
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