Benchy Help  

New Member

Hello Prusa community,

I purchased 4 printers for our school, 2 minis are on their way (hopefully 🙂 ), and I am part way through building the second mk3s kit.  The first one is up and running, but not as cleanly as I would like.  I have done a couple of prints that have been partially successful, but not to standards.  I did the traditional Benchy test, and need some help diagnosing the issues to get things running.    I did find a guide on reddit ( ), but was unable to find exact fits.  Maybe more than one thing is going on?  I know that we have a great community, and am hoping for some help in the diagnosis.  This is my first time building a kit.  I have no problem tinkering given some guidance.

I have not changed any of the settings yet.  The Benchy file is the original from the SD card.  All heat settings and speed settings are default (if I need to change those, I would need to learn how as well 🙂 ).

Thank you in advance for your help.

Pictures are attached:

Benchy photos 1-6

Kind Regards,


Posted : 02/12/2020 3:08 pm
Estimable Member

I'm wondering if you need to tweak your Live Z calibration, its very important to get the first layer spot on.  The Prusa test print is very difficult to see, much easier and better to print a 75mm square or similar. Theres a helpful article here:

Lucky children, I wish there had been 3D printers when I was at school 😀 

Posted : 03/12/2020 1:53 am
New Member


Thank you so much for the reply!  I will check out your resource.

I ended up spending a few hours with chat last night.  They had me download the 3.8 firmware and flash it instead of using the 3.9 version.  It seemed the 3.9 version was giving inaccurate numbers for belt tension.  Once we got that rolling, and several adjustments of y axis tension, it is printing much better now.  

I wonder if anyone else has had issues with the belt tension readings on the 3.9 firmware?

And the students definitely have it good!

Once again, thank you for the reply.

Kind regards,


Posted : 03/12/2020 2:01 pm
Lize liked

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