It is recommended to print with filament from plastic bottles?
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If you can turn it in to a 1.75mm diameter filament, sure. Itās PET or something like that.
If you mean, using a tool that turns a water bottle in to a long thin strip of plastic to feed in to the printer, no.
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Well. It is practically āfreeā filament but when you thing of the weight of a plastic bottle (only a couple of grams) that would mean that per bottle you only get 7 or 8 grams of filament, so unless you are doing it on a massive scale, I wouldnāt say it is worth it.
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Probaly not lol , might give you nozel cloggs!
I gave it a dry a few years ago in order to utilise these nice fluoro green bottles of a certain soft drink most people might nowā¦
Only did it because I was able to borrow a filament extruder of sorts from a friend who needed me to fix it after it dropped off the table.
Was some contraption from China running on a little Arduino but worked surprisingly well once I got all straight and running again.
Collected about 150 of these green bottles through various sources over a long time and was literally hoping to one being able to do more than bindings with themā¦
Ok, how did it go ?
Easier than what I thought possible LOL
Cut the bottom off the CLEANED bottle, place it into the holder and add the weight on top of the bottle, spin it by hand to get the plastic string going and pull until you get enough to feed into the transport wheels.
These pull the plastic off the bottle and push into like a folding ramp right in front of the heater.
Once out and you got enough to get it onto the roller to spool up you lock it in and let the machine do its thing.
As far as I worked it out the spool mechanism provides a constant pull on the extruded plastic - a gentle pull that results in getting the more or less accurate diameter.
The 'filament came out with distinct line visible along it but is was just visible you couldnāt feel it - like the lines on the first layer on a smooth build plate.
Performance of the filament ?
Wellā¦
I tried drying the bottles prior to cutting them, tried drying the resulting filament and any combination possibleā¦
The prints were acceptable at best but nowhere near what you get out of a PETG filament for printing use.
The inconsistencies are probably not as much the result of how the home made filament was made but how the bottle was made.
These soft drink bottles start as surprisingly small dummies.
Only the screw top part stays the same.
A machine holds and seals the top while the mould closes and the extra hot steam is used to blow mould the bottle - fast, efficient, working well for THAT purpose.
The PETG blend used is created for this type of manufacturing, allowing the PETG to stretch well past the usual physical limitations EVENLY.
Means you already have to fight against two enemies here.
First the fact that the PETG from your bottle shrinks once heated up.
Secondly that the polymer chains are already damaged past the rejuvenating stage.
Like a rubber band you left stretched to the max for a few days outside in the sun the plastic just wonāt fully recover.
So once printed it can shrink even further and this rather unevenly depending from which part of the bottle it came, a thinner or thicker sectionā¦
No to mention that whatever additives and such are used probably wonāt tolerate the much longer time in the melting chamber during printing giving you result not always easy to understand as the only reference we have is dedicated filament for printing useā¦
There is now new filament extruders claiming to be able to address and fix all these issues.
They seem to sell surprisingly well tooā¦
Especially in countries where printing filament is hard to find or too expensive to consider.
We can eve see comeback of 3mm solutions as the larger diameter makes things a lot easier in terms of recycling and being able to use filament extruders with a feed screw rather than just heating the string to binding temp and pulling it through the extruder.
For us ānormalā people with access to affordable filament the investment and hassles are just not worth it.
A half decent filament extruder sets you back a few hundred bucks and requires constant care and monitoring when in use.
Add the costs for electricity and consumables and you really need a lot of bottles to justify the investment.
Only to still struggle with consistent results you can replicateā¦
If you cater for resort, club or whatever and have unlimited supplies of PETG bottle go for it, otherwise you might find that getting these bottles to a recycling machine to get the few cents back from it might pay for the real PETG filament as well 
Around here we get 10 cents per bottle when dumped into the recycling machine.
A roll of PETG delivered as a set of 5 or 10 comes at around 20 bucks, sometimes lower.
200 bottles to get one roll.
How many bottles do you need to extrude one kg of filament ?
The well known 1.25 litre bottle of the dark brown soft drink clocks the scale between 30 and 40g.
We can only use the the middle section but not the bottom or the thick top part, reducing the available bottle to 20g or LESS.
Letās go with 20 to have it easy, means you need at least 50 bottles to make a full 1kg roll, more like 25 as you have to keep joining those strips.
Have it all honed in and ready to roll and you can do a full roll in about 4 hours, maybe a bit less if all goes well.
With unlimited supplies of bottles the recycling containers turns into money I would still take 200 bottles down there and order a roll
3D printer filament has all sorts of additives to help it melt and flow and recrystallize when it cools. The base stock might be the same as whatās in a plastic drink bottle, but the actual filament wonāt be nearly the same for lack of all those fancy (and in some cases proprietary) additives.
In addition, itās actually pretty hard to extrude printer filament and control the diameter of what gets extruded. The diameter is going to depend on the nozzle size, but also the temperature and pressure being used, and how much tension is on the take up reel. Any variations in temperature and pressure and take up tension will change the diameter of the filament.
I suspect āhome madeā filament is going to print sub-optimally because diameter isnāt tightly controlled, more than that it is missing additives.
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Ive seen a breakdown of the kickstarter, it appears, at least atm that not much has been done with the hardware , videos, site everything is very well put together but Ive yet to watch one in action, if this is indeed the filament maker Ive seen reviewed