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  1. #11
    Technologist TommyDee's Avatar
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    Typically, just slowing the print itself down will take care of a lot of common issues. You can dial the retract details from there. Get good results and proper dimensions on your test piece and you have a good "detail" profile for whatever filament you are running. Now you can start speeding it up and see what your print quality limits are before a little more tweaking needs to be done on the other dials. It really does test the patience of the most hardened geeks and they are relentless! (No offence to geeks = cred')

  2. #12
    Starting to hear the occasional thud when my printer is laying down the first and second layers, is that anything to be deeply concerned about or might it be from setting the retraction settings to about 70-80mm/s (Where Cura has the text box go warning yellow)

  3. #13
    Technologist TommyDee's Avatar
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    Clunks are bad! It typically indicates something is loose and it is heavy and reacts to sudden velocity changes from a stepper motor.

    Typically these can be found by putting a finger in a safe place near the suspected member of the system that would provide positive feedback.

    There is also something quiet common but not often associated with a mechanical "clunk". That is filament stripping by the filament driver gear. If the velocity of the filament feed is greater than the nozzle can melt and output, then the next weakest link will give. In this case, that is the filament driver gear. If it cannot drive filament forward, it will simply strip the filament and skip that particular advancement. Excessive stripping will fail to forward the filament for the remainder of the print. This excessive case is easily noted by studying the filament and looking for a scalloped section of the filament where the driver is just free-wheeling.

    In my case, the stripping of filament has a very distinct sound. Hopefully that is all your are dealing with. That simply means you need more temperature or reduced filament velocity.

  4. #14
    Only seems to have happened when I upped the retraction distance and speed, do you think it went too far back and might have caused some stripping issue? I also noticed on the spool that the temperature range is 205-225 (I thought that was a serial number at first) and the printer runs at 205C nozzle by default. Should I up it to about 215C-225C? On top of checking the filament for stripping of course.

  5. #15
    Technologist TommyDee's Avatar
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    Yea, hitting the middle of the specified temperature range is a good starting point. There are a lot of other calibration issues in the chain that may give you erroneous readings though. I know my machine is typically 5 degrees cooler at the nozzle due to cumulative inaccuracies. I take this into account with recipes.

    Then again, there is no reason not to start at the high end if you know your machine reports a temperature that is pretty close to the actual temperature. Give it a +/-5 degrees C hedge either way. The reason I say this is because the upper end of the temperature is better flow. When you've gone too far, you will get other heat-creep issues. For instance, my canned configurations run 250 degree C materials (PETG) but its initial layer 1 temperature is 265! Same with PLA, 235C for a print that continues at 215C after the first layer. I suspect this is to get the print moving sooner while heater core elements are still normalizing their temperature. To me, this is a poor implementation but they know a lot more than me.

    Maybe try this first layer temperature trick(?)

  6. #16
    Sorry I've been so quiet, was trying out some different print settings before I posted again. On that note, managed to fix the unsettling thudding by setting my print temperature to 215C but still have the plastic drooping on the edges of the print along with stringing along the infill no matter what retraction settings I try.

  7. #17
    Technologist TommyDee's Avatar
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    Sounds like progress

    You are balancing velocity; feed speed; retract reaction time.

    So the clunks could have been strain on the filament driver mech?

  8. #18
    Sounds about right, so that means I can't go over 70 mm/s retraction or it will start clunking again. Trying to set it between 2-5 retraction distance but no effect. Only other setting I can think of is to up the layer height to .1

  9. #19
    Technologist TommyDee's Avatar
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    More gap, more feed.

    Retraction is a strange animal. In g-code is is a combination of M227 and M228 commands. There is a pullback and a resume value for M227. This is a kind of pre-purge option.

    Have you tried disabling the retractions? This is an appropriate option in some cases where it is seriously detrimental in others. However, it is one less parameter to deal with to get your move velocity and you feed velocities to work. Then go back and add the "destring" or "Deblob" operation, that retraction provides.

  10. #20
    Ah- Umm...*Checks settings*

    Huh, you can in Cura. I will give that a try... Thank you.

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