Printing tricks

Something for printing petg

  • Monday, 30 November 2020
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 Guide ,How to print PETG successfully

 

PETG, short for polyethylene terephthalate glycol, is a tough, temperature-resistant, and highly impact-resistant plastic often used in FDM-style 3D printing.

 

Here, we’ll take you through how to successfully print with PETG and help you troubleshoot common issues. While printing with PETG is certainly less challenging than with ABS, it does have its caveats, which we will address.

Watch out for:

·         Nozzle temperature

·         Bed temperature 

·         Bed surfaces/adhesion

·         Retraction settings

·         Fan speeds

·         Support settings

·         Moisture absorption

 

Initial Settings

If your slicer has built-in PETG material profiles, those will be a great place to start. Otherwise, you can take your ordinary PLA settings and make a couple of changes:

·         Increase the nozzle temperature as per manufacturer recommendations (usually between 220 and 260 ºC)

·         Increase the bed temperature as per manufacturer recommendations (usually between 50 and 85 ºC)

·         Decrease fan speeds to somewhere in the range of 20 to 50 %

 

Tip #1: Use Glue stick or Hairspray or spray paint

 

Tip #2: Get Retraction RightPETG has a high tendency to string and ooze

Tip #3: Prevent Cracking

Tip #4: Give Support Structures Space

Tip #5: Keep PETG Dry

Printing with PETG Filament

PETG will typically flow nicely in the range of 230-265°C. Print too hot and excessive stringing or blobbing will occur; too cold and it may jam or delaminate easily. Since exact thermal properties vary from spool to spool, you’ll want to experiment with any filament you buy to determine the best temperature at which to print.

Getting the first layer right

As it is with printing any type of filament, getting a good first layer is essential to a successful print. Without a good first layer you will likely need to reprint the item, so it’s imperative that you know what it takes to start a print off right so it can build to completion.

I experimented with a few different types of beds and adhesion methods, and the best practices I found are listed below.

Printing on glass

Glass is very smooth, which imparts a glossy surface onto the printed part. Printing on glass requires a heated bed. We find that unscented hairspray on a heated bed (50-60°C) works best on bare glass. Fair warning: some users have reported that PETG has stuck so well to their glass bed that chunks have been torn out of it. Print on glass with caution.

Getting the Right Temperature

Keep an eye on how much filament doesn’t end up where it’s supposed to. PETG plastic is prone to stringing and oozing, so watch for filament that ends up stuck on the nozzle. Sometimes blobs of PETG filament will stick to the nozzle and then end up deposited on another part of the print where it’s not supposed to be. If this happens it will cool and harden, which can be a hazard for the nozzle the next time it moves into that space. The result is usually a layer shift, which can be detrimental to the print.

Getting the first layer right

As it is with printing any type of filament, getting a good first layer is essential to a successful print. Without a good first layer you will likely need to reprint the item, so it’s imperative that you know what it takes to start a print off right so it can build to completion.

I experimented with a few different types of beds and adhesion methods, and the best practices I found are listed below.

Printing on glass

Glass is very smooth, which imparts a glossy surface onto the printed part. Printing on glass requires a heated bed. We find that unscented hairspray on a heated bed (50-60°C) works best on bare glass. Fair warning: some users have reported that PETG has stuck so well to their glass bed that chunks have been torn out of it. Print on glass with caution.

Getting the Right Temperature

Keep an eye on how much filament doesn’t end up where it’s supposed to. PETG plastic is prone to stringing and oozing, so watch for filament that ends up stuck on the nozzle. Sometimes blobs of PETG filament will stick to the nozzle and then end up deposited on another part of the print where it’s not supposed to be. If this happens it will cool and harden, which can be a hazard for the nozzle the next time it moves into that space. The result is usually a layer shift, which can be detrimental to the print.

 

Troubleshooting

Several issues can arise during a PETG plastic print. Here is an overview of some of the more frequent problems with printing PETG filament and steps you can take to correct them:

The first layer PETG filament will not stick to the bed.

If PETG filament globs onto the nozzle and gets dragged around instead of sticking to the bed:

1.    Make sure you have the right bed surface for PETG: 1) blue painter’s tape without heat with or without glue stick, or 2) plain glass needs heat and (unscented) hairspray. 

2.    Make sure you’re printing at the right temperature and that your bed is the right temperature. 230-265°C extrusion temperature. 50-60°C bed temperature

3.    Make sure the print bed is level. Use Software Print Leveling to be sure.

4.    Make sure the extruder is at the right height, and if not either 1) adjust the Z Offset for the extruder or 2) adjust the printer’s limit switch (if equipped).

Check the ambient temperature. If it’s too cold, your print can be negatively affected. Ideally you want it room temperature or hotter for PETG.

The printed part has bad infill and and top surfaces.

When filament intended for the infill and/or top surfaces ends up globing onto the nozzle instead:

1.    Make sure the extrusion temperature is not too cold. If you’re closer to the lower end of PETG’s printable range (230-265°C), bump up the temperature five degrees at a time until extruded filament flows nicely out of the nozzle and stays where it’s extruded.

2.    Slow the print speeds down 10-20%, either with or without bumping the temperature up. Speed and temperature are directly related with regard to getting a nice flow.

3.    Check the filament tension.

Clean the filament drive gear (if needed).

The outside edges of my PETG prints have lots of little bumps on them.

Artifacts on the outside of printed parts can occur for various reasons.

If your printer stutters when connected to a computer:

1.    Make sure that the computer is not too busy to feed the printer commands. Running applications other than the printer-control software at the same time as a print will use a part of the computer’s memory. If enough memory is used by other programs it is unavailable for the printer communication and the print may suffer.

2.    Print from SD card. On some printers you can try and print from SD card.  This often helps the printer have enough data to run more smoothly.

If the filament pops as it comes out of the nozzle:

1.    Dry the filament. Wet filament will hydrolyze as it melts and will be significantly weaker than filament printed dry.

The quality of your filament will have a big impact on the quality of your part. Getting better quality PETG filament will help you produce better parts. However, don't be too quick to assume the problem is in your PETG. With good settings and patience, hobbyists have succeeded in printing all sorts of materials many of which have very low viscosity and inconsistency. You should be able to get at least usable parts even with some lower quality filament and the right settings.

Tall sections of the prints look melted or squished together.

1.    Turn on cooling fans for that section of the print.

2.    Lower the temperature and speed.

3.    Print more than one part to give the layers time to cool as the nozzle works its way back and forth between the parts.

Use a small fan. If your printer does not have an integrated fan you can use a small desk fan. Just make sure that the fan does not cool the hot end.

The printed part is curling off the bed.

While it does not happen with PETG as much as with some other filaments (like ABS filament), warping can occur and destroy an otherwise perfect print.

If this happens, use more bed adhesion (depending on your bed surface). 2-3 layers of glue stick on the bed is usually enough for sufficient first-layer adhesion on blue painter’s tape, and a 2-3 second spray of hairspray should suffice for glass prints.

Avoid uneven glue stick application, or incredibly thick layers of it that could interfere with the print.

The printer will not extrude any material.

If the extruder is turning properly but no filament flows:

1.    Make sure your hot end is getting hot. Check that the hot end is heating at all. If it is not you need to have your printer serviced or figure out why. It is likely a loose connection or that the electronics board suffered a short circuit (assuming the printer is still connected and responding to your host software).

2.    Slow down the print speed. If your hot end is hot but the print is going too fast, the filament might not be able to fully melt before it’s pushed through the nozzle. If this happens, back pressure can build up and the filament will start to grind against the extruder gear.

3.    Clean the drive gear and adjust tension. If the extruder gear grinds on filament, over time the gear will have less grip. You’ll need to clean the gear with a brush to get the tiny pieces of plastic, then make sure your tensioner is solid against the filament. Too much tension can also prevent extrusion and is more common with direct drives.

4.    Remove the any obstructions. It may be that you have a small particle in your extruder tip jamming the plastic. Push some filament through by hand to clear any obstructions and allow the filament to flow nicely.

Check for and remove jams between the extruder and hot end.While uncommon with PETG, jams can still occur. If the filament breaks off in the hot end or a piece won’t come out you might have to take your hot end apart, clean out any pieces that aren’t where they’re supposed to be, and put everything back together again.

Thank you for reading How To Succeed When Printing In PETG.

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