Looking at some used motors. Are the motors in the links below a viable option for the shredder?
Hi, im currently in Spain starting to make the Shredder but the most expensive part is the motor, does anyone have a cheap supplier in Spain or Europe that could send the motor?
Dave do you know if the supplier where you got yours could send it? could you give us the contact?
If anyone in Spain is making the shredder im willing to help, I already found some suppliers for the other parts.
Thanks in advance
Hey Guys, I to am looking at alternative motors as-well, as the one thats recommended is not easy to find in a lot of countries.
I should say these are just some of my thoughts, as I any not a electrician, but I did have a really good talk to a mate of mine who is.
First, as already mentioned by @paulfreed over here
most households are on 1ph power not 3hp, you can run a 3ph motor at home, but you would need to use a type of inverter. The other thing that I’m finding is most of the motors that are easy to find the RPM start at 1400rpm & goes up from there.
I myself am trying to keep things simple & in turn that should keep the cost down, hehehe
So! for me I’m looking at as a alternative, is 1ph motors with as low as rpm as I can get & using in conjunction with some type gearbox/worm gearbox, so I end up with the rpm/torque that I want.
What & Places I’m look at.
Ebay, Gumtree, 2nd hand places, kerbside pickups.
1. 2nd hand drill press, some are 1400 rpm & 12 speed they uses belts & pulleys to change the rpm, (which could be repurposed to use in your design)
2. Washing machine motor
There is also the 12v & 24v options as well that I’m looking into.
I’ll share what I come across as I find it & hope others do the same.
Also, if any one know of a good online calculator that easily works out the gear ratio you need when you want to reduce the rpm of the motor you have available, to the rpm you want. That would be awesome & very helpfully all like me that are maths deficient.
@enviro thanks for merging the topics!
I’ve also thought about the drill press, but id like to avoid the cumbersome pulleys. Although its probably alot cheaper than the worm gear.
I’ve been thinking of winch and hoist motors – they have plenty of power. What do you guys think?
The winches are normally 12v used on pickups etc., but would then need additional expensive power supplies.
The hoists I favor because they have a gear on them and are 1ph. Also the gear comes directly off the motor shaft unlike most winches. I think the ones you get here are up to 1700W, just need t find a second hand one…
Here is another type of winch that’s used on 4wd’s 12v http://pages.ebay.com/link/?nav=item.view&id=262359888466&alt=web
You could pick one up 2nd hand
There is also second hand mobility scooters motors that come to mind, 24v
yes, those winches look good, i’m just worried about the current they draw. Some of them can go up to 150A which is no problem for a car battery for short periods of time, but i think for longer times you would need a power supply which then becomes very expensive again for that current rating. I think.
I dont know the specs of those hoists yet, they just say how many kg they can lift. The 1700w hoist can lift 500kg straight. Anyone know how many NM that would be?
I think you may run into problems with the Ebay one(DAYTON AC Gearmotor 70 rpm). The RPMs are fine, but the torque may not be enough. With @enviro s links I calculated Dave Hakkens’s 2kw motor at 70rpm to have 272Nm. Could that be correct?
Another Idea I just thought of:- concrete mixer motors. The ones that don’t use pulleys all have a gear system attached. Not sure of the speeds though, 20rpm may be too slow, what do you guys think?
In my opinion the best motor for this applications is the classic asyncronous 3ph motor. With capacitor properly connected you can run it with 1ph power supply no needing inverter or any other devilry.
The price of 2Kw brand new motor without gearbox starts from 150Euro, but this kind of motor is quite easy to find used in scrapyard or ebay at low price, often with gearbox mounted.
Changing form 3ph to 1ph adding capacitor, the motor loses a lot of its starting torque, but in shredder application it’s enough start the motor with no plastic inside the hopper.
do you think this motor has enough torque for the shredder?
greetings from Portugal
Hi, I found a old Car winch with the specifications of 1000 W and 600 kg and another with 900W/ 1.2Hp Motor, they are 12v but i was thinking of using a converter from 220v to 12v.
Do you think something like this could work? or i need more power for the shedder?
No, your maths is correct. 270Nm is what a 2kW 70rpm motor would produce, but it’s probably way in excess of what the shredder actually needs, and possibly also more than the gearbox can cope with, so if you were to lock the shaft it may destroy itself.
Nobody has yet posted any measurements but I’d estimate the shredder only needs 50-100Nm to chew through most things. This gives you more flexibility in motor choice, most important is the torque, then the speed, less than 70rpm is probably fine, it will just go slower, too fast and material will get thrown out instead of shredded. The torque x the speed tells you the power of the motor you need to look for.
Hi @andresfabertime the hex bar can be hard to find, I have found that out my self, in Australia it is not something standard to be found at metal merchants & when you do find someone who will get it for you, they want to sell you 3m of it, also the size here, 27mm is also not common.
So this is what I am doing.
The 2 hex bar sizes in my country that are more common are 28.5mm & 25.4mm, it just so happens that crowbars (that’s what there called here) are 25.4mm & you can find them at scrap metal yards easy. Here is a photo of one.
Note: you will need to change the CAD file to allowed for the different hex size.
Hope that helps 🙂
Hey, @plasticona yea i also think the winch would do but im not sure about the strength of the motor is enough.
In case of the axe, @plasticona and @enviro i found only one place until now that you send the bluprint or the 3d model and they send you the piece, the web page is this one http://www.protoandgo.com, I think they are in Barcelona but for me is expensive.
@enviro the 27 mm I found a company here in Madrid with those specification, but they sell only 3mts bar and to companies not to particulars, im trying to find something cheaper.
If i found something else i let you know.
Considering comment above from @andyn regarding motor torque estimate of 50 – 100nm I found this Single Phase 0.55kW 0.75HP 70rpm Electric Motor and Worm Gearbox on ebay
I tend agree that the motor in the specifications seems overated.
Using the following equation thats 75nm
Torque in SI units can be estimated as
T = PW 9.549 / n
T = torque (Nm)
PW = power (watts)
n = revolution per minute (rpm)
Single phase which is better for most application other than industrial where 3 phase supply is available
Half the price of specified motors on eBay
Hey guys, I’ve created a google docs, (Almost) definitive guide on motors, summing up a lot of the info found in your posts.
Please give it a read and tell me if I got something wrong.
the aim is to develop a cheatsheet and guide on the motors to add to the official precious plastics documentation.
@davehakkens has done a monumental work, let’s help him and us clarify better the parts on motors.
I’ve also created a forum post (yes sorry another one 🙂 ) where we can discuss motors, the document and other related stuff
I’ve also found an online Gear Generator that makes it one step easier to build our own gear reducer to convert the engine of a washing machine into something usable for the precious plastics machine
If anyone here has made the machines and they are working, please post images of the nameplate of your motor and what the pros and cons you see in them
let me know what you think.
thank you all
This might be a bit late, but I recommend against getting a crow bar or pry-bar to use as the axle.
I did the same thing, but as you are no doubt aware, the axle needs to be milled at each end down to 20mm to fit into the bearings. So I took the Pry bar down to an engineering company in town to get a quote on the milling.
It turns out that because the metal in the Pry bar is hardened, the cost of getting it milled is about twice the cost of them making an axle themselves because they will go through a heap more tools to mill it. FYI, mine cost $150 + gst but I got an extra modification which added to the cost.
Can anyone tell me if this motor would work. I think it will have enough torque but im kinda lost.
AC Gearmotor 115 Nameplate RPM 6 Max. Torque 600.0 in.-lb. Enclosure ODP
In Australia, it is difficult to get second hand single phase motors at a reasonable price. After much trawling around secondhand goods, and the internet, I decided to enter an auction for a 3 phase motor. I decided that AUD40 would be my limit. Then after a few attempts, I did get my 1.2kW 3 phase motor. I belong to a men’s shed (for retired gentlemen) and we have 3 phase power. It is a 4 pole motor, that means it will run at about 1400 rpm. I also bought a new 20:1 reduction gearbox from Ebay, for about AUD80. After some machining I have the motor connected to the gearbox. The same single phase motors are well over AUD100 (second hand), then you might as well spend an extra AUD70 – 80, and get a new motor. (also must be 4 pole, so it will spin slower, as the 2 pole are about 2800 rpm)
Hi, I have just purchased that exact hoist and I have come to the part I must remove the spool from the shaft. I saw someone on YouTube just took a rubber mallet and tapped it off, but I can see that it isn’t possible if hit it pretty hard and not budging.. do you have experience with this type of hoist and removed the spool? Did you have to open the gearbox to remove it or can it be smacked off with a rubber mallet as this guy does in this YouTube clip?
https://youtu.be/NL-k8kJ8yig 4 min mark
thanks if you can shed any light..
Looks like @patrick-bonsen used a similar configuration, perhaps he can comment on getting the spool off. Otherwise, perhaps you can borrow a gear puller or make an equivalent with a bar with a tapped hole on the center that you can then clamp onto the flange of the spool. A little heat on the spool core may help as well.
Hi, I used this motor.
This winch motor is so powerful that it bent my Shredder axis coupling when I tried to shred 6mm thick PMMA plates 🙁
The spool from the powerful 1800W (500/1000kg Version) motor is stacked on to an 27mm hex bar. you can easily pull it off.
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