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Layer Shifts / Multi Material 50% Under Extrusion

Forums The Beast V1, V2 and Elevator 3D Printer Support Layer Shifts / Multi Material 50% Under Extrusion

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  • #1173
    mr.smr.s
    Member

    Hello,

    Yesterday a big layer shift of a couple cm happened that ruined my print. On closer inspection, I noticed that there had been many micro-shifts before that, and even the previous prints that I already had made exhibit them. Since I use my printer mostly for prototyping, for now, the micro-shifts are not enough to be a functional issue (but I would still like to fix them nonetheless).

    I checked the belts and they are tight, but not too much.

    I also increased the stepper motor power to max.

    I use a 0.8 mm nozzle, 0.25 layer height. I was wondering what print/travel speed settings I should use.

    Slicer is Simplify3D.

    The prints are big and take up almost all of the print bed and the material I use now and intend to use in the future too is TECH-G (https://taulman3d.com/techg-spec.html), if that makes any difference.

    What about closed loop stepper motors? Are there any drop in replacements for the motors that have that feature or does that require changes to the firmware/hardware?

    Thank you!

    #1335
    dandan
    Participant

    Skipped steps can occur for a variety of reasons. A picture of your failed print would reduce the possibilities a lot.

    Definitely reduce the power back to a normal level. Too much power can be a big issue for skipped steps.

    Check my sticky post in this forum on setting VREF first.

    Without seeing your print and based on what you’ve said. I’d be surprised if this isn’t one of the following:

    Micro skips : Is there ANY slop in your hotend assembly? If you were to grab the nozzle and wiggle it with your fingers, is there any play? Check delrin tension / eccentric nuts and make sure everything is nice and right.

    The big skip: .8mm nozzle, I’m wondering if any unwanted artefacts are entering the Z space? .8mm nozzle creates much bigger artefacts than .4mm making it much harder for the planar moving nozzle to jump over them, sometimes causing skips. Micro skips can also be observed if the nozzle is constantly “raking” over the surface. If this is the case, look for “z hop” in simplify3d and also consider “avoiding crossing perimeters “

    Again, a photo here would help heaps

    #1336
    mr.smr.s
    Member

    Here is the picture. I wrote cms but it’s actually a couple mms.

    I thought I read somewhere in one of your posts that the DRV8825 drivers you use are not going to cause skipped steps, just high temperature.

    I’ll go through the VREF procedure again.

    #1337
    dandan
    Participant

    I’m on my tiny iPhone SE so image is a bit hard to see but am I correct if it looks like the layer was shifting in one direction, then shifting back and so on? Do those shifts move in the SAME axis all the way around the print? Ie. if the move in Y direction, do they then move back in the Y direction? Or are they more random? A little bit Y forward, then X forward, then X back etc? Or is is hard to tell? What about the big one? Moving in a specific axis?

    Dan

    #1338
    dandan
    Participant

    The more I look at it , the more I’m thinking loose hotend assembly. Answers to those questions will help a lot.

    #1339
    mr.smr.s
    Member

    It’s hard to tell, but as I spin the part around there is no side that has the correct profile, so that leads me to believe it’s both in the X and Y axes.

    The hot end is firm, as is the whole assembly.

    #1340
    dandan
    Participant

    Ok. So a reasonable statement would “appears to be skipping in all directions”? Generally this is cause by backlash (play in either the x or y axis). Is it possible the bed is moving around and not the x or y axes?

    Also can you check the x and y carriage delrin wheels are they all making contact with the rail?

    Dan

    #1341
    dandan
    Participant

    Also. A simple 20x20x20 test cube will clarify as you can usually get the whole cube in detail in one photo.

    Just follow those ridges around the object. Pick any ridge. Is the one ridge (for example) shifted in the same axis all the way around. Ie (Y+2mm)?

    #1342
    mr.smr.s
    Member

    Yes, it appears to be skipping in all directions. All wheels are making good contact.

    Before I go and try printing more stuff, can you suggest some good print and travel speed settings?

    #1343
    dandan
    Participant

    The defaults in the simplify3d profiles are safe. Also just to double check. Have you calibrated the extrusion length?

    Dan

    #1344
    mr.smr.s
    Member

    No. How do I do that?

    #1345
    dandan
    Participant

    Remove the Bowden tube from your pre heated hotend. Cut the filament off flush with the tube. Use the LCD to extrude 100mm and measure the length of filament which comes out. Post the results.

    Dan

    #1346
    dandan
    Participant

    Also. Please let me know. Is there any chance your part delaminated from the bed during printing?

    Dan

    #1347
    mr.smr.s
    Member

    The parts stick to the bed. I use Nano Polymer adhesive and it works perfectly with that material.

    Interesting thing, the extruder test came out very off. I measure exactly 50 mm when commanding 100 mm out.

    However, my prints don’t show under-extrusion, so I’m not sure what to make of that. Should I leave it as is?

    #1348
    dandan
    Participant

    Well you need to work this one out first – its a major problem. Likely not causing your layer shift issues though.

    Could you please remove both your extruder stepper drivers from the circuit board and take a photo of the jumpers underneath? I have a feeling the micro stepping isn’t correct.

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