How to prep stl files for dual extrusion?

[Fredini]

Hi all, 

Can anyone point me to any tutorials for prepping files for dual extrusion? I have two objects in a blender file that I want to have "stacked" together so they can be made as a single two color print. Currently, there's some overlap of the two objects, but it seems to me that I need to do a boolean difference to subtract the overlap from one. I gather I have to export both pieces as a separate STL file, right? But how do I export the two stl files so they align properly when imported to Replicator G? 

If anyone can point me to some tutorials for prepping files for a dual extruder it would be greatly appreciated!

thanks!

fred

[Cymon]

The process is still experimental and in it's infancy. I don't know if the new version of ReplicatorG will make it an easier process or not, but I've managed to make the new process work. I want to make a tutorial, but as far as I know it's be the only one and likely be out of date quickly.

[Andy]

I'm still sans replicator but have been experimenting with the process and checking gcode that skeinforge produces via pleasant 3d's gcode viewer.

In all my tests I assumed that the models could not occupy the same space in the 3d scene, so I've been careful to boolean off any geometry that intersects. 

From reading other messages in this group, i believe you want to make sure the two pieces of geom are already sitting above the origin plane, as it is difficult to move them around after importing in repG.

It also sounds like u want to have them properly scaled in your modeling software so they import into replicatorG at the size u would like to print.

In other words, you need to do all your resizing and aligning in the 3d package.

I don't have a lot of experience with blender, but there was a thread not too long ago where someone described how to adjust the unit settings in Blender to match what repG is expecting.

Hope that helps u get started!

-Andy

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[Chris Crewdson]

I just printed the first dual-extrusion thing I designed.

It's the red face part of this: http://www.thingiverse.com/thing:23007
The thing I used to align the parts was the circular peg. I centered that on the origin before exporting the part as an STL for both parts and it worked perfectly.

The other idea I have heard to to this is make some bounding exterior geometry (like a skirt) and base both parts on relative positioning inside the bounds. This would allow centering to happen in ReplicatorG.

As far as removing overlaps, it seems like the best would be using OpenSCAD to do something like an exclusive union. Basically part 1 would be:

difference{

    part1

    intersection{

        part1

        part2

    }

}

And part 2 would be:

difference{

    part2

    intersection{

        part1

        part2

    }

}

This would eliminate overlapping geometry.

[AKron]

I haven' done much with dual extrusion yet, but I made a logo in
SolidWorks that was OK. I made an extrusion for the plague, then made
a cut in it outlining the lettering of a different color. I then made
an extrusion of the lettering inside the cut in the plague. I
suppressed the lettering extrusion, and saved the part as plague.stl.
Next I suppressed the plague, unsuppressed the letting, and saved the
part as logo.stl. After that I did the ReplicatorG merge thing, and it
worked, although the black rubbed onto the white when it printed. I
also can't center each part on the platform, or I lose registration.
Like I said, I haven't done much with dual extrusion yet.

[shaunp]

Fred,

I have been using the OpenSCAD "difference" technique outlined by Chris with good success. Sometimes it is necessary to tidy up the original STL with Netfabb to get it working OK. I have been able to embed a text label stl file into a surrounding block with no problems on the subsequent dualstrusion print.

Shaun.

[Shawn]

I use blender but the process should be similar in other tools. I do it
like this:

1. build my model. Make sure all curves are converted to mesh when
getting set to go to the printer.
2. I select the parts I want in one color, then export those parts to an
STL file - parts1.stl (for example).
3. Then I select the parts I want in the second color and export those
to another STL file. parts2.stl.

NOTE: between steps 2 and 3 I am careful NOT to move anything around -
everything is properly positioned.

4. Open ReplicatorG.
5. Select GCODE -> Merge .stl for DualExstrusion
6. In the resulting dialog, I select my parts1.stl file for the left
extruder (swap the file as desired to match up with your color).
7. I then select parts2.stl for the right extruder.
8. Then I specify where I want the resulting gcode merged gcode file.
9. Click Merge.

This opens TWO gcode dialogs. Only one will be accessible initially.

10. Fill in the details for the first extruder (fill%, # shells, layer
height, filament size, etc.). Then generate that GCode
11. WAIT!! Do not do the second gcode until the first has fully
completed and written out the generated file. The progress bar window
may open behind your main window - regardless watch the console area of
RepG for when the gcode is done.
12. Fill in the details for the second extruder and generate the gcode.

When this process completes, you'll get the gcode for your parts2.stl
file, but you will also get the merged gcode file. The merged file will
be opened for your review.

Treat the merged Gcode the way you would any other gcode file. Export
it to S3G, transfer it to the printer and hit print.

That should do it. Have fun.

Shawn

On 12-07-13 06:53 PM, MJOnline wrote:
> Anyone know how to make the seperate STLs so they could be parts in
> Netfabb? Then they could be aligned somehow in Netfabb so proper sizing
> and alignement could be checked befor ethe 2 stls were created? A
> tutorial on this would be fantastic! Any help from Makerbot would be
> greatly appreciated please.

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[Shawn]

btw, I can't speak to how to use Netfabb for this... I've never used it
(yet). Sorry.

[DavidL]

 

I use Autodesk Inventor.   For what it's worth, I have noticed that it's just a simple matter of placing both parts relative to each other and relative to the coordinate system of the first sketch. The X=0 and Y=0 of the coordinate system will fall right in the center of the heating build platform.   Start with the Z=0 at the bottom of your part.

[Z LeHericy]

the problem is in the exporter within fusion, it exports with XYZ 0 at the center of the part. If you design from the base planes, "front" is the build platform, usually. My trick has been to load the parts up in openScad and move them there.

-Zeno LeHericy

//((=:Z:=))\\
INVENTIONS
Technologies
zinventions.com

On Fri, Aug 31, 2012 at 9:47 AM, Adam <able...@gmail.com> wrote:

Hi DavidL,

I'm also trying to use AutoDesk Inventor (Fusion version)... but I've got no idea how to get the pieces to show up at the base of the ReplicatorG Z plane... they always seem to end up 1/2 way through the Z plane.  For normal objects, this isnt a problem as you can adjust and center in ReplicatorG.  However, this is very frusterating when trying to do a dual-strusion print job.

Do you have any advice as to how to get an object aligned to the global XYZ axes in inventor/ inventor fusion ?

On Wednesday, July 18, 2012 1:53:31 AM UTC-4, DavidL wrote:

 

I use Autodesk Inventor.   For what it's worth, I have noticed that it's just a simple matter of placing both parts relative to each other and relative to the coordinate system of the first sketch. The X=0 and Y=0 of the coordinate system will fall right in the center of the heating build platform.   Start with the Z=0 at the bottom of your part.

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[Brant Fetter]

@DavidL, Interesting. 

I've made several dual material models, but still having trouble. I use AutoDesk AutoCAD or Fusion. I've been having some difficulty with ReplicatorG properly positioning the exported STL files. AutoCAD records a axis origin point for all exports, but ReplicatorG does not seem to use it. I attempted to print a dual extrusion model and thankfully the Replicator didn't hurt itself, it just wasn't able to extrude the second ABS color/material when the first material was present. 

It was quite obvious that the two files were not aligned by 1.5mm. So I looked at several different sets of STL files that were exported from AutoCAD where the origin was at the center or base of the model and found (as I have with single color models) that many of them do not 'land' at the middle of the platform, and matched sets in AutoCAD don't match up in ReplicatorG. So if anybody has experienced this, I'd love to know how you dealt with it systematically, (rather than editing the STL files and making them align that way, which can be very difficult with complex models). This may of course be some aspect of the export, so I'll report back if I figure this out.