Filament Notes


More filament notes

There’s a wealth of information available on filaments and materials out there, so I’m just going to stick to notes on specific issues I’ve encountered.


These notes are based on my experiences with the Prusa i3 Mk3 printer. If you are using a different printer, please verify the hardware details are same. These pages may be a bit rough as I revise them and add new material. Please check back regularly for updates.

Filament reviews, master lists, and comparisons

A few brave souls are trying to maintain comprehensive reviews and/or comparisons across the range of filaments available.


filament comparisons

Calibrating new filament


Filament calibration routine.

You can use generic settings for most filament types, but a bit of fine tuning can help with over- or under-extrusion, stringing and other quality problems. I like to do these tests in this order as time allows if I’m planning on using a new filament extensively.

Filament diameter

Measure at multiple locations over 1m/3ft. and average. Enter into slicer filament settings.

Extrusion width

Print hollow cube with 2 external perimeters at 120% of nozzle size. Measure top center of 4 walls and average. Divide expected value (2 * 1.2 * nozzle size) by average of measured values. This is your extrusion multiplier. Enter into slicer filament settings.

Linear Advance

Print test print. Select most even line. Enter corresponding value into slicer filament startup gcode.

Maximum volumetric speed (rate)

Start low (e.g. 5) and increase until extruder clicks, skips or jams encountered. Back off.


Print temperature test tower. Select value providing least stringing, best overhang and overall quality. Enter value into slicer filament settings.

Printing with PETG

PETG is a great material, but can be a bit tricky to print compared to PLA. If you’re aware of these differences starting out, you can save a lot of heartache and frustration.

  • PETG is attracted to hot metal, so try to keep your bed is at hot as possible and the extruder is a cold as possible at the start of your prints. After the first layer the extruder temperature can be raised and the bed temperature lowered.
  • Consider a coated nozzle and/or heater block silicone sock to reduce tendency of PETG to jump onto the nozzle and heater block.
  • When switching from PETG to PLA, heat the nozzle above PETG temps and use some cleaning filament to clear the hotend and nozzle of any residual PETG. This is not 100% mandatory, but the cleaning filament does a good job of pulling out all the PETG, and will also melt out at PLA temps, so any stuck won’t screw up lower temp PLA prin
  • PETG is prone to snagging onto the nozzle if it’s too close. Some Live-Z adjustment for PETG is recommended. I raise mine (make less negative) by 0.02mm, though others swear by 0.2mm. See what works best for you.
  • You don’t need an enclosure for PETG. It’s pleasant to work with at normal room temperatures.
  • Keep PETG in sealed bags with fresh desiccant when not in use.
  • Most PETG will print fine on the PEI sheet with a spritz of Windex and/or wipes with your fingers. However, hotter stuff (>250C on 80C+ bed) may stick too well. Consider gluestick or some other release agent for hotter temps.
  • Reserve one PEI surface for PETG and other hot sticky materials, and a separate surface for PLA.

Temperature ranges


Notes on temperature deflection

Every filament has a maximum “heat deflection temperature”, often indicated as Tg (for glass transition temperature), above which it will distort or melt. Different materials can vary signifcantly.

Table 12 Temperature deflection characteristics for common filament types
Filament Type Max. Temperature
Colorfabb HT 100C/212F
Colorfabb NGEN 85C/185F
PETG 80C/176F
Colorfabb XT 75C/167F
PLA 60C/140F
Taulman Bridge 52C/125F

Contact and feedback

You can find me on the Prusa support forums or Reddit where I lurk in many of the 3D printing-related subreddits.