I am building the shredder according to the drawings. The motor that i am using is very strong(2,5 Kw). However the shredding gets very aggressive. I am thinking that this is caused maybe by 2 thinks.
- The total distance between the moving knives and the fixed knives is 1mm which i believe is too big. In order to cut easily the knives should be very close together. If we think the example of scissors cutting paper, if the scissors’ cutting edges are not close together they can’t cut paper very well and the paper is chewed up. The solution to this would be the small fixed knives and the moving knives to be the same thickness and reduce their thickness accurately by some hundreds of a millimeter with a surface grinder or a milling machine so the total distance between the knives is very close but they don’t hit together. I understand that this may cost and Dave wisely designed the machines to be easily built with accessible materials and tools. However, I think this would decrease dramatically the cutting forces and increase the efficiency and shredded plastic’s quality.
2)My second and biggest concern is that the aggressive cutting is caused because the motor is not directly connected through a coupling to the shaft but through a chain and sprockets in order to double the speed and archive the desired RPMs as my motor is outputting 48RPMs.
What do you guys think? Did you had any experience with anyone of the problems? I think the 1st problem may not be so critical because Dave Hakkens and many others built it like that and it seems to work. I really want to have the shredder running nicely and i believe i am close.