sheffieldcompany

starter

05/07/2018 at 06:51

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!

xxxolivierxxx

hero

05/07/2018 at 07:37

@sheffieldcompany I’m still learning about triphase motors and how they work, but I had the same question. In theory, VFDs are the same as using capacitors but with the added benefit that you can regulate rotation speed and have a unified control system.

plastikfantastik

dedicated

05/07/2018 at 09:05

xxxolivierxxx I have been looking at youtube videos of different shredders and even the bigger ones will jam if there is too much material being put through. I watched each of the videos for this very thing and they all did it.
Thought this fact might be of interest. I think the expectation of no jamming is a bit unrealistic.
owner plastikfantastik
Motor type: single phase
Voltage: 240
RPM: 1440
Reducer: Worm gear 20:1
RPM:72
jamms a bit but ok when put into reverse it corrects easily

xxxolivierxxx

hero

05/07/2018 at 20:45

@plastikfantastik How many HP/KW does your motor have?

Mine is a 5HP 220v triphase motor converted to 220v Monophase using capacitors. If my math is correct, I should lose around 1HP in strenght. At 4HP I should have around 569.64n.m of torque which is plenty. I understand that too much plastic could jam the shredder, but I also think a better shredder design might help overcome the jamming issue. I took a jug of milk which is made of soft HDPE, and cut the gallon in 4 pieces. Adding 3 of those pieces into the shredder jams it which is a little dissapointing. I’m planning to try guenter’s suggestion of sharping the blades a little but I fear it might reduce the shredding ability

sheffieldcompany

starter

05/07/2018 at 21:31

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!

sheffieldcompany

starter

05/07/2018 at 21:40

@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.

sonik

dedicated

05/07/2018 at 22:51

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

arq-hector

starter

19/07/2018 at 02:23

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

halimwidyakusuma

dedicated

26/07/2018 at 07:03

What is the different of single shredding shaft (precious plastic design) & double shredding shaft?
Is it because saving the cost for building the shredder machine, so you build the single shredding shaft machine?
Will i get more quantity‘s plastic granulate & better quality‘s plastic granulate if i build the double shaft shredder?

xxxolivierxxx

hero

26/07/2018 at 07:54

@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

halimwidyakusuma

dedicated

02/08/2018 at 05:21

ok, thank you xxxolivierxxx. that’s explain a lot..

cristou89

starter

06/10/2018 at 15:33

Hello everyone, what would be your engine configuration powerful/torque to build a huge shredder which can treat about 50kg per hour ??
Thanks

mohammede335

helper

09/11/2018 at 22:39

hi Precious Plastic community , are its possible to make a direct coupling between motor and the shredder so its possible that the shredder turn 1500 rpm , and to shred plastic with this speed , and which is good to shred the direct coupling or   pulley and belt transmission

daverodda

new

13/11/2018 at 20:28

Hi…I’ve seen lots use a rigid coupler held on with screws on a plain shaft, this is bad for two reasons, it will slip when overloaded and the screws will tear up the shaft, and unless very accurately aligned it will cause binding.

seo specialist

xxxolivierxxx

hero

13/11/2018 at 21:41

@mohammede335 if you can only get rigid couplers then its fine, they will work, although its not recommended since you can damage your motor, reducer, or even the shredder. On regards of shredding at 1500rps, that is a really bad Idea. At that speed, the friction will cause the plastic to melt. It might work but you would need a different shredder design

mogambo

starter

22/02/2019 at 16:59

Hi! I found a cheap motor online, could you let me know if this could be fit for the shredder?

https://www.ebay.de/itm/Elektromotor-Drehstrommotor-Kompressor-Motor-Asynchronmotor-B14-0-37KW-0-18KW-/254098946752?var=

Thanks in advance guys! I am just starting and getting all the knowledge from you I can!

@mogambo: no! you need 2+ Kw and the reducer. it’s hard to find such motors on ebay. our trader wants 359e for all inkl., before tax and transport.