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# Data for Minimum Torque Required with Shredder

This topic contains 8 replies, has 4 voices, and was last updated by  Steven Mosbrucker 2 years ago.

2

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..

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### In reply to: Data for Minimum Torque Required with Shredder

warrior
09/11/2017 at 19:01
2

1: Thin wide bottle top.. scale reads 6.818kg

### In reply to: Data for Minimum Torque Required with Shredder

warrior
09/11/2017 at 19:04
1

2: Thick small bottle top.. scale reads 6.789kg

### In reply to: Data for Minimum Torque Required with Shredder

warrior
09/11/2017 at 19:05
1

### In reply to: Data for Minimum Torque Required with Shredder

warrior
09/11/2017 at 19:06
3

WOOO HOOO!!

Thanks @timslab I will do something with these numbers.

### In reply to: Data for Minimum Torque Required with Shredder

warrior
09/11/2017 at 19:17
3

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?

### In reply to: Data for Minimum Torque Required with Shredder

warrior
10/11/2017 at 23:07
1

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.

### In reply to: Data for Minimum Torque Required with Shredder

hero
16/11/2017 at 21:10
0

This looks interesting… Subscribed 🙂

### In reply to: Data for Minimum Torque Required with Shredder

helper
19/11/2017 at 09:16
1

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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