Hand cranked shredder
Constructed the shredder utlizing a winch crank up the rejected 3D plastic prints. Drive shaft had a turned key that fit the spring loaded crank and testing is going on at the moment. Would prefer motor powered shredder for THICKER harder peices (ABS/PLA) but it does well on other less brittle materials.
@anris when I read tire first I was like “what’s he at just using the tire” then it all clicked when I saw your super awesome artistic drawing 👍
The wheel could definitely work but instead of attaching weights, make a slit in the tire and using a funnel fill the tire with cement (or something similar) now we’re talking 😎
And now that I think of it when you pull the funnel out stick a bit of a broom handle in before it sets ⚡
Thank you @armbouhali
I will be looking at old markeds where someone might have something.
And thank you @cobhlanger
The page works just fine, and the video looks great where you can see the momental power from the wheel smashing the poor appels.
I thought about the old-school flywheel, and it seems like you need to be lucky to get your hands one one, so i think the route to go it to make one yourself.
Once again you shal behold my stunning drawing skills, as i have made a visual of how you might be able to transform a car-tire, or a wheel from a bike, into a flywheel by adding some (painted in orange) weights.
You propably need some iron and some welding, and not just rope as i have drawn 😉
Everything should hit 12-20 kg to be a decent flywheel in my opinion.
– What do you guys and girls think about this road of direktion?
@cobhlanger I hope everything works out for you!
I start seeing why you are also looking for a shredder oppotunity without a power caple and motor.
Have also been looking around for an oven for myself, and what i have seen, you can usualy get them for around 30 Euros. But room and power must also be taken into account.
If you are short on money, but gets a little time, then you can try out the tealight holders idea. It is a bit slow, but if you made yourself a bigger mold (like i did out of wood on the picture) And made it so the holes for the candles would be made instantly, you would have a small but allright production going on (Without the shredder!) And you will be able to make patterns that the shredded plastic cant do. (picture two)
PS, you are correct, it was an old shaft from a broomstic used as the shredder axis. 🙂
Thank you @cobhlanger ! I am glad to hear that the layout is nice, as i see that my safety most likely needs some help.
As far as my knowledge go, melting HDPE in the oven should not be considered any more dangerus then sitting in a livingroom with 5-8 candles burning.
I usaly just open the window or the front door to get some ventilation.
Please correct me if i am wrong, i have been searcing for info about this for the last 6 month 🙂
@anris i got onto the lads in the video (their based in my town) they got the machine from france
I’ll put a link up for it
Don’t know if it’ll work it’s a page on facebook
So i looked around, and found this topic:
I wanted to do something simulair, as the idea of having a flywheel, and some gearing would make hand power pretty consistant. This is a simple version of what me and my friend @clementhempel came up with yesterday.
Red = Gears from a bike
Green = The chain from a bike
Yellow = The handle
Pink = The flywheel with 12 – 20 kg, to create momentum
Blue = axis
Light blue = Plastic
Appreciate it buddy… to answer your question, ill get some video. Did an analysis for ABS plastic and calculated a torque of 81.6 ft*lbs (110.6 Nm). Though it works, i would strongly suggest at least a 1.5 hp motor to achieve some good amounts of shredding force for anything brittle or extremely hard. Our scrap was precut to gain these estimates so you kinda get the picture. Anyways, thanks again and ill be in touch with some sweet media of the little guy.
Kind regards Rhoy
@anris I simply act out of responsibility, using plastic waste is a whole world of new possibilities so every single idea interests me, whether it be in education, or for business purposes.
Algeria is ranked 13th among the world’s worst countries polluting oceans with plastic, and people started to notice the impact on the marine life more than a decade ago. For the time being, there’s no Precious Plastic workshop started in my country yet, so I plan to get the first one on feet either by doing everything on my own or by helping the first people who are ready to start. My goal is to spread awareness with an emphasis on education.
Making profit from waste comes as a way to motivate and mobilize people around the idea.
I’m very glad to be part of this creative community.
Hey again @cobhlanger, have been busy with school 😉
It depends on what stage in which context!
With plastic as an overall projekt, i would say i have gotten to an allright stage, and after lots of experiments.. and failures. I have gotten to a point where i can make a series of products in my parents oven, you can have a look at a few here in some other topics.
But if we stay on topic, with the shredder. I have gotten myself some lasercut parts in stainless steel for 336 euro. As you see i am still working on the engine 🙂
As far as other machines go, still none, but me and a friend are looking forward to build an injection machine.
Here are some pics:
Instead of using a crank for your shredder, you might try to hack a bicycle. if you can make a shredder with a longer arm, it would appear much easier to tear apart some material.
Why not try and convert a bike motor to power a shredder ? Though being fuel powered means more pollution but I think it’s a good alternative if the motor is powerful enough 😉
What if you add a reduction gearbox in the middle to compensate effort with more crank turns ?
Good luck and keep us informed about any news 🙂
Thank you so much for the fast response!
I did some quick math with your calculated torque:
I am going to use an arm that is 1/2 meters long so the power to turn it will be:
110.6 N*m/0.5m = 221,2 N
And to calculate how much weight aka armpower that is needed to turn it, we devide by the gravitational acceleration:
221.1 N/9.82m/s^2 = 22.5 kg
That is still quite tough to grind, but i looked up the (Tensile Strength, Yield) i gues its a number for how hard the plastic is to tear apart. For ABS and HDPE, as i am going to shred HDPE primarily.
6160 – 6500 psi Tensile Strength, Yield (ABS)
4350 psi Tensile Strength, Yield (HDPE)
4350 psi / 6500 psi = 0.67
22.5 kg * 0.67 = 15.1 kg
Looking forward for the video so that i can have a look at what you are relly shredding, thanks for the help so far, it was very helpfull!
Best – Mathias
Thanks for the tip @cobhlanger
I have one center nearby where there’s a chance i might get my hands on one.
I gues the combi will do as long as it’s capable of heating the plastic up to around 180 ‘C.
(and not just microwaves it.. I have no clue what happens when you microwave it.. Propably nothing?)
@armbouhali your plan sounds amasing, i hope your Precious Plastic workshop in Algeria works out!
@rhoy2468 How is the video of the hand cranked shredder comming along? 😀
Try the recycle centres @anris i know round here whem people do up their kitchens they throw out their ovens even when there’s nothing wrong with them.
I wonder would a combi microwave do the same job as that would be an easier set up.
Good thinking on the broom handle
Keep up the good work @armbouhali
I’d say those machines are as rare as hens teeth pure old school I’d say but then again ya prob could cast something simular. I’ll have a look and see what I can find
I’m really wanting to stay clear of using a motor for both keeping the operating cost down as well as not been tied into a 1 or 3 phase location, and I’m loving all of your ideas. But what about a bit wheel crank to act like a flywheel once ya get momentum going you should be able to shred anything.
here are some calcs I did in another post for a bike powered shredder;
Well there are a few governing equations to sizing flywheels for this application
there are a few variables that are listed bellow:
1. Material that is being cut properties
2. Material that is being cut cross section
3. Flywheel design
4. Flywheel Material
So onto the equations:
First rotational kinetic energy units (Joules)
I = rotational inertia (moment of inertia) has to do with flywheel design
W = angular velocity
to find I just design a flywheel in a standard cad program and it will usually tell you what it is at center of mass
W is found by taking the tangential velocity on the outer rim of the flywheel and dividing it by the radius of the flywheel W = v/r
Next value that is important is the Tensile Impact Strength value of the material.
This is looked up from a table of your material for HDPE it is around 243KJ/m^2
i designed this bowl on cad (not designed for flywheel)
and looked up its highest moment of inertia on cad which = .0004647 Kg m^2
r = .109
i need to find how fast i must rotate the flywheel to cut the material
impact strength of HDPE of 243KJ/m^2
and a cutting cross section of 1 inch x 1 inch or .00064516 m^2
impact strength needed is 243,000 * .00064516 = 156.77388 Joules of KE needed
so solving KE equation for velocity
1/2(W^2)(I)=KE W= V/r 1/2(V^2/r^2)(I)=KE ((KE(r^2)(2))/I)^(1/2) =V
((156.77388(.109^2)(2))/(.0004647)))^(1/2) = 89 m/s or 200 mph lolz
a more important problem would be to solve for I as most people can pedal at 10mph
because you are solving for I you can determine what you need to model and using what material
to solve for I
however as you see you would also need to know the radius of your part as well so this equation has 2 unkowns.
basically the r would be limited by the machine that you are going to use to make the flywheel or the material you can get your hands on
you would then design around that.
I did some of the math for a 20Kg cast iron lifting plate
that would get you pretty close to cutting that 1 inch by 1 inch cross section
however that is only 1 tooth so you would need a 20kg plate per tooth /2
so if you have 12 i would do 6-8 20kg plates so 160kg of weight for flywheel.
reason why you would need a plate per tooth is that your flywheel would stop after only one tooth cut but you want to keep going indefinitely so you will need to have energy to spare so that you just spend energy keeping the flywheel up to speed.
so a 20kg cast iron lifting plate would be a good idea.
here is the original thread. https://davehakkens.nl/community/forums/topic/bicycle-shredder-costs-work-in-progress/
I’ve been following your project on hand cranks. I am not a metal worker but I am very interested in raising money & distributing these in various countries thru a non profit organization to watch over & manage. When the kinks get worked out, many hands across the globe gathering & washing plastic could make a dent. What is your goal? I’m looking for help to get further down the road.
@anris that’s good to know about the fumes off HDPE I’d like to give your candle holder a go soon but I’ll have to wait till herself is not around or she’d kill me. I was thinking of getting a scrap oven or a cheap 2nd hand one but hooking up to electric could be a problem as I’m sure they use a hefty power cable.
I’ve always wanted to run my own business and I’ve been close a few times. I like to look for an unusual business opportunity as it would interest me more and the beauty is I’m 4yrs off my military pension which will give me the flexibility to take chances on a business venture.
My problem at the moment is just time (+ money) I have an almost 3yr old daughter, just bought a derelict house that needs doing up and I’m studying business and accountancy in the evenings as well as the girlfriend working mad hours trying to progress her business.
@cobhlanger I an at stage zero, gathering enough information to get started with less available options in my country and more difficulty to crowdfund a starting budget. That’s why any cheaper options with more available materials are more than welcome in my case 🙂
About using a mask/respirator when melting plastics, one might need one when experimenting new things, or when dealing with plastics of different sources. Some plastic types such as PVC have toxic fumes, while other plastics known to be safe might simply contain some toxic additives wاhich evaporate when heated/burnt. So yes you need a mask near you to also deal with any possible hazard.
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