Using PETG Filament With the Mendel90 Printer

PLA has been my favorite filament to use in my Mendel90 printer for many years.  It’s always been very easy to work with and has produced consistent results.  PLA sticks easily to a heated bed and yet releases without any effort once cooled.

The main drawbacks to PLA are its low melting point and tendency to be hard yet brittle.  These properties make PLA unsuitable for some use cases.

I’ve experimented with ABS in the past but I was never able to get good results using it with my Mendel90.  For me ABS has always been a pain to work with.  When I first started working with ABS I couldn’t get prints to stick to the bed.  Once I solved that issue I couldn’t get prints to release from the glass.  ABS also has a horrible tendency to warp and curl off of the print bed too.  To top that off it creates a toxic smell while printing.

PETG the Miracle Filament

I first learned about PETG (glycol-modified polyethylene terephthalate) while researching the D-Bot printer.  PETG seems to be becoming a popular filament for printing RepRap printer parts because if its strength and temperature resistance.

PETG combines the best characteristics of both PLA and ABS without the negatives.

Benefits of PETG

  • Strong and durable (like ABS)
  • More flexible than PLA
  • Temperature and chemical resistant
  • Easy to print with
  • Odorless
  • Doesn’t warp like ABS


  • Hydroscopic (absorbs water easily)
  • Some stringing issues
  • Very sticky (not good for support)

Using PETG With the Mendel90

Since I’ve had great results using Matterhackers PRO Series PLA in the past, I decided to order some of their PRO Series PETG filament.   So far their PETG has worked great with my Mendel90.

PETG prints come out with a really nice glossy finish to them.

Test print using PETG on the Mendel90.

Printer Settings

I’m currently using an extruder temperature of 245C with the bed set to 65C.  I’ve also been using a light spray (2-3 seconds) of hairspray on the glass bed to help with adhesion but mostly to make prints a bit easier to release.  PETG seems to stick very well on heated glass, sometimes a little too well.

Coat the bed with a little hairspray before printing.

Since PETG requires a higher extruder temperature than PLA I had to adjust my Z calibration slightly to account for increases in thermal expansion of the nozzle and bed.

I’m still dialing in the exact settings for my PETG profile in Skeinforge but my prints are coming out really nicely so far.  I’m planning to print all of the parts I need to build a D-Bot printer using PETG so I expect to have plenty of time to finish tweaking my settings.

The begging of a D-Bot printer using PETG filament.

If you haven’t tried printing with PETG yet I highly recommend giving it a shot.  I think you’ll be very surprised how easy it is to work with.






Sam Kear

Sam graduated from the University of Missouri - Kansas City with a bachelors degree in Information Technology. Currently he works as a network analyst for an algorithmic trading firm. Sam enjoys the challenge of troubleshooting complex problems and is constantly experimenting with new technologies.

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