Original Prusa i3 MK2 – calibration and first printed object

XYZ Calibration compromised.
Front calibration points not reachable.

The solution of this error, the user manual says

Move the left / right Y threaded rods in the Z frame away from you

This is wrong.  I had to pull the Z frame towards me so that the print bed gets closer to the probe.

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Adjustment of Z frame’s position along the Y-axis is not practical.  The easiest way I found is to flip the printer, top of the Z frame seats on the table.  Slowly loosen left or right side M17 nuts backward or forward direction and tighten back enough to hold Z frame. Then do the same on other side. I used a vernier caliper to measure the distance between Z frame and the threaded rod crossing the two threaded rods to keep parallelism. If you loosen the bolts too much, the Y-axis frame will drop.

I suggest taking extra care of Y-axis frame when you assembly that prevents skewed XY plane later on.  On page 44, 12.1 Nozzle/print surface gap is greater in the middle than at the corner describes how to check squareness of Y-axis frame.

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Y-axis belt got loose during calibration.  To prevent another incident, I secured the belt with zip ties.

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XYZ calibration

If X, Y, and Z axis are in right angle, XZY calibration will report perpendicular.

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Self test can’t tell faulty connection of the Hotend thermistor, which implies the user manually decide the thermistor’s condition.

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I ran into bad connection of the Hotend thermistor during the troubleshooting of Mesh bed leveling failure.  When I turned it on the printer, it shows MINTEMP ERROR. Then Hotend temperature was 19 degrees Celsius which was five to six degrees lower than room temperature.

Out of curiosity I ran Preheat. Hotend temperature was at 20 degrees Celsius when K-type thermometer of my multimeter indicated 110 degrees Celsius and kept rising.

I cut the 2-pin connector of the Hotend thermistor, installed new 2-pin connector. And the temperature reading of Hotend became fine.

Failure of Mesh bed leveling freezes the printer.

After successful XYZ calibration, whenever I tried to print a gcode file,  Mesh bed leveling failed and freezed the printer. I spent a whole day to solve this problem.  When it happened, previous calibration data wouldn’t be stored.

Calibration and bed leveling are complete different routine. I have experienced of Marlin, Repetier-Host,  RepRapFirmwar-dc42. Calibration is part of the final stage of building a 3D Printer not a routine that the user chooses as a feature like auto bed leveling. Actually well-built machine does not require auto bed leveling before each printing.

I think this is grave bug that Prusa Rearch will have to fix ASAP.

The error message is:

Bed leveling failed. Sensor disconnected or cable broken. Waiting for reset.

On the user manual and Prusa Research’s support page the solution is:

Verify, whether the PINDA probe cable is plugged into the RAMBo board correctly. If it is the case, the PINDA probe is broken and it needs to be replaced.

I doubted it because XYZ calibration, Z calibration were successful many times. If it was bad connection of the probe cable, calibration would fail too. I thought it caused by firmware at some point. Later on out of frustration I remembered the suggestion of a user on Prusa Reasearch’s forum saying wrong probe’s height might trigger such error.

The fix was to lower the probe height 1.00 mm or 1.50 mm.

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The first print

 

I ran V2calibration.gcode in the SD card three or four times to find the correct Z height, which was -0.800 mm.

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Pug Buddy
(http://www.prusa3d.com/printable-3d-models/)

The layer height was 0.15 mm. It took one hour forty minutes.

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About janpenguin

Email: janpenguin [at] riseup [dot] net Every content on the blog is made by Free and Open Source Software in GNU/Linux.
This entry was posted in Reprap 3D Printer and tagged , , , . Bookmark the permalink.

2 Responses to Original Prusa i3 MK2 – calibration and first printed object

  1. Aaron Yourk says:

    You may want to consider updating your post to include the following diagram:

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