Perplexing E-steps and Flow calibration problem



  • Ever since I upgraded my Ender 3 with a DuetWifi I have been having extrusion problems.
    I recently bought a genuine Titan Aero to try to remedy the problems, as well as for the ability to print flexible materials more easily.
    After I installed the TA I calibrated my E-steps and ended up with 407.5 (1.8 step angle, 7.3 hob diameter, 3:1 gear ratio). After this I did a flow test by printing a single-layer cube and measuring its sides. I measured an average .44 mm when It should've been .4 wall size. When I adjusted my flow to 90.9% to match the results from this test I got major under-extrusion ( huge gaps between lines of filament). I had to raise my flow to 105% to get good extrusion.
    I measured my filament's diameter over a few meters and saw an average of 1.74 mm, and getting as low as 1.73 mm.

    The other issue I'm seeing is that when I print a XYZ test cube with the value for flow that gives me good results (105%), I will get significant over extrusion on the first 6 layers (I use 6 top and 6 bottom layers). These bottom layers bulge out about a mm farther than the rest of the cube. The rest of the cube looks great. I have to resort to adding a post-processing script to bring the flow of these 6 lower layers to about 85% flow to get a decent looking cube. I am really puzzled by this issue and want to know if anyone has encountered anything similar or knows what could be the problem.
    Thank you in advance for any help

    Additional info: using Cura 4.0, Hatchbox PLA, .4 mm Nozzle size, .2 layer height, 60 mm/s print speed.



  • @ezln137 said in Perplexing E-steps and Flow calibration problem:

    I measured my filament's diameter over a few meters and saw an average of 1.74 mm

    Not sure what's going on but just wanted to be sure you know that when you measure the filament (good on you!) be sure you measure around the filament at each point you check.

    I just measured one this AM that was 1.75 at one point, but went down to 1.69 when measured clockwise 60° at the same point!!

    Same point on the length, but be sure to measure a few places around the diameter too.



  • Great suggestion. I measured all around the filament and I did see some variation, but not as big as what you mentioned. With the different measurements the average gets closer to 1.75 mm.
    Thanks for the reply, I'm gonna keep experimenting with settings to see if I get better results.



  • Is the first layer going down smoothly? The over extrusion at the base but under extrusion father up would indicate that the first layer height may be off.

    My preferred way to calibrate the e steps and flow rate can be found here: https://forum.duet3d.com/topic/9999/horrible-print-results-help-needed/14



  • I had similar issues (and I’ve seen others here) and it was the thermistor settings.
    I don’t know if the online configuration was set wrong or it was “operator error” in each case but it had me chasing my tail.
    Perhaps if you post details of your config and thermistor type someone can rule this out.


 

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