PETG Printing Issues !!!

Good morning folks.. so im working on PETG, as I think its a great option for parts for my customer.
Ive had some successful prints in calibration cubes (but they dont have many retracts etc).
THe first actual part im testing did not turn out great.

1. Starting with the very first layer, after the outside shell 2 layers were layed down the rest of the inside never quite reached the edge to bond with it. It caused the outside layer the entire way up the print to not be bonded well. You can see it in the first picture below it actually bubbled out.
2. Weakness. THe piece i broke off, the other piece I broke off... Its just not strong. Do I need to be printing hotter? Im printing about 230 (esun clear petg). Ive been told hotter is a better bond for this stuff of course, but ive also seen that anything above 235 the filament gets super cloudy and not clear at all... Not a big deal for production, as ill be using white. Just saying :)
3. Retraction settings are 22mm/s 1.7mm retraction, and 5mm wipe distance... still had 2 big globs on the print.

I really want to dial this filament in. any help would be great.

Taz 5
No layer fan on
230 degrees
bed 90
35mm/s

THanks

http://i1132.photobucket.com/albums/...psyb2mlzwd.jpg

http://i1132.photobucket.com/albums/...pshmfi3y11.jpg

[QUOTE=dunginhawk;69441]1. Starting with the very first layer, after the outside shell 2 layers were layed down the rest of the inside never quite reached the edge to bond with it./QUOTE]

duninghawk,

In Slic3r, set your Print Settings > Advanced > Overlap > Infill/perimeters overlap to a higher setting. I use 10%. This compensates for the infill deposition not quite meeting the perimeter deposition.

There should be a similar setting in other slicers.

For the rest, I use 35% hexagonal infill for everything that's not hollow. I can't help with your retraction, we do it differently (pulses to motor, rate and dwell time).

Davo.. Thanks for the response... I am using 15% overlap anyway... Perhaps I need to up that even higher. Although the guides ive read dont suggest going higher. Strange. the rest of the part is not bad. I think i just need to raise the temp to get the bonding better.

I did print some pet a while a go.

Can't honestly remember what temp I used but 245 seems to ring a bell.
Definitely didn't have any bonding issues.
hang on it's in a thread here somewhere - brb

What kind of search won't let you use 3 letter words or acronyms ? This forums poxy search facility is the answer.

yahoo search works better - but in the end I just went to my profile and threads started :-).

Quote:

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It's printing great on pet tape. I initially printed the clip at 230. And it just fell to bits, the pla one was bendier and more durable.
So I'm printing another one at 245. To see if I was having layer adhesion issues with the first one.

But is there any definitive way to tell if it's abs or pet ?

ps. second clip definitely a lot better. Bends way past the point the last one broke at.

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And yep - at 230 it does just fall apart.
Try it at 245.

Far as I can remember, I printed about 10 clips and none have broken yet.

I usually use google to search sites:

https://www.google.com/search?client=opera&q=pet+site%3A3dprintboard.com

Thanks curious. ILl try running a bit hotter. I love the flex this stuff has and if i can get it dialed in im sure it will be better than ABS or PLA by a long ways. However im off to Home depot to buy a shelving system and some PLexi to build an enclosure anyway :)

Curious, what layer height did you print at? did you have any issues getting your inside to adhere to your shells? i have a gap even with a 15% infil overlap. Ive heard you dont want to squish PETG, but it looks like thats the only way im going to get out to the perimeter. which is fine.

for the clips i printed at 0.2mm
according to simplify3d I use an outline overlap of 20%

I've never messed with it and never had any issues.

did you smoosh your bottom layer a bit? or just a standard pancake style?

none of the above :-)

Just printed them. no brims, rafts or pancakes were involved.

It sticks to pva covered pet tape with no problems.

bed adherence isnt a problem.. PEI works quite well for it, im just not getting layer bonding, which will be helped by higher temps... ill try some things out :)
thanks

Are you sure you have actual PETG and not another PET type (there are many different types of PET, PET-G is most suited for 3D printing) ?

I have printed a lot with 6+ colors (colorless, black, red, blue, green, yellow, translucent red etc) of PETG with exellent bonding. The parts are super-strong. The only problem I have is that it is virtually impossible to print supports in PETG as they are a PITA to remove as the bonding is so strong.

My settings are Flashforge Creator Dual, 225-230 C nozzle, 80 C bed (3Dlac spray on glass), 0.25 layer height, sliced with Simplify3D using slightly adjusted ABS settings (and without raft or other supports).

I was doing much taller layers .4 I believe, and wish no smoosh at ALL on the bottom layers im guessing the bonding was just bad from the start.
Yes im sure its petg, esun brand. Support being super strong will be an issue too because my customers parts have a lot of it, in some tight spaces haha.

One of my biggest issue with PET was when I left the fan on : contrary to PLA this is clearly detrimentary.

For my PB ceramic hot end, I print at 255°C the 1st layer, 5°C below for the next ones. But the reading may be a bit inaccurate. 230 looks low to me. I usually put the bed close to 60°C as well.

For the PB metal hot end the max retraction setting is 0,5mm but with my ceramic hot end I go up to 4mm depending on material. Depending if your hotend is all-metal or not, you could try with less than 1,7 mm.

well I haven't fitted an on/off switch to the fan yet - so that was on.

Like I said had no issues once I ignored the manufacturers recommemded temps and printed at 245.

I actually find that ALL manufacturers printing temps are way too low.
I guess it begs the question - do they test on enclosed printers and is that what makes the difference ?

Quote:

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I actually find that ALL manufacturers printing temps are way too low

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Funny,
I find that the manufacturers recommended temps are too high....but I print at relatively low speeds (40-60 mm/s).

Having said that, it will also depend on the printing/extruding speed I guess. It takes time for the filament to get to the extruding temperature. At high printing speeds, the residendce time in the heated part of the nozzle is less, so the temperature differential (between extruder wall and filament core) will need to be higher to transfer the same amount of energy to heat and melt a given volume of polymer.

Attached a recent photo of a temperature test with two PETG types. Each block is printed at tha same speed settings (3200 mm/min), 0.25 layer height, but at decreasing temperature. This was done on a non-enclosed Flashforge Creator Dual (the old multiplex version). I can go down to 210 without much quality loss. Even the block at 210 is totally bonded. I can not break it off with my bare hands. Even with a pair of pliers it does not break off at a single layer but roughly slanted through multiple layers (it was 15% infill).


Attachment 7449

Alibert... can you post a link to this test STL? this seems like the perfect test to run to get the right temp on my filament.

No probs.

It's the fourth one down: https://www.3dhubs.com/talk/thread/b...ibration-tests

You will have to choose a layer height and then calculate at which layer to switch the temperature. S3D can do this, I don' t know if other slicers can.

yeah i am printing the torture test first... Just got my new taz 5 in tonight (exchanged my old one, had some Z axis issues). First calibration cube was stunningly perfect. Torture test is running.
Definately have to bring that temp test in to slicer and figure out how high the first part is, and the second and so on. I wish there was a guide on that page saying at 100% size. .2mm layers, change temps at 45 layer, 90 layer, etc.

Basically it is the (optional) number of raft layers, with 2.0mm for the base, then 10.0 mm for the the 7 blocks on top of that. With .2 or .25 mm layer height just calculate. Then print one and be present to watch the temperature changing in the display when going from block 1 to block 2 to check. You may need to add/substract a layer for precise tunign to your slicer.

For anyone going to the TCT in B'ham today, maybe I'll see you there!

ok. so i worked it out.
Here are some images.

Starting at the bottom.
First point = 260c
2nd - 255
3rd - 250
4th - 245
5th - 240
6th - 235
7th - 230

I definitely dont like it at 260, too cloudy and almost gritty.
However, anything 250 and below seems to be ok. I think some of my previous issues were first layer problems, which caused some lamination issues later, as well as a much too low extrusion multiplier (74). I have the right number now around 88 i think.

Tips here curled a little bit due to how quickly the layers were being printed and no layer fan. bond seems very strong..
http://i1132.photobucket.com/albums/...pswrmuzknb.jpg

http://i1132.photobucket.com/albums/...psykj8fjnb.jpg

http://i1132.photobucket.com/albums/...pstvdsjbr1.jpg

http://i1132.photobucket.com/albums/...psusbhenuj.jpg

Let me know how this looks to the smarter folks out there :)

thanks

Nice result. The 'gritty' look of the lower layers will be due to small steam/decomposition bubbles. If you dry your PETG you will see less of that.

If you have no problems with the lowest temp (and the layer bonding is still OK), try going even lower. I can easily print down to 200-210 C with my FF. Disregard what anyone advises and do yourown tests. I invariably find that the temperature recommendations are too high.

What you want is no edge curling and nice flat bridging over the hollow spaces, and still good layer bonding. A break test(pliers may be needed) can help you with the latter.

Temperature will also depend on printing speed, at higher speeds you will need a higher temp in order to melt the plastic.

Quote:

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Originally Posted by Alibert

Nice result. The 'gritty' look of the lower layers will be due to small steam/decomposition bubbles. If you dry your PETG you will see less of that.

If you have no problems with the lowest temp (and the layer bonding is still OK), try going even lower. I can easily print down to 200-210 C with my FF. Disregard what anyone advises and do yourown tests. I invariably find that the temperature recommendations are too high.

What you want is no edge curling and nice flat bridging over the hollow spaces, and still good layer bonding. A break test(pliers may be needed) can help you with the latter.

Temperature will also depend on printing speed, at higher speeds you will need a higher temp in order to melt the plastic.

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I have to think the curling is just a result of the very short print time per layer... on my production parts that wont be the case.
.
Bridging though is really tough with petg because its so dang fluid, you have to do like 5 top shells to get it done at all. unless you run a fan on high, which I dont typically do. I hear the bonding is much better without a fan??