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Pause at z plugin in cura and change material

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Hi,

I have an Ultimaker 2 for just over a week now and I am figuring out on how to use the Cura plugin pause at z and changing material.

When the printer pauses, I change the material. But after resuming there is no material coming out of the nozzle and is printing in mid air. I tried the default of 5mm retract in the plugin and also 20mm which was advised in another thread. I also tried to use the material move function, but that is not available when the printer is paused. What does work is manually pausing the print and changing the material. But I want to be able to stop at an exact z layer.

I use Cura 15.04.3 and have updated the firmware of the printer included with that version.

Does anyone know the correct settings to successfully change the material on a specific z?

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Providing that you use the (standard) gcode flavor "UltiGcode", the Ultimaker2 uses volumetric values for the E-axis....and so does the Pause at z plugin (i think...).

You have to calculate the retraction amount for the plugin in cubic millimeter.

If i remember right, the change material wizard retracts the filament 20mm at the end of the procedure.

The solution for me was to increase the plugin value "Retraction amount" to approx.128 (for a filament diameter of 2.85mm). This compensates the 20mm retract when you resume the print.

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...

The solution for me was to increase the plugin value "Retraction amount" to approx.128 (for a filament diameter of 2.85mm). This compensates the 20mm retract when you  resume the print.

 

That worked beautifully!

I understand now that the plugin assumes length, but the printer needs mm3. So you got the 128mm3 by calculating volume: 1/4 * pi * d2 * h.

Or 0.25 * 3.14 * 2.85 * 2.85 * 20 = 127.52mm3.

Some of my 2.85mm filament measures 2.80mm. I am curious if I should change the formula for 2.80mm or let the printer deal with the 2.80mm volume calculations. I have added a new material called "PLA 2.80" which has a 2.80mm diameter definition.

Edited by Guest
left out the last few words.

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Using Robert's feeder works perfectly for changing filaments mid-print. Just press Pause on the UM2, pull the filament from the back, insert the new one and resume printing. Simple as that! Of course, you have to visually judge yourself when you should press pause (not as exact as using Z)...

Edited by Guest

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