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Posted · Z-Seam Troubles

Hello,

 

I've been working on some relatively thin trim clips and the position of the Z-Seam has been causing the model to "collapse" where the seam is.  Essentially the nozzle pauses a hair where the seam is which results in the existing print sticking to it a little.  As this area is so thin, when the nozzle begins to move again it takes a tiny bit of this edge with it, causing a deformation.

 

So far I've done a lot of fiddling with the Z-Seam, and it's gotten a little better, but ideally I would place it in the middle of the rear wall as you can't see that area anyway.  Is there a way to do this or will Cura always use a corner if there is one?  So far I have been unable to place it in the middle of a flat surface.

 

My second idea is to add a small bump/line in the center of the back of the model so that Cura will place the seam there instead.  It's probably the easiest solution, but for the sake of future models and just solving the issue itself, it'd be nice to be able to fix this in Cura if it's possible.

 

Curious if anyone has any ideas.  This one has been driving me nuts.

 

 

In the photo, the deformation is on the top left corner of the parts.  When printing, this is actually the bottom right corner - where the seam is.  This issue persists across different hot ends, printers, and materials.

 

Thanks.

20210518_090936.jpg

CE3PRO_Bolt Hole Cover Clip v3_petg.3mf

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    Posted · Z-Seam Troubles

    Thanks @Torgeir for the response.

     

    I actually started with the parts oriented that way (flat on the build surface) originally, but the issue is that the tabs are too weak when printed in this orientation - they're functional, but not idiot proof, and since this is a product I am selling I can't take chances on that :).

     

    I literally just fired up a print based on my second idea in the original post, so we'll see how it turns out here in about an hour.  It allows me to have the seam in the middle like I wanted, although I'm still curious if there's a way to do this in Cura alone.

     

    Attached is a screenshot of the updated model showing the new seam location.

    Screenshot (297).png

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    Posted · Z-Seam Troubles

    For strength you want those clips sideways like in the picture.

     

    For beauty and print speed and saving filament (and so you need zero support) you want to print the flat side to the print bed.

     

    You can do both.  Separate those clips as separate prints and glue them together, or screw them together.  You could embed a nut into the circular part as it prints (pause at layer) or you could just have a hole that is the right size so that a metal screw self taps into the round part (that's what I'd do).

     

    Also I'd make those clips something much tougher (less brittle) than PLA.  As a minimum I'd use tough PLA but more likely I'd use Nylon.  Yes it's much harder to print but evenually you would learn to print those clips perfectly every time and you can print 20 at a time in Nylon then switch to PLA.

     

    Nylon is super tough - you can drive over those clips with a car no problem (if they are nylon).

     

    Printing on edge like that will greatly reduce quality as the round part will wobble up until the moment the clips are connected to the support towers.  So quality won't be so good on the 40 layers up to the clips and then suddenly it will get good again and it will just look a little off.

     

    Better to make the design super good if you are printing lots of these (more than 10).

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    Posted · Z-Seam Troubles

    Hi there,

     

    Sure, did not think about the locking tabs and sure agree about the orientation for the strength issue.

    However, if you go for the nylon -you can print with the flat part down, but the print temperature is important here.

    Actually I made a bearing in nylon for our dishwasher's upper water spreader (propeller), as the old one cracked after 33 years of use!  When I made the first one, I'd selected to lo temperature (235 deg. C.). At this temperature the tabs snapped easily off, they was not properly bounded to the main body. So I experimented a little and found 255 deg. C. to be the selection for me, -I could not break off the tabs -no way!

    This one have been in operation for almost two years now, with no issue, hot water here is 75 deg. C.!

     

    Sure you'll need to cover up your printer to keep the temperature as close to the "bed" as possible. I was able to get 47 deg. C. inside the printer with bed at 70 deg C.  This was an UM2E+ printer. (Also used the shield draft function in Cura.)

    Nylon might make some stringing, but can be controlled with the right retraction setting..

     

    Anyway, whatever method you're using -good luck.

     

    Regards

    Torgeir

     

     

     

     

     

     

     

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    Posted · Z-Seam Troubles

    Thanks again for the response Torgeir.  I was just headed back here to report that I have the issue (mostly) solved.

     

    After about five combinations of outer wall first vs second, single wall with infill vs all walls, and fan combinations, I've got things to a fairly acceptable level (see attached photo; left is original, right is new).  Up until recently I've been using PETG for these parts, but unfortunately it's not quite holding up to the temps seen inside a vehicle when under load (ie. the tabs lose some tension).  Now I'm switching over to ASA and the seam issue became much worse as seen in my first post.

     

    Turns out that via the combination of "moving" the Z-Seam, using a single wall printed first, line infill with connected paths, and adding 20% layer cooling fan I have drastically improved finish quality.  I still need to do some destructive testing to ensure the parts are not notably weaker due to the layer cooling fan, but I have a feeling it's going to be fine.  There is still some slight deformation at the very bottom of the part, and I believe this is due to the Z-Seam still being on the edge here (I can't add the center bump in this area due to application constraints).

     

    Addressing your nylon suggestion, yes nylon is a great filament and I've had good luck with it for a number of things.  Unfortunately, I need to be able to post-process these parts with sanding, painting, etc. which nylon doesn't lend itself well to as far as I know.  I think ASA is going to work out pretty well here, but of course time will tell.

     

     

     

    Pre-Post Edit :).

     

    Whoops, almost missed your response gr5.

     

    Your idea of printing them in two pieces for strength and looks, and then attaching them somehow is a good one - funny enough I contemplated that two months ago 🙂 (I've been working on these things for too long...).  I ended up dismissing it because I figured it would be more work than it's worth, but perhaps I'll have to revisit it if I can't get these other methods working consistently.

     

    And interesting point about the part being "wobbly", I hadn't thought of that.  Now that you've mentioned it, I do notice a small horizontal line at the very bottom of where the tabs begin - perhaps that's in part thanks to the wobble.  Huh, neat.

     

    Going back to nylon again, it really is great stuff.  I was seriously impressed when I first picked some up and couldn't break a strand by pulling on it.  I've used it for gears, bushings, etc. but as I mentioned above (in what is becoming a rather long post, criminy...) for this application I don't think it will work.

     

    Anyway, I think that wraps this up for now, unless anyone else has some more ideas on how to further improve finish quality.  I do have some other clips to do still so it'd be nice if the thread doesn't get closed just yet, or is that even possible here?

     

    Thanks again for the suggestions.

    20210518_150853.jpg

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    Posted · Z-Seam Troubles

    If you are painting these things black - know that you can buy "natural" nylon filament (it's probably the most common nylon filament option) and dye it.  It comes out looking amazing when you dye it.  It shocks me every damn time.  Nylon is good at absorbing water or oil both so you can use almost any kind of paint supposedly but dye is so much easier.

     

    https://www.instructables.com/How-to-Dye-Your-Nylon-3D-Prints/

     

    I always skip the soaking step and it comes out just fine.  Better than just fine.  I have only done black dye and it's... amazing.  I mix the dye with boiling hot water in a glass container and dip the part for 6 minutes.

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    Posted · Z-Seam Troubles

    Interesting, I've honestly never looked into the dying process - I figured they would look more liked dyed fabric or something, but the parts in that link you shared look great.  Natural nylon is what I already use because for those parts I generally don't care about the color, although now you've got me intrigued.  It would also solve the issue of matching some of the more specific vehicles interior colors, such as red, charcoal, etc. that are hard to find filament the right shade for.

     

    The primary concern I have is the UV resistance of the dyes.  Cost-wise it would work out to be almost equal with ASA, with perhaps a little bit more being spent with nylon for the dyes.  I'm still kinda bummed that PETG doesn't quite withstand high enough temps, because the layer adhesion is superb.  Nylon of course would solve both of those issues, although again, it's the post-processing and dye's long term UV resistance that has me curious.

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    Posted · Z-Seam Troubles

    Well Nylon is much more flexible and that can be a problem in certain situations.  When buying Rit dye it shouldn't cost more than $2 to $4 per bottle.  I've seen it much more expensive so shop around a little.

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    Posted · Z-Seam Troubles

    Yeah, that's about what I was seeing it go for.  Cost realistically won't be much of a hurdle, it's the UV resistance over time that I'm really wondering about.

     

    So far I haven't found much anything except some articles about increasing the SPF of fabric for better sun protection of the wearer, not necessarily the pigment itself.  As long as it can last a few years without fading I'm good, but so far I haven't come across anything to say so or otherwise.  It's also inside a car, so the glass and shadows will block some amount of UV, though a fair amount still gets through.  Eh, I'll keep scouring the web I suppose :).

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    Posted · Z-Seam Troubles
    On 5/19/2021 at 4:59 PM, Benjamin4456 said:

      It's also inside a car,

    What!?  In the passenber compartment??  That can get HOT.  Hot enough to melt PLA.  So yeah PETG, Nylon, nGen can handle the heat.  No idea about UV but I don't think much UV gets through the glass?  I don't know.

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    Posted · Z-Seam Troubles

    Hot indeed.  At first I tried a couple PLA parts just for kicks and sure enough after not even a day they had practically fallen out of their install locations.  Now the benchmark I'm using is 150F to consider it "suitable".  PETG holds up fairly well, although parts under stress deform slightly in high heat (tabs on clips and whatnot).  ASA does well although has worse layer adhesion.  Haven't looked into nGen yet.

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    Posted · Z-Seam Troubles

    Check out this active thread's discussion about how to fix layer adhesion for ASA: 

     

     

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