Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Da Vinci and PETG
#1
Just got a roll of PETG (eSUN natural) in the mail and it wanted to share notes with all you stone cold foxes.

I have a roll of t-glase (PETT) that I've been playing with. They're both really strong and beautiful, but both showing some strange behavior I would love to figure out.

They print small objects wonderfully. However, I'm trying to print a 14cm box and the first few round of perimeter go down beautifully until things get choppy and uneven.

Extruder - 220-250 (problem at all temps)
Bed - 40-90 (poor adhesion below 60)

I've tried playing a bit with extrusion multipliers, speed, and layer height... all to no avail.

Any ideas?


[Image: petg.jpg]
Reply
#2
This is the exact same issue I reported here https://forum.voltivo.com/showthread.php?tid=8416 (although the first link of the brim image is dead now, sorry). I haven't seen this anymore after switching to the E3D hot-end, but I still think that it was due to bad bed leveleving. You can try printing a very wide brim, wait until the wavy lines begin to happen, then play with the bed screws until it goes away.
Reply
#3
The OEM glass bed warps horribly (and differently at different temperatures).

I got a sample of that PETG I've been meaning to try... it's not much, so I'll have to print something small. I was more concerned with it getting too soft and jamming the extruder.
Reply
#4
Well just tried to print some... doesn't look like I had wavy lines, but the extruder started clicking at the beginning of the second layer and I had to cancel the print.
Reply
#5
[strike]I had some clicking too but dropped my bed temp from 90 to 60 and haven't had it since. I think those extra 30 degrees make it hard for the heatsink to keep the cold end isolated.[/strike]
Reply
#6
Hmm, I'll try again with my AUX layer cooler / extruder cooler fan running... see if it helps. I've already modified the OEM fan shroud and flipped that fan to pull hot air OFF the extruder.
Reply
#7
After many hours and a big pile of scrap PETG, I don't think the extruder jam click is from too high of heat (possibly!). After taming the PLA dragon with better coldend isolation and low heat, I assumed that the PETG was getting too hot and gunking up the cold end. I now think what has been happening is that the PETG wan't getting hot enough and pressure was building up in the nozzle causing the extruder to skip.

Another huge issue (I believe) was that I had my bed slightly too close to my extruder tip. I re calibrated it a little lower and I think this has helped reduce back pressure.

Currently running

Extruder 255
Bed 80
Extrusion ratio .95 (to help with back pressure, maybe?)

Seems to be going pretty smooth, tho I may have a thermistor/connector issue as a few times my temperature reading have gone 'def' and the heater has decoupled.
Reply
#8
I should add that I'm printing at 40mm/s across the board. I tried slower speeds after reading this T-glase advice, but still got clicks and things are going smooth at 40 (for the moment...feels tenuous)

Quote:1. Nozzle Size - If you don’t have a larger nozzle, on the order of .7mm or larger, you can still change the nozzle setting in your slicer. The slicer will allow more material out, thus equating to a larger nozzle. There are limits, but testers of t-glase found they could increase their .5mm nozzle up to .7mm.
NOTE: Nozzles smaller than .5mm will create a rather large amount of pressure on the extruding gears and components, and the line may begin to slip.

2. Layer thickness – As most of us are used to printing at .2mm to .25mm layers, the bonding from thread to thread with t-glase is such that if your part does not require vertical high resolution transitions, you can easily increase your layer thicness/height/size to 70% - 90% of the nozzle setting.

3. Print speed – Due to the 2 points above, you will be allowing more material to pass through the heater block, than you would with standard settings. Because it takes time to heat up a quantity of material, you MUST slow down the printer to allow for this difference. A good place to start is 25% - 30% of your usual speed. The assumptions here is that you are printing hollow items like vases and such that shouldn’t take a long time due to very little infill. NOTE: Do not try printing at current speeds. We want you to be successful and reducing print speed is just as important as a larger nozzle.
http://taulman3d.com/t-glase-features.html

Also, I had read that friction from the filament spool had contributed to PLA clicking in the extruder. I had never experienced that with PLA and my spool feeder:
http://www.thingiverse.com/thing:433194

However, it looks like it might now be a contributing problem with PETG clicking. Going to try
http://www.thingiverse.com/thing:660949

The draw of .5mm+ nozzles is getting bigger... Anyone with a e3d tried PET with different nozzle sizes?
Reply
#9
That makes sense, as the filament wasn't soft or gummy when it started clicking. I'll give it another go with higher extruder temp, and slower speed.
Reply
#10
PETG/PET+ is my favorite filament on this printer with an e3d. I just use my ABS profile, 235/90, and it turns out awesome. By far the best filament Ive used to date for strong parts. Even though it doesnt need a raft to stick to the bed, I print with one anyway so the bed is level in relation to the nozzle when it starts printing the object layers. PETG is soft compared to PLA so the spool location should be alot more forgiving. Since PET sticks to the bed much better than PLA or ABS, you should have a little more tolerance to play with offsets, to keep the nozzle from building up back pressure. Im using simplify3d currently, and can upload my PETG process if anyone wants to use that as a starting point.

From a one foot section of my particular brand of PET, my diameter average is 1.71. Take a look at that if your settings arent getting you to where you think you should be.
Reply
#11
That's great... but not everyone is ready to replace with E3D or similar.
Reply
#12
E3d would change the likelihood of a jam, not every other tweakable aspect of dialing in new filament. I had to dial in petg on the stock extruder in order to print the parts needed for the e3d.
Reply
#13
I think you missed my point. Not everyone wants to rip apart their new printer and swap hotends. I understand the benefits, but I'm not ready to give up and possibly destroy my printer.

I've looked at the E3D and hexagon hotends... and there are two main differences I see between them and the da vinci hot end. The first and most obvious is the heatsinks... that leads me to believe with better heatsinks the da vinci extruder could perform as well. The second is the drive gear... and I'm looking at replacing that with a MK7 gear.
Reply
#14
Quote:I think you missed my point. Not everyone wants to rip apart their new printer and swap hotends. I understand the benefits, but I'm not ready to give up and possibly destroy my printer.

I've looked at the E3D and hexagon hotends... and there are two main differences I see between them and the da vinci hot end. The first and most obvious is the heatsinks... that leads me to believe with better heatsinks the da vinci extruder could perform as well. The second is the drive gear... and I'm looking at replacing that with a MK7 gear.

I think you missed my point, I had to dial in PETG/PET+ on the STOCK davinci in order to print the parts needed for the e3d upgrade. I wasnt posting to say "hey look at me, I have an e3d", it was to give pointers on things to look at to dial your settings in, by someone who already went through it.

With the e3d there was nothing to dial in, it just worked, so it would be pointless for me to offer tips on how to print PET on the e3d. I deliberated on even mentioning the e3d on my initial reply but some folks on here, myself included, follow where other users are at from a hardware/modification perspective.
Reply
#15
Your tips seem to be about PETG on your E3D, not about running PETG through a stock da vinci hotend.
Reply
#16
Fair, since I did mention it.

For me, printing on my best ABS profile worked great, printing with a raft, so that the object starts level in relation to the nozzle and raft. PET seems less forgiving around globs and slightly uneven layers, presumably because its stronger and seems to "set" faster. I also seasoned the outside of the nozzle before each print, which seemed to help solve dragging little bits of filament around. With the stock extruder, the only thing I wasnt able to solve was the rough, almost glittery appearance of small layers, in relation to larger layers in other areas of the object. If you were to print a traffic cone, 3/4 of the cone would be a nice consistent color and texture, but the top 1/4 would be rougher and have different light reflection properties.

I did not have problems with heat creep jamming on stock with PET, but PLA was already printing well enough with heatsinks and an oiler. Raft solved backpressure jamming for me.
Reply
#17
Thank you for the tips and clarification
Reply
#18
Nepenthy, thank you for the info. Also great to know that e3d works as an option.

While printing PET on the stock extruder, did you mess with extrusion multiplier or extrusion width? Did print speed have any impact? Were you using slic3r?

Check out this curious first layer of a PET print. The PET sticks well to the edges, then gets choppy.

Anyone have ideas, maybe this reflects warp of the glass bed?



[Image: FullSizeRender2.jpg][Image: FullSizeRender1.jpg]
Reply
#19
Isaic,

I was using slic3r at the time, and do recall having to speed the first layer up a little, to get away from lines coming out wavy, like a ribbon blowing in the wind. If your first layer is kind of choppy, with alot of little peaks, you could probably benefit from speeding up a little. I would venture to guess that while you are watching the first layer laid down, you can see the filament bowing up in spots, yes?

In your picture where you can see the obvious difference, is that just the light/flash or does it look like that from all angles?
Reply
#20
Yes! Absolutely having the filament bow up, speed to blame?

It looks like that from all angles, here is a bed side photo of the difference.


[Image: IMG_1164.jpg]
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)