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Strange gaps on layers when printing [SOLVED]

Posted: Sat Sep 10, 2016 5:06 pm
by WizarDru
Hi, all!

Just got my refurbished Robo-3D R1+ this week, and I'm quite happy with it (as an upgrade from my Printrbot Simple Metal). It worked right out of the box, with the exception of one of the screws on the filament holder on the extruder (the ones with the screws) popping off. I screwed it back on and the printer has worked fine, however...

While I've been dialing in the settings, I've discovered that my prints are all experiencing strange gaps on some levels and I'm not sure what setting to tweak. I've tried varying temperature (starting at 210 and down to 195) and changing some retraction settings, but it hasn't really gone away.

Basically, on some slices, you can see that it has some gaps when extruding. I've seen this behavior in both MatterControl and Simplify3D. The attachepicture should illustrate it.

Any suggestions as to what would cause this sort of behavior? I've tried the filament that came with the printer and some Boots Super Premium with the same result.

Image

Thanks!

Re: Strange gaps on layers when printing

Posted: Sun Sep 11, 2016 7:38 am
by CompoundCarl
Your picture isn't showing up, but I'm guessing you probably want to start with one of the links below
https://www.simplify3d.com/support/prin ... gh-plastic
https://www.simplify3d.com/support/prin ... top-layers

Re: Strange gaps on layers when printing

Posted: Sun Sep 11, 2016 11:58 am
by WizarDru
Carl, thanks for the reply.

I've used the print quality troubleshooter many times, but this seems different than most of the common problems I see listed there.

Here's another attempt to post the image:
Image

Alternately, here's a link to a copy on OneDrive:
https://1drv.ms/i/s!AlvEEhiM2ct7g1EXKNXDFaaNx-cA

Essentially the problem here (and ignore the messed up portion of the top of the print...that's just due to the print breaking free of the bed mid-print): are those odd gaps on the slices at random intervals. It's happened with multiple stl models, different filaments and different slicers. I'm worried it may be a problem with the printer, as I just got it and it's refurbished. But I'm working off the default assumption it's just a setting issue, as it's not consistent throughout the print.

Re: Strange gaps on layers when printing

Posted: Sun Sep 11, 2016 2:46 pm
by dorsai3d
If there aren't gaps showing up in the preview (which I've seen happen a lot when using bad STLs - like many things on Thingiverse), then I would suspect it's an issue with the printer in some way. This could be anything from the extruder slipping to partial clogs in the nozzle, or the hotend not maintaining temperature, or trying to print too fast for the printer/material.

Re: Strange gaps on layers when printing

Posted: Mon Sep 12, 2016 8:42 am
by CompoundCarl
Usually when I see random missing layers like that, it's due to an extruder problem

Re: Strange gaps on layers when printing

Posted: Mon Sep 12, 2016 2:17 pm
by WizarDru
I did a subsequent print of a dice chest that I've printed before and it was an improvment, but I'm seeing filament gaps and not just on the outer layers. I'm going to try printing at a higher temperature and see if that makes a difference. I've seen one suggestion that it may be some micro-clogging in the extruder and suggesting I should use an oiler and another suggestion a change to the infill overlap. I'll experiment more tonight.

Re: Strange gaps on layers when printing

Posted: Mon Sep 12, 2016 3:26 pm
by Derrick
Do you have a temperature monitor? or a way to do that? I've seen something similar to that when there is wiring issues necessitating a thermocouple/resist replacement, or a heater replacement. When the heater is disconnected (something as simple as the print heat moving around is jiggling/bending the wires causing a disconnect/reconnect somewhere), it gets too cool -> under/no extrusion = missing layers. I've also seen when the thermoresist dies, the heater reversely overheats, and there's huge degraded globs in certain layers.

Just a thought for you, as it's refurbished, and maybe that's why it was dumped by the original user, where the sporadic issue was not repeated during a hasty inspection. Or this could be totally not it.

Also, it's always a good idea to have extra nozzles on hand to replace it to rule out one of the most likely (in general) variable during troubleshooting.

Re: Strange gaps on layers when printing

Posted: Thu Sep 15, 2016 4:01 pm
by WizarDru
Thanks for the replies, all!

It turns out that it was an issue of micro-clogging in the hot-end. I had never heard of 'seasoning' before this, but several folks suggested that was the issue. I did that several times and the next print was much improved.

(Side note: as should be a surprise to absolutely no one, Simplify3D sliced to print several things dramatically faster than MatterControl for the exact same STL files on the same printer).