Z Lift issue with Support enabled



  • I have been printing without support enabled, and so far so good. BUT, when i enabled MatterSlice to generate support the head keeps ramming into the model. Happening on first layer. I raised the z lift to 2mm and minimum travel to 4mm, still it keeps ramming into my model. The model is large, round and fills the bed of my RostockMax. The actual model at the bed height is smaller and gets larger with overhangs about 15mm up. So, on the first layer the support structures are close to the outer edges of the bed. What i noticed is, when printing the model the Z lifts fine, but, it Does NOT lift at all, that i could see, when printing the Support material,

    So, it prints the skirt around the support fine, then prints the base for the model, fine, but, when it goes to print the support base and it crosses the model base, it rams into it, knocking it off the bed. It isn't lifting the nozzle at all when it travels to print the support material.

    That is, at least, what i am observing. i am using 1.5.3 of MatterControl. I see no separate setting for zlift for Support material. If my observation is correct, i would hope this will be an easy thing to fix. It appears the ZLift routine is not being called when printing support. Hopefully this can be fixed quickly



  • Z lift only happens during retractions. Retractions are not normally done when moving between sections of support material, since it doesn't really matter if the support material has strings through it. If part of the actual object is in the way, though, I can see why you would want it. It causes the head to run into the part, and also leaves strings connecting the part to the support.

    Unfortunately, there's no way around this at the moment. I'll talk to the developers and see if we can improve this behavior, though.


  • MatterHackers

    Ideally, you shouldn't need Z lift. Because it's common for Deltas to not be perfectly leveled, especially when out to the edges of the bed, Z lift can help. We likely won't be adding Z lift to support material for a few reasons, however you should be able to level your machine better so that your head doesn't run into the part.

    Have you tried the 13-point software leveling in MatterControl?



  • I was using the 13 point leveling. I am also printing with PETG, which does ooze more then ABS or PLA. The part i am having problem with has a circular base, where the diameter of the object at the bed level is smaller. There are over-hangs about 15 mm up that overhang to the outside - so the support is outside the base. MatterSlicer prints the skirt, then prints the base of the object, when it is finished with the object base it goes to print the base of the support on the outside. When it finished the object base it travels all the way to the other side of the bed - across the base of the object, to print the support on the outside. It seems by the time it gets to the other side the PETG has oozed out enough when it runs across the object it catches on it, and pulls it up - can't really tell if the nozzle is contacting it, or the oozed material is swipping it and catching onto it and pulling it up. As it is, i am using glue stick on heated glass, and the parts hold quite well to the bed. When it's done i have to tap it with a wrench to free them, so i don't think i can or want to glue them down any harder to the glass.

    I've printed the same parts with Slic3r and they printed fine. I've never had any problems like this, so i may need to go back to Slic3r and getting the repetier firmware bed leveling to work.

    One work around that did work for now was I modeled in the support so it is part of the object and turn off support generation in MatterSlice. That works, but, my plan was to add a second head and use a pva support material. I can see that being a problem with MatterSlice - Unless I model in the support like i am doing now, and print it as as a single object with 2 materials. Now that i thought about it, that may work. But, I don't see why it cannot be an option to allow for Z lift while printing support - Slic3r seems to do that and so i never had this problem before.




  • We've filed a bug report on this issue. You can track the progress on Github.



  • @unltdsoul said:

    MatterSlicer prints the skirt, then prints the base of the object, when it is finished with the object base it goes to print the base of the support on the outside. When it finished the object base it travels all the way to the other side of the bed - across the base of the object, to print the support on the outside. It seems by the time it gets to the other side the PETG has oozed out enough when it runs across the object it catches on it, and pulls it up - can't really tell if the nozzle is contacting it, or the oozed material is swipping it and catching onto it and pulling it up. As it is, i am using glue stick on heated glass, and the parts hold quite well to the bed. When it's done i have to tap it with a wrench to free them, so i don't think i can or want to glue them down any harder to the glass.
    I've printed the same parts with Slic3r and they printed fine. I've never had any problems like this, so i may need to go back to Slic3r and getting the repetier firmware bed leveling to work.


    I have the EXACT same issue, and this problem has destroyed several 20+ hours prints. Im going to have to switch slicers if its not fixed soon. The issue is not with bed leveling, its that sometimes the nozzle will snag onto parts when traveling across them, and z-lift eliminates this ever happening (not to mention it causes ugly streaks on top layers even if your level is spot on). Its critical to z-lift when printing support structures, or at least have an option to "Never cross printed areas when moving between islands."



  • Update: This issue has been fixed in the latest code. It will be available in the next version of MC (1.6).


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