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V4 PET solutions – [ROPES & FILAMENTS]

This topic contains 11 replies, has 5 voices, and was last updated by  Yann 2 years ago.

Yann lagrenouille

V4 PET solutions – [ROPES & FILAMENTS]

06/11/2018 at 13:05

Hi guys !

Yann here, I already posted on “Finding a solution for PET” topic, but as the rope making takes a lot of experiement by itself, we decided to create a separate topic. So this part is a copy/paste from last one, and I will a some new imformation shortly !

First there is some parameters that are mandatory during the process :
– Keep equal tension in all fibers / yarns
– Equal rotation speed for all yarns
– Perfectly free rotation at the end of the rope
– Keep rotating all yarns while the strand start to appear but at lower speed
– Maintain reasonable pressure on the separator

Here are some parameters that have influences on the rope quality and that we had tested / will test :
– Bottle strip width and regularity
– Untouched strip or “pre-rotated” strip stabilised in this form with an air heater
– Flat bottle or grooved bottle (influence on regularity)
– Same bottle type or mixed bottle supply (influence on regularity)
– Fiber joining (knots, torsion…)
– Tension (at the end of the rope, by the rotation tour number…)
– Rope type : quantity of fibers per yarn, quantity of yarns per strand, quantity of strand per rope (currently making a 2 filaments per yard / 3 yarns per strand / single strand rope, a filament is corresponding to one bottle strip).

Some conclusion have already been found :
– Pre-rotating and heating the strip makes it look smoother and gives it a better reaction to torsion : the strip resistance being more homogeneous.
– The smaller the strip are, the better the rope appearance and smoothness is.
– There is no need to pre-rotate small strip (up to 3mm), but it is mandatory for bigger one to maintain a good appearance and a proper torsion reaction during the making.
– It is also mandatory to pre-rotate irregular strips for the same torsion reaction (risk of breaking in weaker spot before obtaining the right torsion).
=> Therefore the best material for rope making would be strips as small as possible, supplied from the same ungrooved bottle type.

And eventually we will continue working on the following point :
– finding the best cutting method to obtain small and regulare strip + automatised process
– if possible this cutting method works also on disparate and grooved bottles– finding a better connection method than knots
– when the process is mastered, experimenting on various filaments/yarns/strands quantity

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08/11/2018 at 12:45

A little bit more information on how the ropes are done.

First GIF :
Frist of all you must obtain some strip out of a PET bottle. As said on the post above, the thiner the strip is the better outcome you will get. Also using ungrooved bottle simplify the process. Out current cutting maching is a cutter blade placed on top of a calibrated cut on a metal beam. The depth cut shall be the strip width you want to obtain, and the cut shall be as thin as possible for the strip not to tilt during cutting. The bottle is maintained to the right angle with a metal guide.
We added a system that allow us to spool the strip autimatically in order to save time.
Further improvment have to be done on this machine :
– Better rigidity
– Easier and faster spool set up
– Better guiding system (this one is difficult to set up)
– Add a system to transform the flat strip into round filament
– Add a system for bottle preparation before strip cutting

Second and third GIF :
Then you can process a rope. Still with a drilling machine and a belt, three pins are rotating together. Then on the other side, the tention is maintained with a weight, but with free rotation possibility. You have to maintain your yarns separated until you get a satifying torsion in all yarns. Then the yarns are automatically turning arround themself making the rope.
You can vary the rope size by adding more filament, by using pre-made small rope to obtain a bigger one etc… Rope lenght is theorically unlimited as both system side are independent from each other.
Further improvement will also be done on this machine :
– Independant set up (instead of using a table)
– More versatility (more possibility in number of yarn & strand)
– Possibility to count rotation number (important rope caracterisation number : higher rotation number means denser rope, and denser rope means more tensilte resistant rope, but up to a certain limit, to dertermine for PET)

08/11/2018 at 12:53

yeahh gifs! 👊

11/11/2018 at 15:33

As I have some questions from time to time about what we would use the rope for. Basically everything you would use a normal rope !

Here some application already under testing : hanging clothes, lacet, bike luggage rack attachment, dog leash.

Also, we can use the strip directly to make various construction. Here an example on attaching a paddle on a wood handle. You can use the retraction propertie of PET to normally knot anything with a strip then heat it to really tight the attachment.

More example wil follow depending on our moment inspiration or needs. Some ideas that come to me immediatly :
– Stool woven seat
– Swing
– Boat mooring…
Do not hesitate to give us ideas !!

18/11/2018 at 01:43

I’ve seen some cool things folks have done like:
https://goo.gl/images/gY99CR   that’s a thin copper strip threaded through wood like a shoelace.

Of course you could do something like knife or tool handle wraps:  https://www.wikihow.com/Wrap-Paracord-Around-a-Knife-Handle

Or maybe seat weaving like:

Here’s someone who started doing a pretty decent looking hammock but gave up when he saw how long it took to make the rope.


I think a big thing is to just have some available to you all the time.  Start thinking of how you could use it.  Distinct colors will let you make things more interesting.  How can you play with strength and texture? What’s it feel like in your hand?  Would you want a few weaved together before you’d use it for a big lift?  If a big dog gave you a big dog tug on it how would your hand fare.  If it’s rough it’s not necessarily a bad thing.  Maybe some sort of hand wrap or scrubby type thing like a louffa could be worked out.

One thing seems to come up is that each of these sorts of products is greatly enhanced by a familiarity with a relatively established set of skills.  Like this rope product could probably benefit from the maker knowing about knitting, knot tying, weaving, or just a little sewing.  Learning how to delicately apply heat to a wrapped object might even let you do a sort of molding with it.

29/11/2018 at 13:27

In agricoltura si usano ogni anno molti kg di plastica come teli reti e corde….
Un esempio : in un vigneto    le corde in plastica aiutano il mantenimento della forma.
Dopo la vendemmia finiscono in discarica.
Il mio suggerimento è di riutilizzare queste corde piuttosto di creare corde  da bottiglie di plastica .
🙂 sorry for my uk but ideas not have frontiers ciao

29/11/2018 at 13:35

Questi sono alcuni tipi di corde , nastri teli e tessuni che finiscono in discarica

07/12/2018 at 01:50

First ideia that came to me was a HUGE hammock like this one https://br.pinterest.com/pin/116671446570161280/
But later thinking this could be combined with the fusing plastic bags technique and make those rucksacks like this one https://br.pinterest.com/pin/469007748680570207/

07/02/2019 at 17:56

Sorry, long time not posting here, but it doesn’t mean I didn’t work on it !

I actually spend quiet a lot of time figuring out a reliable method to make strip and wire out of PET, and then design a built a first prototype. This have to be seen as a production line to obtain a base material, this material having to be used in various application, still to be experimented, afterwards In comparison, this would be the shredder equivalent for PET bottle, that you can then process for weaving, rope making, attachment…

So the first step was to obtain a reliable cutter. Previous version was built with a cutter blade, the big inconvenience was the unsharpening of the blade : the cutting always occurring on the same spot, the sharp edge disappeared very fast. So we switch to a system that actually shear the bottle instead of cutting it, by pulling it between two overlaid bearings. I will call that a ‘not to difficult to built system’ but once taken the time need to make it, it is super reliable and versatile.

07/02/2019 at 17:58


Difficulties :
– Bearings sharpening
– 0,5mm precision for bearing and guide position holes
– Welding and threading needed
– 0,5mm precision cut for spacers

Machine needed :
– Grinder with cutting disk
– Table grinder
– Drill press
– Welding machine
– Measuring and marking
– Thread makers

Steps :
– Cut a 80*100*>4mm plate then drill and thread it as indicated on the drawing (see picture),
– Cut 3*40mm M8 thread bar, then make a cut in one of them (~7mm deep, ~1-2mm wide),
– Cut 2 spacer in a pipe with 8mm internal diameter, one 10mm and one 17mm,
– Cut a 400mm 4mm rod,
– Sharpen two skateboard bearings by putting them on an axis (M8 bolt) and using a table grinder (see picture),
– Install the two M8 thread bar without the cut on the front holes, and the 4mm rod on the 4mm hole, they should brush the bottom surface,
– Weld them in space from the bottom surface, then grind it flat again,
– Install the third thread on the last M8 hole, the cut shall be on top,
– Install a spacer, a bearing and a nut (in this order) on each front M8, start by the 10mm spacer, that shall be on the 4mm axis side

Cutting steps :
– Cut bottle bottom in two steps
– One sloppy to remove the bottom
– One fine to make it flat and smooth
– Without any pre-cut, place the bottle on the vertical axis
– Place the cut edge in the guide and slide it between the bearings
– If needed, slightly pull down the bottle doing so
– Pull the created strip, the speed will depend on the bottle regularity
– Once 2/3 of the bottle cut, put a weight on top

Tricks :
The cut thread is the guide, you adjust the height by screwing or unscrewing it, every half turn will move it by ~0,5mm
Adjust the axis (4mm rod) depending on bottle diameter, it have to be slightly bend on the back and on the external
Pulling speed is the key for regular strip, play with it 😉

07/02/2019 at 18:02


Then this cutter will be integrated in a small production line to be able to process it efficiently. The bench is though to be built completely as the fist time, and complete step by step by adding the tools depending on what is wanted.

It will contain 3 modules :
– Pre-cut bottle bottom to increase production
– Strip cutting with mechanised pulling and storing
– Strip calibration to a wire with mechanised pulling and storing

This last step is also one on which I spent quiet a lot of time, but application can be endless. By heating an aluminium piece with calibrated hole, you can use the thermoreaction of the PET to give a round section of the strip by pulling it through. No fusion is involved, so PET is still very easy to process.

This small round wire can be then used as fishing wire, sowing wire or maybe even 3d printer wire with a very easy production process (It have to be tested, but I am waiting my 1,75 calibrated hole !). This would still be limited by the strip length, but you can obtain 25m of 2mm strip out of a 1,5L Coca Cola bottle 😉

07/02/2019 at 18:04


We went recently on a laboratory to be able to do some tensile test on ropes. Result are very promising as you can see on curves obtained, we have a very classical elastic material comportment.

Result can be summarized that way :
– Each 1mm strip included in a rope can hold 2,5kg, before rope definitive deformation, and at least 2 time this weight before break (sliping out of the machine before breaking) : 15kg for a 6 strip rope, 30 for a 12 strips rope, 45kg for a 18 strip rope…
– Ropes are approximatively half resistant compare to a same linear weight industrial twisted polyester rope, even if diameter of PET rope is bigger. For 11g/m : PET is 5,5mm diameter for 3,5 for a twisted polyester rope
– Elasticity is very important : 10% before definitive deformation and more than 100% before break. In comparison, a PET straight bar can hold max 36% deformation before breaking, and a twisted polyester rope break aver 20% deformation

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