Hi, name is Hunter.
I’m a year 11 student in systems engineering units 1 & 2
my project i plan to make is a automated can crusher that detects oversize can and steel cans into different bins only crushing aluminum can and then putting them in there own bin as well. the main force of crushing in where i am having issues i have yet to test the force i need (the system will also crimp the side of the can before main crushing to reduce force needed) in order to crush the can the system will be mainly powered by a level driven my a pulley or chain system from a motor this allows me to time the events based on where i attached things to the chain the issue i have is finding a motor that will be able to deal with the stresses from the force of the can i can adjust the lever to change what torque is needed from the motor but it will still feel the total force of the can just over a longer period. is any body able to help me find a way to achieve this? cause a small dc motor will not suffice it needs to have a bit of oomph to it, even if you know of some products that i might have around i can scavenge the parts from, or is there other way i can power the lever? i don’t have a massive budget so i’m not looking to spend $60 on a motor.
Kind Regards,
and thanks in advance,
Hunter Townsend
Quite the project you’ve set out before yourself! I wish I had the opportunity to do systems engineering during school I had to wait until Uni. You have a couple of questions so I’ll attempt to address all of them one by one.
I’m sure you’ve had the same experience as me growing up where you could step on an empty can with all your weight and it will just about hold your weight. Looking further into it at about 65KG of stable weight from above will cause an empty aluminium can to crush. However, crimping or slightly deforming the can before crushing will dramatically lower that value as it breaks the structural integrity (definitely a good idea if you can’t get your hands on a semi powerful DC motor).
In defence of a small DC motor it could reach the torque required if you geared down the system to a high extent (however your system would be slow, the tradeoff). Since you’re okay scavenging, bicycle component such as the sprockets, hubs and chains offer a great way to gear reduce to increase torque. Another idea is planetary gearboxes from discarded electric drills could be used.
Finding a DC motor is the most challenging part but if you can find a discarded treadmill they run off 1-2 HP DC motors which would be above and beyond the demands required for your system (the hardest part would be making the motor run slow enough).
In terms of powering the lever may I offer a suggestion of instead using a piston like mechanism to crush the cans. Your turning rotational energy into a linear ‘Crushing’ motion and this would be easier to implement than a lever mechanism. But please be careful and don’t trap your fingers in the system! I’d feel terrible.
Hi Tim,
Thanks for your quick reply.
I am aware you can stand on a can if you get it right i, uh got some injuries doing that…
I am using a level as the crushing mechanism as it applies force at a more diagonal angle also reducing the strength needed to crush the can. Although I do see some downsides you listed as things to address and consider.
on the issue of small dc motors i am talking about small hobby motors used in cheap kids toys with often plastic parts while i’m sure i could get a decent amount of torque from these i doubt the they would remain functional with enough resistance i’m concerned more with the motor becoming the weakest link in the system and i don’t know of anyway to reduce the pressure that the motor will experience. Any ideas?
As for scavenging, I had not thought about a treadmills motor, interesting idea. My father services and repairs dog dryers and clippers so we have some largish brushed motors around mostly for air, could these possibly be modified to provide torque or are motors designed for dryers designed differently e.g. can they not take resistance to well.
And finally the sorting mechanism i am planning to use magnets to redirect steel cans from the system and for height using a little lever to retract a trap door, its hard to explain and i cannot currently produce i diagram, when it is finished i will upload some vids of it in action.
Once again thanks for your reply.
Kinder regards,
Hunter Townsend
I very much like the idea of using magnets as a passive sorting mechanism, fewer points of failure is always best and that seems like a perfect solution. And I definitely agree with you in regards to the motor. Looking at a number of dog dryers and the DC motors inside if they were correctly geared down I reckon you’ll be in the gold.
Regardless of whether it’s moving a treadmill, pushing/pulling air through a system or wheels on an electric car the DC motors enacting work on a system always undergo a load causing stress and strain. So the DC motors in your dryers would’ve been selected based on its outputs and dimensions, but there wouldn’t be any other major design difference compared to other DC motors.
I’m keen to see the crusher in action! I hope this has been helpful and definitely keep me posted as the project develops.
Kind regards,
Tim Givney
(Also garage door mechanisms have great motors in them which could be retrofitted in a can crushing mechanism)
