Dual Material STL Workflow

[altarke]

There is a great deal of talk about multi extruder setups on the forum- and it involves using STL's that represent multi materials. Now I am a decent modeler (using Rhino as well as MAX) but how do I produce a multi material STL part?
Is there anyone who done it from scratch on the forum here and can either point me into some quick tutorial or just describe the process itself?


Thanks

[Batteau62]

Bump- I don't have an answer for you, but I'm very interested to see what users respond with. The only thing I could find was this Alibre Design article: http://www.britishideas.com/2013/02/14/ ... -printing/
I am hoping for a sea change in software and file format soon. I'm not a great 3d modeler, but I understand the process. I think this goes back to stl not being a complete file format for additive manufacturing. See this pdf: http://creativemachines.cornell.edu/sit ... iller1.pdf
Chime in all you multiple extruder pioneers

[Nylocke]

From how I understand it you need to separate the parts that are different materials from each other in the model and I think they need to be different files... Not sure much past that since I think its mainly slicer specific...

[mhackney]

Ok, here is a post that will get you started.

I've attached a zip with a Rhino source file with 3 solid rods stacked on top of each other and the three individual STL files for each rod.

StackedRods.zip

(185.25 KiB) Downloaded 357 times

In Rhino, you simply create one solid for each object you want printed differently. Then you convert that solid to a mesh. In this case, I have 3 solids, 1 for each of the stacked rod sections. I then simply selected each and converted it ti a mesh. Then, you save EACH piece as an STL. You do that by selecting the mesh and choose File->Export Selected. Export to an STL file - do this for each of the 3 parts and you'll end up with 3 STL files like the ones I included in the zip file.

Now, run Slic3r. And run File->Combine multi-material STL files...

This will ask you to choose each of the these 3 files so Slic3r can combine them into an AMF file. It is a pain and not a very pretty UI but that's how it's done. Of course, if you can create an AMF from your CAD app, do that and eliminate the STL step (Rhino and most CAD apps do not support AMF yet).

Now load this AMF file into Slic3r. If you have slicer configured for multiple extruders, it will assign each part of the AMF file to one of your extruders starting with extruder #1 and working up from the bottom. Since this object has 3 parts, if you have 3 extruders it will assign like this:

bottom - ext 1
middle - ext 2
top - ext 3

If you have 2 extruders, it will work like this:

bottom - ext 1
middle - ext 2
top - ext 1

Primitive huh?

You can read all about this in the Slic3r manual here. I and others have written post processors that will take your gcode file and manipulate the extruders. So for instance, I can change the order of which extruder gets assigned to which part.

This should get you started.

[altarke]

Thanks for your example it helped clear up the process for me. I may not have multi extruder yet but I may have a reason to opt for one.

Thanks

[MSURunner]

Looks like you guys either targeted or spoke to the main principle, but just for sake of clarity, I'll toss this out there. The .stl file format was originally developed for stereo lithography printing (SLA printers), which are by nature single material machines. As such no multi-material provision was ever envisioned or needed. Therefore, as stated earlier, if you want to utilize multi-material objects, you need to either generate multiple .stl's or switch to a slicer/modeling platform that can take advantage of .amf files. Quite a few slicers are starting to take advantage of .amf, but the CAD/modelling world is being slightly slower to react.

FWIW, here's a decent article outlining the differences. http://www.develop3d.com/features/alpha ... rot-to-stl

[mhackney]

Exactly. But the issue is that AMF just hasn't taken off. There have been very few updates to the wiki and virtually no one (and no one notable) has adopted it. It's too bad since it is has a lot to offer. "Slightly slower to react" is an understatement!

[MSURunner]

I really think all it's going to take is an OpenSCAD or something of the sort to really push the big guys like Dassault and Autodesk to include AMF. If we aren't using AMF in the next two years I'd be slightly surprised...

[geneb]

Those companies are driven by customer demand, and their customers (with probably a few exceptions) don't even know what openscad is. (It's a bad programming language masquerading as a parametric design tool - and yes, I'm a CAD snob. If it doesn't support a mouse and a 3D pointing device from 3DConnexion, it's no better than a poorly sharpened crayon )

AFAIK, SolidWorks and others do support the OBJ format, which is something I thought was a multi-material object format.

g.

[MSURunner]

It's a bad programming language masquerading as a parametric design tool - and yes, I'm a CAD snob.

There is a reason why I'm not using it in my classroom But innovation (particularly CAD innovation) is rarely driven by leaders in software if history is any indication. BIM based architecture modelling was made by upstarts and then bought by the larger companies to take it where it is today.

AFAIK, SolidWorks and others do support the OBJ format, which is something I thought was a multi-material object format.

g.

Haven't sat down to look too closely at it, but I believe that .obj files require .mtl material definition files in conjunction with them, correct? Again, I haven't looked too long and hard at it, but it sounds as though .amf is much more inclusive. Also, aren't .obj files defined by planar tessellation? Probably not going to make a huge difference, but .amf should provide increased modelling accuracy with spherical tessellation.

[Batteau62]

I actually emailed Hod Lipson at Cornell. And he stated in an email back to me that he thinks widespread adoption "could" happen this year. I've sort of been following/researching this for some time. There are articles that show some movement in adoption/support. We just need that one big(US)player to stop dragging their feet
http://www.polygonica.com/blog/2014/02/ ... nica-v1.1/
http://www.3ders.org/articles/20140121- ... nting.html

[geneb]

Maybe an OBJ->AMF converter would do the job - but the slicers have to support AMF...

g.

[mhackney]

Slic3r has AMF support but, sadly, I can't find any convertors from OBJ to AMF.

[MSURunner]

Maybe an OBJ->AMF converter would do the job - but the slicers have to support AMF...

g.

Cura supports .amf

[geneb]

Right, but SolidWorks doesn't. (I don't think)...

g.

[626Pilot]

I actually emailed Hod Lipson at Cornell. And he stated in an email back to me that he thinks widespread adoption "could" happen this year. I've sort of been following/researching this for some time. There are articles that show some movement in adoption/support. We just need that one big(US)player to stop dragging their feet

Seems like some slicers can already take advantage of it. If he wants to see adoption, perhaps he can put some elbow grease into getting some free exporters written for popular CAD software. There isn't one for Sketchup that I could find. If there was I would be fine with switching to the AMF format today.

Until the toolchain is complete it may as well be the Flying Spaghetti Monster.

[Generic Default]

Nope, I just checked and SolidWorks doesn't allow saving files in AMF format, at least in the 2013 version. I don't see .OBJ in the list of formats either. Some of the larger machines that use photoresins and multiple materials have the material options built into the slicing software.

I think we need to get multiple extruders to be standard hardware or there will be no demand for the software guys to add AMF. Right now there are only a few boards and printers that support the use of more than one extruder. There are very few filament type 3d printers that use dual extruders. Support materials seems like the most important use of a second extruder to me, because it allows more complex parts to be made. After that I think multiple materials would be a huge benefit, and multiple colors would be third priority.

I really need to get both of my extruders set up and working for dual extrusion! For me the biggest benefits would be support material and different nozzles for infill and perimeters.

[626Pilot]

If we're one of the first communities out of the gate with a fully functional toolchain and hardware support for multiple extruders, we'll attract more interest from smart people who can help us figure out other things about the delta platform while they're here.

[bubbasnow]

alrighty here is a way to assign a specific extruder to a .stl inside your multi .stl file in slic3r rc3.

once you get your .stl files combined and loaded so you can visually see it in slic3r if you look at the right side there is a button that says settings, click that and go to Materials tab. here we can assign an extruder to a specific .stl which was combined.