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end of print retraction problem?


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Posted · end of print retraction problem?

Hi all


I have 3 ultimaker 2 printers upgraded with Olsson block's and Bondtech extruder's. At least 50% of the time, the machines fail to print the first layer of a new print and i have to abort the print, remove the bowden tube and trim the 'blobby' filament back. Once I've done this, the printer works perfectly . This happens to all three printers.




Its driving me mad... Today I have replaced the bowdens and PTFE couplers on all machines hoping that it would resolve the problem - still does it!


Any thoughts? I'm running out of ideas!

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    Posted · end of print retraction problem?

    There are at least two known problems with the filament retraction at the end of a print. These problems have been fixed in a beta-release but did not undergo the full test procedure.


    I'm sad to say that the UM2 development is in an 'end of life' state which means only huge bugs will be fixed. The mentioned beta-release is there for almost a year but gets no priority. 

    I'm looking for people to give this beta-release a try. So far there has been little response, but the reponse I did get was positive. With more positive results from beta-testers this release can be made into an official release.

    The UM2+ firmware can be found here: https://github.com/Ultimaker/UM2.1-Firmware/tree/UM2.1_JarJar/releases/beta

    And the release notes:  https://github.com/Ultimaker/UM2.1-Firmware/commit/f6e69344c00d7f300dace730990652ba614a2105


    Please give this a try on one of your printers if your model is a UM2+. You can upload the firmware through Cura. Reverting to the original firmware is always possible, the original firmware is provided with Cura.


    Report your test results back here. Without positive reports I can't get the momentum for releasing this update.

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    Posted · end of print retraction problem?

    Thanks for the reply and the beta firmware links.


    The printers are in a school workshop and all three printers are identical, so it will be interesting to see if the firmware improves things. I have passed on the github links to our IT department and asked them to install the firmware on one machine so that I can compare. I will get back to you with the results


    Thanks for your help

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    Posted · end of print retraction problem?

    If you purge more, for example by printing ten lines of skirt, doesn't it come through? Or if you manually purge a bit of material before the print? Or is that blob sitting in the way and somehow blocking the movement of the filament?


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    Posted · end of print retraction problem?

    I think i have found the problem... the machines are ultimaker 2 but with Olsson blocks and bondtech extruders fitted. These mods were done three years ago before the ultimaker 2 plus upgrades were available. Bondtech supply their own flavour of firmware and also a small E-step programme. A few months ago, we upgraded Cura to the latest version and downloaded the latest firmware...


    I have done a 'factory reset' on one machine and installed the original bondtech firmware and E-step g-code, tested the printer with a small model multiple times and the problem seems to be fixed. Thanks for the input; it has helped in a roundabout way by jogging my memory of the bondtech firmware... one of those 'light-bulb moments'

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