Part Design / Mesh issue - 3D print time longer than normal

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Jred
Posts: 4
Joined: Mon Oct 07, 2019 9:08 am

Part Design / Mesh issue - 3D print time longer than normal

Postby Jred » Mon Oct 07, 2019 9:45 am

Hi everyone,

First of all, a big thank you to the whole FREECAD community.
Your help is very valuable to all of us: new users of FREECAD and aspiring designer.

On my side, I am facing some issue with the mesh of a design that I submitted to a fablab for 3D printing.
The guy from the fablab mentioned that there should be some issue, since the time for printing is about 13hrs and it is twice longer than it should be for this type of design.

I have created the following design (cf doc attached), and it seems to be without error.
I have then exporting to mesh by:
> selecting the final object created (Cut of 2 shapes); and
> exporting to STL via file > Export... > Save As "*.stl"

My mesh seems to be OK as per the print screen attached: It reflects well the features and constraints of the design.

Therefore I wonder what could be causing this extension of work to the printer?
> Could there be a wrong process in the design that provide unnecessary work or misinterpretation for the printer?
> Or is it a problem with the mesh generation?

Since, I have also submitted a design a couple of days ago to the fablab where the time of printing was 36hrs and was impossible according to the same manager, I strongly believe that I am doing something wrong either in my design, or with the mesh.

Thank you all for your help!

Spec info:
OS: macOS 10.14
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.16131 (Git)
Build type: Release
Branch: (HEAD detached at 0.18.3)
Hash: 3129ae4296e40ed20e7b3d460b86e6969acbe1c3
Python version: 3.6.7
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/UnitedStates (en_US)
Attachments
Screenshot 2019-10-07 at 11.31.34.png
Screenshot 2019-10-07 at 11.31.34.png (111.17 KiB) Viewed 237 times
CELLSHIFT v5.FCStd
(197.24 KiB) Downloaded 12 times
wmayer
Site Admin
Posts: 14989
Joined: Thu Feb 19, 2009 10:32 am

Re: Part Design / Mesh issue - 3D print time longer than normal

Postby wmayer » Mon Oct 07, 2019 10:12 am

Important for the export is that you only select the object called "Cut" and nothing else. For me the mesh has: 43210 faces, 64815 edges and 21149 points

After exporting the mesh you can import it again and use the evaluation functions of the Mesh workbench. For me the tools don't find any errors so that the mesh should be OK.
M4x
Posts: 35
Joined: Sat Mar 11, 2017 9:23 am
Location: Norderstedt / Germany

Re: Part Design / Mesh issue - 3D print time longer than normal

Postby M4x » Mon Oct 07, 2019 11:29 am

Did you check this thread?
NormandC wrote: Most Commonly Asked Questions

Q. I exported my model to STL or DXF but all the holes are filled up and fillets are missing.
A. Don't select All or use Ctrl + A to export for 3D printing. You typically only need to select the last object at the bottom of the Model tree, or in the case of a PartDesign Body, select the Body itself.
https://forum.freecadweb.org/viewtopic.php?f=3&t=2264
kisolre
Posts: 1360
Joined: Wed Nov 21, 2018 1:13 pm

Re: Part Design / Mesh issue - 3D print time longer than normal

Postby kisolre » Mon Oct 07, 2019 12:06 pm

Here is what Slic3r gives with average settings:
.
CellShiftSliced.JPG
CellShiftSliced.JPG (148.86 KiB) Viewed 214 times
.
123 MB G-code file !!!
On my slow printer it will take 17.5 h and with those 0.5mm holes I am pretty sure it will fail miserably. Those are a lot of small extrusions and small travel moves, probably a lot of retractions also.
User avatar
pl7i92LCNC
Posts: 209
Joined: Tue Mar 12, 2019 3:03 pm
Location: RLP DE

Re: Part Design / Mesh issue - 3D print time longer than normal

Postby pl7i92LCNC » Mon Oct 07, 2019 1:40 pm

you need a real good printer to get this done
on fine print cura .1 i got 28hr
on a standard i got 12hr but this will not give you the part yu want on that holesize
M4x
Posts: 35
Joined: Sat Mar 11, 2017 9:23 am
Location: Norderstedt / Germany

Re: Part Design / Mesh issue - 3D print time longer than normal

Postby M4x » Mon Oct 07, 2019 6:41 pm

I've got 7 hours. I've used Simplify3D, 0,2 mm layer height, 20% infill (fast honeycomb), 80 mm/s default printing speed. I assume that it would take something like 9-10 hours in real time.
Jred
Posts: 4
Joined: Mon Oct 07, 2019 9:08 am

Re: Part Design / Mesh issue - 3D print time longer than normal

Postby Jred » Tue Oct 08, 2019 2:51 pm

wmayer wrote:
Mon Oct 07, 2019 10:12 am
Important for the export is that you only select the object called "Cut" and nothing else. For me the mesh has: 43210 faces, 64815 edges and 21149 points

After exporting the mesh you can import it again and use the evaluation functions of the Mesh workbench. For me the tools don't find any errors so that the mesh should be OK.
Thanks wmayer.

Yep I did select only the Cut object.
Good tip on reimporting the mesh, I'll try that
Jred
Posts: 4
Joined: Mon Oct 07, 2019 9:08 am

Re: Part Design / Mesh issue - 3D print time longer than normal

Postby Jred » Tue Oct 08, 2019 2:55 pm

kisolre wrote:
Mon Oct 07, 2019 12:06 pm
Here is what Slic3r gives with average settings:
.
CellShiftSliced.JPG
.
123 MB G-code file !!!
On my slow printer it will take 17.5 h and with those 0.5mm holes I am pretty sure it will fail miserably. Those are a lot of small extrusions and small travel moves, probably a lot of retractions also.
I don't have the benchmark on typical size for G-code... what's the standard/average size?
That's one more reason to think that there is an issue in my design.... :/

Regarding the printer, the fablab has an WITBOX2 which has a resolution of up to 20 microns.
I suppose it should be enough in my case?
Jred
Posts: 4
Joined: Mon Oct 07, 2019 9:08 am

Re: Part Design / Mesh issue - 3D print time longer than normal

Postby Jred » Tue Oct 08, 2019 2:57 pm

M4x wrote:
Mon Oct 07, 2019 6:41 pm
I've got 7 hours. I've used Simplify3D, 0,2 mm layer height, 20% infill (fast honeycomb), 80 mm/s default printing speed. I assume that it would take something like 9-10 hours in real time.
Thanks for the feedback M4x !
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DeepSOIC
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Location: Saint-Petersburg, Russia

Re: Part Design / Mesh issue - 3D print time longer than normal

Postby DeepSOIC » Tue Oct 08, 2019 3:26 pm

A good way to have a grid of holes is to expose some rectilinear infill. Sure, they won't be circles anymore, and not watertight between each other, but it will print FAST and reliable. Getting hole size accurate this way is tricky, but so it is if you just try straight out printing it.
I have no idea how to explain this to fablab.

Also, consider SLA print. May be substantially more expensive, but with a lot better quality.