Longest print yet for my Prusa

This past weekend I completed the longest continuous print yet on my Prusa Mendel…just under 9 hours straight. It’s the Basalt Pencil Holder from Thingiverse. It was printed at 100% scale, 0.20mm layer height with 0.10 infill on a J-Head with 0.35mm nozzle in translucent green PLA.

It reached 89.8mm in height (one of the taller things I’ve printed) and turned out amazingly well. It’s solid, dense and nearly a perfect print with minimal stringing.

Basalt Pencil Holder

Basalt Pencil Holder

The Prusa seems no worse for wear either:
Basalt Pencil Holder

One trick that Brad (Sublime) discovered when testing the J-Head with Slic3r is to tell Slic3r that the 0.35mm nozzle is actually 0.30 which seems to better compensate for the swell of the nozzle under heat and results in less blobbing. Since I updated my profile with that change, the prints have been much cleaner.


  1. Luis Andrade says:

    Hi John,
    Great tip regarding the nozzle. I will try it.
    Which speed did you configure in Slic3r? What about retraction settings?
    Thanks in advance.

    • John says:

      Luis: I don’t remember my settings off the top of my head but I’ll email you my config file tonight.

      • Luis Andrade says:

        That’s great, thank you very much!
        Excellent work with your Prusa, congratulations.

        I have finished building mine and now I am looking for the best Slic3r settings for it, but I’m getting pretty good results already.


  2. That’s really cool, John!

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