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How to design for a dual extruder (2 color) 3D print?

19 REPLIES 19
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Message 1 of 20
sprior913
12864 Views, 19 Replies

How to design for a dual extruder (2 color) 3D print?

From what I've learned, to create a 2 color model to 3D print you create two STL files, one for each color.  Is there any special technique to creating a model in Fusion 360 that helps with this?

19 REPLIES 19
Message 2 of 20
sickforska
in reply to: sprior913

There is a feature request for the AMF filetype. You may be able to find some other software with AMF support and export from Fusion 360 to that software to your slicer, but then you would also need a slicer with support for reading AMF filetypes. It doesn't seem like it would be difficult at all for them to include it, so enough requests might make it will happen sooner.

Message 3 of 20
sprior913
in reply to: sickforska

It doesn't look like my chosen slicer Simplify3d supports the AMF file format, it seems that seperate STL files is the current way to go.  That sounds like it requires maybe exporting all objects/bodies with a given material setting to a single STL file and then doing it again for the other.

Message 4 of 20
sprior913
in reply to: sprior913

The dual extruder upgrade for my printer should be arriving in a couple of weeks and I'm still looking for an answer on this topic.  It seems that my chosen slicer program (Simplify3D) can take stl files for each color and print them together in a dual extruder printer.  So what I'm interested in is what's the technique to design things in Fusion 360 and keep track of two different colors so that I can export a STL file for each?

 

In general does Fusion 360 have any concepts which can help with dual extruder models?

Message 5 of 20
deyop
in reply to: sprior913

I'd like to help you develop a strategy for this but need a bit more detail on how the two colors would be utilized in the object.  Do you have any examples (images would help)  that would indicate the results you would like to get?  

Message 6 of 20
sprior913
in reply to: deyop

I was thinking in general terms and didn't have a specific project in mind, but just for the sake of the discussion how about a cube of one color trapped inside a wire frame of a cube in a different color - that sounds like a good test object.  If you can think of something different that's perfectly fine.  Another neat example would be a name plate where the plate is one color and the text a different color - that would be a good example that doesn't need any support and nothing jiggles around.

Message 7 of 20
deyop
in reply to: sprior913

You can create separate STL files for any body or component in the browser.  Here is a blog that will show you all the details on creating the STL files that you should be able to take into your slicer.  However as mentioned previously by sickforska there is no method for transferring the color or material assignments currently.  STL files do not support color just the geometry.  AMF may be the standard that will allow that to happen in the future.  Some systems will read VRML colors but that is not a broadly used standard either.  

 

Autodesk hopes to find solutions for this problem as part of our Spark initiative.  For now I am afraid we are not keeping up with the capability of the printers options available.

 

In discussing your issue with another team member I learned that there are filament materials available that are water soluble.  This means it would be possible to print supports in a material that could be removed by soaking in water.  That sounded like a neat application of the dual head printer.

 

Let's keep discussing as you get your new printer heads and see how we can get you the most out of them.

 

Thanks  

 

Paul

 

DualSTL.jpg

Message 8 of 20
sprior913
in reply to: deyop

I don't care if Fusion 360 keeps track of the actual colors - that's ultimately decided by me the moment I put the filemants in the printer.  All I need is to be able to export a pair of STL files with all the items of each color grouped together.  At least that's my current understanding.

 

In my case the supports are generated by the slicer program itself so the usecases of generating the support in a dissolvable material and using a thicker nozzle to speed up infill come "for free" without any support from my design program.  Though if I did use Meshmixer to generate the supports and then export that STL to my slicer I suppose it would need to be exported as a pair of STL files.  BTW in addition to the water solulable filement which seems to be new and untested there is also support which can be dissolved in Limonene which is supposed to be relatively cheap, safe, and effective, haven't tried it myself yet.

 

The problem with Spark is the same as all the other standards out there - everyone wants to own the standard so you end up with lots of them.

Message 9 of 20
sickforska
in reply to: sprior913

The only way I found so far is to put all of your bodies into components by their color. You can then save each component as an stl. The problem for me is lining the files up in the slicer. Your slicer seems to do be able to align them automatically according to this page http://www.simplify3d.com/support/tutorials/printing-with-multiple-extruders/. It doesn't appear to be based on the bounding box so you may be in luck.

I figured out that you can assign appearances to your different colors and then use the "select applied to" option in the appearance panel, but once you close that panel the selection disappears. I couldn't find a way to group the bodies selected when that panel is active though.
Message 10 of 20
lkeppner
in reply to: sickforska

I am also using Simplify and have found that it is superior in many respects to the free programs. I still find that I use Cura or Slic3r sometimes to get exactly the effect I am looking for (i.e. infill patterns in Simplify are limited). However, I have just upgraded my printer (Airwolf HD2x) to dual extruders and I am having alignment problems from Fusion360 STL. I am using the technique you discussed earlier of combining bodies as components and exporting as STL's. Then I can bring both STL files into the slicer and assign different extruders to each STL.

 

My problem starts when trying to align the STL's. Both Simplify and Cura provide auto alignment with a simple keystroke. However, there is the exact same misalignment in the XY plane between the two bodies regardless of which slicer I use. I would think that the STL's would reference the same coordinate system with true 0,0,0. If so, this could not happen. I have even "moved" the bodies in relation to each other in Fusion just to find the EXACT same misalignment in the STL's. I am now thinking that this is due to some "adjusting" that is happening automatically in MeshMixer. Perhaps, for example, MeshMixer is adjusting the origin for each body to "force" some kind of bed alignment???

 

For reference, I have printed models with my dual extruder with fantastic results. However, these have been gcode (or AMF) files that I have gotten from others. I know that several of the sample models were produced with Solidworks and they appear to align perfectly. I am still trying to find the source of the error: Fusion or Meshmixer. I wondered what would happen if I export the raw STL without MeshMixer and "repair" the model through the utility in Simplify only.  Haven't tried that yet (tonight's project).

 

Anybody elses thoughts or experience would be greatly appreciated.

Message 11 of 20
lkeppner
in reply to: sprior913

Btw, the material that can be dissolved with Limonene is HIPS (High Impact PolyStyrene). It prints within compatible temperatures with ABS. I have found that it doesn't adhere exceptionally strongly to ABS so it peels away pretty easily when used as support material. I then drop the piece into my heated ultrasonic cleaner filled with Limonene and very quickly any remaining support material is gone! Your part just smells like citrus for a few days!!!

 

Btw, you could just as easily reverse the materials and dissolve the support (built in ABS) with Acetone. It doesn't affect HIPS! It is nice to be able to selectively decide which material you want your final part to be.

Message 12 of 20
TheCADWhisperer
in reply to: sprior913


@sprior913 wrote:

.....  BTW in addition to the water solulable filement which seems to be new and untested .....


Might be "new and untested" for your printer, but we have printed parts with water soluble supports for at least 10 yrs on our machines.

Message 13 of 20
deyop
in reply to: lkeppner

Thanks for the background on two head printing.  Would it be possible to share the two STL files that are misaligning or an example set with the original F3D?  I will try to determine the cause of the issue.  I tested with simple primitives and couldn't reproduce the problem when opening in Meshmixer.  It would be good to test with the parts you have.  You could zip them and attach to the posting.  Sorry for the problem.  We would like to get it fixed.

 

Thanks

 

Paul

Message 14 of 20
lkeppner
in reply to: deyop

Thank you for the response. I have zipped several files in this attachment because I am zeroing in on WHEN the problem occurs. I have included the F3D file as well as several exported STL's from this file. It is relatively simple. I created text as a sketch, extruded it into a component so all bodies would stay together. I then created an ellipse as a second sketch, and extruded that to different height. I then created a solid cylinder and subtracted it from the ellipse. Then using the ellipse as the target and the text component as a tool I performed a cut - creating a component to keep all the new bodies together and applied a small fillet to the top edge.

 

At this point I have two components that align and fit together. Exporting each as an STL works perfectly! They realign in my slicing software.

 

HERE IS THE PROBLEM: I then moved the text component in the original drawing. I also removed one of the bodies from within the component to prove that the new STL was indeed updating. When I exported the new "Front" STL (raw 3 in the file), I expected to see the "offset" when recombined in the slicing software. Lo and behold, the two components realing EXACTLY as the original.

 

I then tried another experiment... I moved a single body within the "Front" component then exported the STL again (raw 4 in the file). When recombined within the slicing software, the text component realigned exactly as before - however, the single body I moved HAD moved within the component itself. While the component obviously changed, the relastionship between the two components had NOT!

 

Note of interest: I notice that when you move a component, the move doesn't appear on my timeline? Could this be a symptom of the problem?

 

And, before someone asks, yes - I did export both components each time. I only included one version of the back peice here to save space. IT never changed or moved.

 

If you build the parts/assemblies/etc perfectly the first time, you will never see this problem. But I admit to being far from perfect and would expect the output to follow my iterations. If I have just done something stupid (quite possible) please let me know!

 

I have tried being very thorough and would definitely appreciate any insight.

 

Thank you

 

 

Message 15 of 20
deyop
in reply to: lkeppner

Thanks for providing the testing files.  Give me a bit and I will fill you in on what we found.

Message 16 of 20
lkeppner
in reply to: deyop

I was just checking in to see if you were able to reproduce my problem with the test files I provided. Any insights would be appreciated.

 

Thanks.

Message 17 of 20
jakefowler
in reply to: lkeppner

Hi,

 

Apologies for the delay in getting back; I think we've figured out what might be going on here.

 

When you save an individual component as an STL, it will position the STL data with respect to the origin of that component (not with respect to the 'world space' origin). And if you move a component, the component's origin will move along with it; so saving an individual component as STL will give you the same STL data no matter where that component sits in world space. I think this might be why you're not seeing object shifts reflected when you Save as STL.

 

 

0.png

 

Position changes will only be registered when the object changes position with respect to the origin of the component you choose for Save as STL (which is why the individual body move test might have worked for you: that body had moved with respect to the component's origin).

 

So, in order to get the position change registered in the STL, the objects need to move with respect to the component you are exporting. A couple of ways that might work for you:


1. If you're OK with exporting both components together in the STL, perform the Save as STL on the top level node in the browser (in the file you sent, right-click "Named Trials-V6", and choose Save as STL from here).

1.png


2. Copy the components you're moving into higher-level components, which you keep fixed in position, and then move the lower-level components within these higher-level ones. When you want to save one of these as STL, use Save as STL from the higher-level component.

2.png

 

Would it be possible to try one of these and see if this gives you the result you are after? If not, please do let us know.

 

Many thanks!
Jake



Jake Fowler
Principal Experience Designer
Fusion 360
Autodesk

Message 18 of 20
lkeppner
in reply to: jakefowler

First of all, thank you for the response.

 

The first approach (output ALL bodies as a single STL) is unacceptable because it defeats the purpose. The purpose is to have two distinctly defined STL files that can be assigned separate extruders/properites in a slicing program for additive manufacturing. Exporting as a single STL makes this impossible. And I can't export as "separate STL's per body" because, as illustrated in the example I sent, I have multiple bodies (i.e. each letter) which need to be seen as a single entitiy.

 

The second approach worked. Once I created a high level component and moved my existing component under the higher level component I was able to create an STL which "moved" relative to the higher level component. Based on your comments and my tests I think I understand that by creating the higher level component, I am "fixing" the real world origin of the high level component and any moves are now relative to THAT point in space. If that is true, then this means that a new component inherits the real world origin... And, when you move any sub-body or sub-component, they move relative to the higher level component origin and you obviously save that position information.

 

So, the question I have is then why, in the original case of a single component, do you not adjust the origin against the "real world" 0,0,0 when moved? Would this not translate into the same offset in the STL as this new approach? It seems to me that the approach you're suggesting is a work around to acheive something that should happen anyway? I am delighted having an approach of any kind that works, so thank you. I am trying to understand whether something is missing in my understanding of the underlying logic, or whether this is something that will be addressed in a later update.

Message 19 of 20
jakefowler
in reply to: lkeppner

Hi,

 

Thanks for your reply; I don’t think I fully had my head around the workflow before, but I think I appreciate the problem now. This is actually working as per the underlying logic; but you’re right that it doesn’t fit this use case very well, and perhaps we can make changes to better support this workflow in future.

 

When you export a copy of a component (either with Save Copy As or Save as STL), it is exporting the geometry contained within that component relative to its own coordinate space. This makes sense in the context that components are used to represent parts & subassemblies of the model. If you create a cylindrical part within a component, you’d likely want it centred on it’s local coordinate space. And if you exported that part for use in another design, you’d probably want the cylinder’s position to be maintained w.r.t. it’s own local coordinate space, rather than w.r.t. the world space of the original assembly from which it came from. So exporting a component is designed to use its local coordinate space as the origin. The workaround suggestions I gave are just making sure that the local coordinate space of the component you export is equal to world space, so that alignment is guaranteed.

 

But it’s true that this paradigm doesn’t fit this dual extruder workflow, where you want two components  (not necessarily with aligned coordinate spaces) to be exported separately but in alignment with each other. So perhaps we can make some changes to the Save as STL workflow to better support this. We are, in fact, looking right now at improving Fusion 360’s support for 3D print preparation, and I’ll be sure that this dual-extruder workflow is taken into consideration in the plans.

 

Sorry that this requires a bit of a workaround for now; and let me know if you had any other concerns.

 

Many thanks indeed for raising this one,

Jake



Jake Fowler
Principal Experience Designer
Fusion 360
Autodesk

Message 20 of 20
surfer2014
in reply to: jakefowler

Not sure if things have come along since this old thread ... ?

 

But I just did a test using Repetier Host on Ubuntu, and if I export via Meshmixer (running on a VirtualBox Win7-64 system), separate shells, and then add the separate files, they reposition themselves and lose alignment.

 

BUT if I drag them into the same group, they realign themselves using a common origin, and still each body can be assigned to its own extruder.

 

I tried without using Meshmixer, and it then creates one object in Repetier host which cannot be split. 

 

BTW the combined.atl file created by Meshmixer is not useful, in that it also is a single object that cannot be split in Repetier.

 

Hope that's useful to someone...

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