I'm In Love With PETG

After battling with other high-temperature materials to get passable prints (Nylon, ABS) I'm watching my first attempt with PETG come out absolutely perfect. I had heard that it was worth the extra expense!

Neil

But is it sticking, does the new layer have enough welly to fuse on to the previous layer?

I am so glad we have you to lead the way. OTOH I have heard that pioneers get arrows in their backs, have a care

It stuck, PETG is notoriously sticky.

Most excellent

I have very little knowledge of matters plastic but is this related to the PET they make bottles out of?

Polyethylene terephthalate (PET) is the most commonly used plastic in the world. You can find the polymer almost everywhere you look, from your water bottle to clothing fibers, even in your food containers. PET is also used in thermoforming processes and can be combined with glass fiber to create engineering resins. Basically, thousands of consumer products, foods, and beverages are delivered and packaged within this material. Unfortunately, it‘s even floating in our oceans.

On the 3D printing side of things, there’s PETG, which is is a modified version of PET. The ‘G’ stands for “glycol-modified”, which is added to the material composition during polymerization. The result is a filament that is clearer, less brittle, and easier to use than its base form of PET.

Paul. Thank you for the excellent explanation.

V8.

One of PET's trade-names is 'Lavsan'. Ideal for 3D printing a Potty.

Shine wearing off a bit now. You have to keep fill speed down or it rips it up

Alsoi more stringy than PLA.

What settings are you using to print PETG.

It is for sale at a discounted price from one of our suppliers and I have just orderred some to try.

Edited By Paul Lousick on 06/10/2017 23:57:37

I just ordered a reel from Amazon £20.00 doesn't seem much more expensive than PLA! I too would be interested in knowing what settings are good as a starting point, this is my first venture away from PLA.

John

Edited By Journeyman on 07/10/2017 09:39:54

Well!

My woes seem to have been mostly caused by a loose hot end leaking, leading to under extrusion. It must have been the higher temperatures, caused by my experiments with nylon and ABS.

Sorted now with a new nozzle and heat break tube.

Settings:

Fill 22%

Speeds:

Travel 125

Bottom layer 35

Infill 60

Outer shell 50

Inner shell 60

Cooling fan on at 5mm z height

Minimum time/layer 5 secs

Diameter 1.73 (measured)

Flow 105%

Retraction (3.5mm) & combing enabled

Nozzle 0.4mm

Hot end 220C

Bed 60C

<edit 210C is too cool and 110% flow is too high. 220 seems to be approaching the sweet spot>

Edited By Neil Wyatt on 07/10/2017 22:07:02

Just to add, using PVA on the bed, but missed spot so the current print has a slight lift at one corner, but otherwise looks as nice as a PLA print :-/

Now up to 225 degrees.I'm finding that as I try more challenging prints it needs more heat.

Danger is too hot=too stringy, but too cool and it pulls up the previous layer and doesn't stick to it.

My temperatures are reasonably accurate, I've checked with an IR thermometer, but it was tough getting an accurate reading from the hot end, you have to be very close as it is quite a small target.

Had a first go with PETG today. Printed a 25mm test cube, first one had loads of stringing and blobs at 215 C and it knocked itself off the bed when about 1mm fron the top. Second go was better temperature at 225 C and flow rate 95% bed at 60 C :

Not too bad, a bit of hairiness where the writing is and a bit of "Elephants Foot". Size was pretty close to design. Most obvious difference to PLA was that it was barely stuck to the bed (using PVA) and just pinged off when I pushed it, I normally have to take a stripping knife to remove PLA prints. It is a translucent PETG filament and you can see the infill quite well. If you print at too low a temperature the filament goes opaque.

Had an interesting time with the first print as the filament was "cross-threaded" and jammed on the reel. I ended up with about 20m of the stuff on the floor so that I could undo the knot and rewind it.

Looks to be a useful material definitely tougher than PLA.

John

Yep, I remade a clip on holder for my tripod, in PETG it is more flexible and less brittle than PLA.

I ended up at 130C though.

Back to PLA now and under extrusion on demanding bits. Measured the filament and its 1.70mm, I'm sure the difference is visible! (I know it's only 2 thou!) That's 6% under extrusion, waiting to see if a repeat of the test print is OK..

Neil

Hate to rain on Paul Lousick's parade but PET is a long way from being the most common plastic, useful and widespread though it is. The most recent figures from Plastics Europe (which exclude fibre) show that we used about 3 million tons of it in 2016. The polyolefins (polyethylene and polypropylene) add up to over 23 million tons. Total EU demand for all plastics is about 49 million tons per year, so PET is about 6 - 7%. PVC and polyurethanes both outperform PET.

I stand corrected Norman and am always open to learn more. Should have said , "one of the more common plastic's.

My knowledge of plastics is not extensive and comes from the college of Wikiopedia and Professor Google.

Paul.

I hope nobody minds if I resurrect this thread?

I have just tried making prints with PETG. The first went OK, but there were parts of the print missing.

The second and third attempts failed because the parts came away from the base during printing, leaving a complete twisted mess.

I notice some mention using PVA on the bed to stick the prints down, is this a normal procedure?

Diluted PVA painted onto the bed will help with adhesion problems. Dilute the usual PVA wood adhesive about 50/50 with water paint on and let dry. The bed still needs to be very clean, a wipe with kitchen paper and bioethanol or similar fixes that. More important is getting the first layer height correct, if the plastic is not pressed down well to the plate it won't stick. Also with PETG the temperature needs to be correct, it has a higher melting point that PLA so make sure you have set the temp correctly. May still need some experimentation with temperature to find what works best for your particular filament. Too high a temperature will result in lots of stringing (fine hair-like strands) the stringing tends to stick to the outside of the nozzle and can cause problems.

I find that PETG is a very good filament to work with once you have cracked the problems. I rarely use PVA now except for larger prints that often want to lift at the corners.

Good luck

John