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Share your Shredder motor experience

This topic contains 77 replies, has 24 voices, and was last updated by  Anonymous 7 months ago.

9
Olivier xxxolivierxxx

Share your Shredder motor experience

16/11/2017 at 03:35

Hello Everyone
Many people around the forum has seen @lyricalpolymath ‘s “almost definitive guide on motors” and I’m sure many of you found the information collected on that topic useful on the initial stage of your Shredder build project.

My intention on this topic is to collect information about success/failure stories with the motors you tested on your shredder, along with specs about the motor you tested.

For instance, I read that @seyn-sustainableenergyyouthnetwork tried a monophasic 3HP motor on the shredder and it clogged very often. @lyricalpolymath also reported that monophasic motors are not good enough for the shredder regardless of their HP.
My aim is to collect a concise database of real-life machine builder stories about their experience building the shredder and which motors they used.

I’ll start:

#######################################################################
Owner: @xxxolivierxxx
Motor type: Monophasic
Voltage: 110v/220v
RPM: 1430/1710
Reducer: 1:30~
Output RPM: 56/60
Power: 1/2HP
Result: Failure
Details: The motor is simply not strong enough to shred any type of plastic. I even added a reverse switch to see if that would help but it was just a waste of time/money.
Here’s a topic I made about my Shredder: https://davehakkens.nl/community/forums/topic/my-shredder/
#######################################################################
Owner: @flo-2
Motor type: Monophasic
Voltage: 230v
RPM: 1400 rpm
Reducer: 1:25
Output RPM: 56
Power: 2.2kW
Result: Success
Details: Weakest point is the coupling, turns freely when load is too much. I have got around 280Nm and thats enough for most things to shred. Only very thick industrial plastic crates create problems.
#######################################################################
Owner: @baas
Motor type: triphase
Voltage: 230v – 400v
RPM: 2280
Power: 2.2kW (+- 2,5 HP)
Reducer: 1:49
Output RPM: 46.5
Result: Success.
Details: I was lucky enough that a friend gave me a relais etc for free to convert the triphase motor to 230v without loosing power. But its expansive.
Also i added a thick heavy hex coupling with keyways. It looks way too big but according to the formula its needed.
Its really strong. It only clogs shortly when the shredderbox is filled with plastic particles.
Watch Ed shredding here ;D

#######################################################################
Owner: @kettlekekkers
Motor type: mono-phase
Voltage: 230/40v AC
RPM: about 2500
Power: 2.8kw
Reducer: inline planetary/comes with motor
Output RPM:45’ish
Output N.m; 500’ish
Result: Success. very good
Details: cheap and easy to use and apply to assembly.
shreds up to 3mm thick PP or HDPE as far as I’ve tested, compressed milk cartons could be considered more like 5/6mm thick.
electronics easy to understand and reassemble
when clogging occurs, its easy to revers with the already provided switch.
Disadvantages: its very loud! and has a 36.5mm shaft output , no choice.
#######################################################################
Owner: anne-barbier

Type: 3 phase
Voltage: 230v
RPM: 1440 rpm
Reducer: 1:20 , SITI – Service Class 1
Output RPM: 72
Power: 4kW
Inverter: 4kw
Quality: Low, I assume a proper ABB motor can do magic here
Result: fail EDIT: After grinding the shredder blades to a 30° cutting angle, the result is a success (read further on this thread for more details)

Video: https://www.youtube.com/watch?v=4SNiDleTKac
#######################################################################

Owner: @stoli
Motor type: single phase
Voltage: 220HP: 3 (2.4 @80%)
RPM: 1740
Reducer: Worm gear 60:1
RPM:29
Output calculations based on 80% motor and 75% Gearbox :325 Ft/Lbs (440 NM)
Result: Success
Details: Good RPM, very strong. Rarely needs to reverse.Built with (2) 4″ pulleys power to drive train so the belt can slip to save the mechanics if it does bind. Flakes in picture is using a 5mm hole sieve.

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helper
28/06/2018 at 06:34
4

Owner: stoli
Motor type: single phase
Voltage: 220
HP: 3 (2.4 @80%)
RPM: 1740
Reducer: Worm gear 60:1
RPM:29
Output calculations based on 80% motor and 75% Gearbox :
325 Ft/Lbs (440 NM)
Result: Success

Details: Good RPM, very strong. Rarely needs to reverse.
Built with (2) 4″ pulleys power to drive train so the belt can slip to save the mechanics if it does bind. Flakes in picture is using a 5mm hole sieve.

Attachments:
helper
17/11/2017 at 18:16
4

Owner: @baas
Motor type: triphase
Voltage: 230v – 400v
RPM: 2280
Power: 2.2kW (+- 2,5 HP)
Reducer: 1:49
Result: Succes.
Details: I was lucky enough that a friend gave me a relais etc for free to convert the triphase motor to 230v without loosing power. But its expansive.
Also i added a thick heavy hex coupling with keyways. It looks way too big but according to the formula its needed.
Its really strong. It only clogs shortly when the shredderbox is filled with plastic particles.

watch Ed shredding here;D

starter
05/07/2018 at 06:51
3

Guys. This is not correct regarding capacitors and motor sizing. Go to Grizzly.com and other websites. They sell static phase converters up to 10hp and rotary phase converters up to 75 hp. The reason you don’t see/use capacitors over 5hp is because rotary is more economical using smaller capacitors to create the third phase. I used a 15hp rotary for 5 years for a yag laser engraving machine. No problems. A VFD is basically a bunch of electronic controlled capacitors. You can “create” your own phase converter” as long as all output phases are within 5% (exact same is best but nearly impossible) of one another and 10% of nominal voltage it should work just fine. Please educate yourselves. There is a lot of info on the internet regarding rotary phase converters. Best of luck to all.
PS. Currently I’m using 220v single phase 15.3 amp input VFD and getting 220v 3 phase 7.0 amp output. it’s still just capacitors only!

new
25/06/2018 at 21:30
3

guys, i’ve made another fine tune on the blade tip, i gave the blade tip a 30 degree cutting edge and now it’s cutting like all like butter, the ampo-meter on the inverter shows a 40% drop for the amp peaks compared to before, also way less vibration coming on hard plastic, so it’s cutting at an average of 8 amps now (not sure it’s right but the peak drops are significant). i guess i weld it together now 🙂 what a fecking ride, 3 full days to get here. always good to question EVERYTHING at the end 🙂
g

dedicated
22/06/2018 at 23:54
3

@olivier, this 200 Nm will work perfectly with the filaMaker I will use for built next shredder machine, the final sell cost is quite the same of de PP shredder, due to the cost of the motor, the easyer frame and the lower shipping cost, in add the electricity running cost are minimum 1/3 of the PP shredder, in country where the electricity is expensive this make a lot of difference.
I think in the forum we will put a similar post with the really needed power of the machines, when I read post where people says they usa a 5Hp motor to run the shredder, I feel bad, electricity is no 100% produce from renewable sources so we are fighting plastic pollution but we will create other kind of pollution.

Attachments:
warrior
12/12/2017 at 21:24
3

I’ve developed an Excel calculator based on peoples experiences in this thread, you enter the motor and gearbox parameters and it tells you well it should work, please see this thread.

helper
27/11/2017 at 20:14
3

@tinch

its a good question , i think it needs examplafying to make it easier to understand how gearing and torque work with RPMs and horse power, somehow..

but in essence yes , gearing it down massively would work bit, however really slow speed means it will take longer to process plastic then cutting it with scissors…
don’t know if you have ever come across an art work by Arthur Ganson, called “machine with concrete” its geared down so much that the output will take a trillion years to do ONE rotation, i bet it has silly amounts of potential torque though…haha

starter
19/11/2017 at 22:18
3

Completely new, didnt read everything

I am currently building a Universal Motor Controller, so I can reuse old Washing Mashine Motors. Will share and translate what i collected.

PRO: Easy to get (i only paid gas for my car to collect the WM’s), simple to recycle aka getting it out of a washing mashine, recycling another component

CON: They need a speed Controller, otherwise they get faster and die.

Will edit and film my progress, may be able to sell the Motor Controler Boards with solder-ready components 🙂

helper
19/11/2017 at 15:19
3

@andyn its only jammed a few times when i put 3 milk cartons together, which is kinda unnecessary,
or when i tried a thick Polypropylene jerry can pieces, which are about 4mm thick on the some parts,

the jaws have the original grub screws tightened agains a flat on the shaft, the bolts are just to keep them tight because they kept loosening, as i didn’t want to use lock tight glue,

helper
18/11/2017 at 22:39
3

Owner: kettlekekkers
Motor type: mono-phase
Voltage: 230/40v AC
RPM: about 2500
Power: 2.8kw
Reducer: inline planetary/comes with motor
Output RPM:45’ish
output Nu; 500’ish
Result: Success. very good

Details: cheap and easy to use and apply to assembly.
shreds up to 3mm thick PP or HDPE as far as I’ve tested, compressed milk cartons could be considered more like 5/6mm thick.
electronics easy to understand and reassemble
when clogging occurs, its easy to revers with the already provided switch.
,
..
disadvantages’ : its very loud! and has a 36.5mm shaft output , no choice.

My shredder and its costs

warrior
18/11/2017 at 00:55
3

@andyn Makes sense, (375/100)*75 = 280

@jojojays, you will probably be interested on reading this thread

new
17/11/2017 at 15:19
3

Shredder weight

I’ve found a 2,5kW gearmotor weighing at 60Kg, it puts out 356Nm at 68rpm
what a beast!

might be a bit of an overkill, BUT, i think it would be a good investment for future upgrades.

https://planetcalc.com/1908/

I can foresee that the total Net weight of the setup will be in the 80Kg range. kind of worried about that. wish me luck

warrior
17/11/2017 at 07:55
3

Thank you @flo-2
When you say that it turns freely, does it mean you didn’t add a key/keyway on your shaft?

warrior
17/11/2017 at 07:48
3

@xxxolivierxxx 2.2kW 1400 rpm, reducer 1:25, output 56rpm. Weakest point is the coupling, turns freely when load is too much. I have got around 280Nm and thats enough for most things to shred. Only very thick industrial plastic crates create problems.

yours
Flo

warrior
16/11/2017 at 21:13
3

He said their shredder had a 50:1 ratio but didn’t say how many RPMs the motor had. Assuming that their motor was around 1800rpm then it should have been reduced to 36rpm

warrior
16/11/2017 at 13:59
3

Hey @xxxolivierxxx, didn’t you since build a better shredder? Power:2HP rpm:??? result:???

It would be useful to have as many reference points as possible. The ‘standard’ PP shredder: 2kW, 70 rpm, result: unstoppable.

It’s not just about the motor (and whether it’s single or 3 phase). The choice of gearbox is very important too. 70rpm is not ideal for every motor.

warrior
26/07/2018 at 07:54
2

@halimwidyakusuma a double shaft shredder should be capable or shredding using a less powerful motor but theoretically the output should be slower because of the smaller teeth (assuming we are talking of same-size shredders). Precious Plastic only has a single shaft shredder so we can’t speak on regards of other shredder designs, but there are plently of videos on youtube that you can use to compare both shredder designs

starter
19/07/2018 at 02:23
2

As recommended by Güenter ( @anne-barbier ), the cutting edge from my blades have been changed from a straight 90° to a 60-50° through out the edge of both sides as shown in the photo.

A couple of photos w/ the final result as well as a video showing how I did can be found on the following links:

http://www.instagram.com/preciousplasticmexico

http://www.facebook.com/PreciousPlasticMex

Attachments:
dedicated
05/07/2018 at 22:51
2

@sheffieldcompany thanks so much for the explanations, it’s always good to see real competence bind to the cause.

starter
05/07/2018 at 21:40
2

@xxxolivierxxx. Yes VFDs are quite versatile for regulating speed easily and braking a motor from 3200rpm to zero rpm in 2 seconds etc. I don’t think you really need a VFD for shredding. Just reversing capabilities and even that is not needed. Just unplug the unit and rotate it by hand backwards. Shredding is a complete science. There are several companies that only focus on that. To think the shredder will never jam is not realistic. Vecoplan, Rapid granulator and others only focus on shredding. Neither of their websites guarantees no jamming. I really suggest everyone focus on the capabilities to shred not the speed of completing the activity. You still need to make something and shredded plastic is not really a thing.

starter
05/07/2018 at 21:31
2

Hello All. Here is the most clearly defined way of describing phase converters.
Static phase converters are a startup device for three phase motors on single phase power.

Static phase converters operate the three phase motor they are connected to on single phase. The static phase converter does not actually generate three phase power continuously as a does a rotary phase converter, but only long enough for the motor to start up. Once the three phase motor has started up the static phase converter circuitry disconnects itself and the motor continues to run on single-phase power but because only two of three windings receive power during running, horsepower output is reduced down to between two-thirds and one-half the rated motor horse power. A 15 HP motor will start with the power of a 15 but run as a 7.5 for example.

The high starting torque with reduced running power is an important factor when considering the use of a static phase converter. In some situations this can work out very well but the static converter does have limitations. Static phase converters are not well suited for machines that operate continuously close to the maximum rated horsepower of the motor that operates them. This type of continuous full power loading can be seen in equipment such as water pumps. The pump is sized to use all of the motor’s power while pumping. Lathes are another good example of this need for full power. Although the static phase converter appears to work well on lathes in the slower speeds, in the higher speeds the converter is able to start the lathe turning but the lack of rated horsepower makes these higher speed settings useless. A TEMCO Rotary Phase Converter is best suited for this application.
Taken from http://www.phaseconverter.com/what-is-static.html
Now study up and then move forward!

new
24/06/2018 at 19:31
2

@xxxoliverxxx, i had another run with a different cutting edge design, i used similar angles & clearances as recommend for any other cutting tools. no more jamming 🙂

Dave’s initial design of using straight 90 degree cutting edge is too aggressive, if you give it a 10-15 degree twist, it’s cutting like butter, no idea for how long 🙂

i guess i will have to grind or machine a 15 degree taper around the whole blades.

please update: RESULT : success

dedicated
24/06/2018 at 18:40
2

OMG this is really top-notch-amateur-style. You are not even capable to built the shredder with a video-guide? And you dare to give lessons to the whole community? At least, now, we all know on which level your “skills” are. I am speaking of your claimed 20 years experience in machine building, dozens of cnc’s constructed and all that.

dedicated
22/06/2018 at 23:44
2

This is a list of monophase motor with the resultant torque, the data must be lower about 10% due to the reducer efficiency but he give us an idea of which motor can work.
As you can see is no sense use a 2.2 kw motor with 70 rpm, i think we must think in how can be sustainable this project and the first thing is the efficiency.

Attachments:
starter
27/12/2017 at 16:31
2

I used a 5HP 3-phase motor with a VFD running single phase (220V 2-wire), so 2 leads on the input side of the VFD, 3 leads on the output side. 1800 RPM

Gearbox was a worldwide electric inline reducer: http://www.worldwideelectric.net/product-category/gear-reducers/inline-helical-gear-reducers/

First one was a 20:1, 76 RPM gearbox. This didn’t have enough torque for my shredder (larger than this) design, and moved very fast so if it jammed it was violent.

I then upsized to a 60:1 (28 RPM), this has plenty of power but my shaft was undersized, it sheared the keyway.

The coupling I ended up with is a chain coupling. https://www.mcmaster.com/#standard-shaft-couplings/=1av78pa

These work really well because it’s easy to adapt different size shafts together, they can handle some misalignment, are easy to assembly, and they’re pretty cost effective.

dedicated
29/11/2017 at 13:03
2

torque range What I can tell from all the people I have spoken to is 70rpms kicks the plastic out a bit and 56 rpms cuts quite nicely but takes a bit too long so what torque what you need for a sweet spot of about 62 rpm ? how do you do the calculation

helper
27/11/2017 at 16:18
2

thanks for all the information!
so, according to what @flo-2 shared, 280 Nm should be enough to shred mostly any type of plastic. but i have a question about that, because you have many ways to get similar values of Nm torque. for example, a 1hp motor with 20 rpm of output speed or a 2hp motor with 40 rpm should get +-356 Nm of torque.
so the question if it´s really the same because of the torque, or does the other factors make some differences on the behaviour of the shredder.
i don’t want to fail on buying the wrong or not enough strong motor because they are not so cheap in here.

warrior
27/11/2017 at 07:45
2

@kettlekekkers thanks for your input, added to the main topic

@pixeldieb washing machine motors have only about 0.3HP, and using a pwm to control the motor speed will reduce the torque even more. Just wanted to mention that so that you keep it into consideration 😉

warrior
17/11/2017 at 22:30
2

@baas thanks a lot for your reply.

@andyn if I use this page to calculate the torque of @flo-2‘s shredder, I get 375.13 N.m which is a lot of power but not quite close to the 280 N.m reported by Flo. Not sure if there are any details I’m leaving behind in the formula appart from the power and RPM

warrior
17/11/2017 at 18:26
2

@andyn The motor company where i bought it calculated the torque for me, so it should be correct 🙂

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