Messy print

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Riverwood3D
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Posts: 5
Joined: Mon May 07, 2018 2:38 pm

Messy print

Postby Riverwood3D » Tue May 08, 2018 1:39 pm

I'm trying to design keychains with my students but they are not filling in properly. I have tried adjusting speed, extruder, everything. Any suggestions?
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gchristopher
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Joined: Mon Dec 08, 2014 2:09 am

Re: Messy print

Postby gchristopher » Tue May 08, 2018 7:13 pm

Hi! What slicer software are you using, and with what settings?

It looks like your first layer height is okay, or maybe just a bit high? That doesn't look like a mechanical problem to me.

My first guess is that the slicing software is having a hard time with the small gaps and the gcode it's producing doesn't cover those places that should be solid.

Depending on the software you're using, you might have some different options for what infill pattern to use. That looks like it's drawing 3-ish concentric shells around each perimeter, but failing to fill in the area between the shells. Different slicers approach the problem of the gap between fill and overlap differently. Some slicers have options for how much "overlap" there should be between the fill and perimeter, too.

Riverwood3D
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Joined: Mon May 07, 2018 2:38 pm

Re: Messy print

Postby Riverwood3D » Tue May 08, 2018 7:39 pm

I'm using the slicer in Matter Control. I'm new to printing and that was the one in the instructions.

The fill is done with triangles, should I try lines? I did various densities and it didn't seem to make a difference.

I believe the first layer was 3mm. Should I cut it back?

Any suggestions (even on a different software) are much appreciated!

Riverwood3D
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Posts: 5
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Re: Messy print

Postby Riverwood3D » Tue May 08, 2018 7:39 pm

Oh, and using standard setting with 2mm layers.

IMBoring25
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Re: Messy print

Postby IMBoring25 » Tue May 08, 2018 10:29 pm

1) He's talking about the accuracy of the first-layer height, not its absolute value in mm. That comment was about the quality of your leveling, not your slicer settings.

2) In case it becomes relevant in the future, typical layer heights are on the order of 0.2 and 0.3 mm. Whole-number mm layer heights would produce very blocky prints if you could and you usually start getting quality issues as you try to go to layer heights more than about 80% of nozzle diameter.

3) MC has several slicers in it that you can choose or you can download a standalone version with more configuration options. Parts with text are quite tricky because they have a lot of places where extrusions necessarily move closer together and farther apart. Getting the little triangles filled in without overextruding is quite an acid test for your slicer and configuration. I typically use the standalone version of Slic3r and it has a lot of settings that would be relevant to tuning that... Percent overlap, pressure advance, etc.

Riverwood3D
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Posts: 5
Joined: Mon May 07, 2018 2:38 pm

Re: Messy print

Postby Riverwood3D » Wed May 09, 2018 4:13 pm

Didn't even realize what I printed, I was in a rush. The total keychain is 3mm so obviously the layers are not. Lol

If I try Slic3r, what modifications would you recommend I try? I've just been printing for a few weeks and want to produce the best quality for my students' work.

P

gchristopher
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Re: Messy print

Postby gchristopher » Thu May 10, 2018 4:42 am

This is going to sound terrible, but the best advice I have is to be willing to try lots of different software settings and not get frustrated. But I've never had "don't get frustrated" be useful advice for me...

Per mhackney's advice, I've been using the Prusa version of Slic3r lately and been mostly happy with the results. (Plus the 3d printed fishing reels he makes and sells are have flawless first layer quality.) You can get it here:

https://github.com/prusa3d/Slic3r/releases

In your situation, I think my plan would be to first make the smallest print I can that has those first layer infill problems. If you can make a small model that reliably gets the problems to happen quickly, then you can use that to test ideas with less time involved. (Of course, we're still talking about 3d printing taking over your life for a while, but hopefully that's part of the appeal.)

There's a few things going on there, like:

- The long straight gap along the whole top and bottom of the print. (That's pretty bad, most slicers should do better than that.)
- The irregularly shaped gaps like around and between "ER".
- Maybe that round gap inside the first O, but I think that one might be a very similar artifact to the top one.
- The really tiny gap between the hole and the corner. (For most slicers, that might be a hard one to always fix.)

Then, as IMBoring25 said, you're going to have quite a few options to play with, depending on which slicer you're using. The big long gaps look to me like the slicer just didn't plan good enough lines to cover the whole area, but I can't rule out under-extrusion (extrusion rate) or layer height issues just from one picture. For little gaps in odd places, there's a lot of potential culprits like retraction or bed adhesion. e.g. If your retraction left a little bit of plastic behind while it was moving the print head to fill in a gap, it might not extrude enough right away when it gets there, or the plastic might not instantly, perfectly adhere, and it will drag a bit away from where it should be when it starts printing the infill.

One beginner approach (which I use frequently) is to calibrate your printer to start just a little low for the first print, so it's forced to squish the plastic down a little bit lower than perfectly 0.2 or 0.25 mm or whatever the first layer height is set to. When it starts printing, you'll see the plastic look flattened, and you have to be careful that you're not too far down.

This creates a little bit of "elephant foot" around the edges of the print that you might have to trim off later, but helps to guarantee that the entire first layer makes contact with the print bed and you end up with a smooth, line-free first layer. Some slicers (like the prusa slic3r) even include an "elephant foot compensation" setting for this.

Riverwood3D
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Posts: 5
Joined: Mon May 07, 2018 2:38 pm

Re: Messy print

Postby Riverwood3D » Fri May 11, 2018 5:48 am

Thanks! I'll try a new slicer first and go from there!!!


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