Replacing a hand crank with power driven motor

markie g

Distinguished Member
Joined
May 25, 2008
Messages
7,103
Reaction score
2,643
Points
1,756
I work from home and i have to dispose of a fair amount of waste i.e plastics. So i invested in a mini shredder (see attached) which helps me massively reduce the amount of waste (volume wise).

We use a similar machine to the attached but it's a hand crank which is removable. What's the best way of replacing this with an powered turning mechanism.

I guess we need some sort of power unit (going to be used indoors so no generator if possible), and a turning motor of some sort. Ideally one where I can control the turning power.

Hope this makes sense
 

Attachments

  • 13237756_845012428936486_422730627409929030_n.jpg
    13237756_845012428936486_422730627409929030_n.jpg
    84.8 KB · Views: 294
Sorry can't help - just came to suggest the title is fixed :eek:
 
Cordless electric drill? A decent one should have enough torque. You may need to get a new crank connector with a plane shank made up.
 
Cordless electric drill? A decent one should have enough torque. You may need to get a new crank connector with a plane shank made up.
I do have a fairly decent Bush driver and drill, drill is 60Nm and the driver is 160 Nm. I'd imagine i'd need at least 150Nm. So driver is probably a good shout if can get a driver connection maybe, especially with its turning action.

Can you clarify on what you mean about the crank connector with plane shank? Not really sure what you mean and how i could connect the two up.
 
Can you clarify on what you mean about the crank connector with plane shank? Not really sure what you mean and how i could connect the two up.
I guess you have a removable handle with a socket (?) where it slips onto the shredder. Lets assume its a 20mm nut. You would need to buy or make the bit that connects between this and the drill chuck. So if the shredder has a 20mm nut, then you would need a 20mm socket with an 8mm round bar sticking out the back that you grip in the chuck. It all depends what you have on the shredder when the crank is removed.

Putting my Engineers hat on.... you should really have a flexible coupler between the two, to take out any shock when the trigger is pulled. These are available off the shelf, but to be honest I think it is probably not needed and most likely a costly addition. But if you went to a local Engineering firm to get a solution, I am sure they would put a coupler in the system.

You could have some real fun with this as a project. An old motor from a washing machine or tumble drier, a belt, remote switch, timer. Depends how much you are using it. More than 2 minutes holding a drill will seem like an eternity.
 
Cordless impact wrench, used mostly in mechanics or where you need to take off tight bolts or add loads of bolts during the day.
 
— As an Amazon Associate, AVForums earns from qualifying purchases —
What grade of plastic is it? would it be simpler to just get a garden shredder?
 
Last edited:
— As an Amazon Associate, AVForums earns from qualifying purchases —
What grade of plastic is it? would it be simpler to just get a garden shredder?
Unfortunately not, it's not just plastic that goes through it, also electric and metal pieces.

I think @jonnyc is on the right tracks. I've contact the company that make it and they recommended a gearmotor l that can do 100-150NM and between 12-18rpm

Some like this:
Sew 0,25 kw 16 min gearmotor SF37 DR63L4 Gearbox

Just trying to source a UK place that sells something similar - that one is from Germany so not sure if this is electrical power or something else?
 
-- As an eBay Associate, AVForums earns from qualifying purchases --
Ok made a bit of progress with this.

I've found a suitable motor which has a 25mm shaft. However, i'm struggling to find out how to connect this to the 14mm (14mm-14.4mm will work) shaft on my shredder.

Any ideas? I believe i need a coupling but can't find any that are 25mm to 14mm?

Attached a picture of my shredder where the handle normal connects to.
 

Attachments

  • image1 (3).JPG
    image1 (3).JPG
    116.5 KB · Views: 114
What about a small pulley wheel on each and then put a belt on.
I'm guessing that would effect the amount of torque?

My biggest issue has been the amount of torque for a single phase motor. Highest i can find is about 190nm torque. A pulley system will mean even more torque is lost?
 
Belt would give you some losses. Also an amount of slip, which could be a good or bad thing, depending on how you look at it.
You could go for a chain and two sprockets. But not likely to get those off the shelf cheaply.
Belt or chain would need a substantial tensioning system too.
If you have any Engineering companies or machine shops locally it may be worth popping in to see what they can offer.
 
Cogs and a notched belt?
 
I could sell you a shredder with a correctly rated electric motor for the torque required. It'll have passed all the relevant Health and Safety tests therefore reducing the chances of you losing a limb.

How much (in weight) are you trying to shred and what particle size are you hoping to achieve?
 
Last edited:
Do you need to mount the motor next to the shredder or can you couple them directly?
 
I think he wants to couple them directly :eek: but is having problems finding a way to do so.
 
Weld them directly?
Simple idea that could work.

I'll have to check that both the shafts can be removed (in case i ever needed to replace one of either parts). But could be a solution.
 
Do you need to mount the motor next to the shredder or can you couple them directly?
Ideally wanted to mount them directly, seems the most simple solution (in theory). A few videos online of the same shredder mounted directly to a motor so it's possible.

Here's the same shredder i have online and you can see the way they have connected it. Motor is out of view but motor sits directly next to it and they are connected directly.


So does look like there's two things/connectors that have been welded together, rather than a specific fitting. Maybe the end that connects is just a deep type of socket.
 
Last edited:
Don't weld them together, you will regret it at some point in the future.
 
if both motor shaft and crank shaft have a flat spot, perhaps two short lengths of steel tube, two different sizes for each shaft, welded in the middle and then hammered slightly out of round. Drill and tap a hole on the flat spot for a bolt to secure it in place on the shaft. This way you don't damage the shaft.

Or, find a set of cogs and mount them next to each other - but you'll want some amount of play between motor and the mounting point so that it doesn't torque itself loose.
 

The latest video from AVForums

Is 4K Blu-ray Worth It?
Subscribe to our YouTube channel
Back
Top Bottom