Friday, June 08, 2012

@ Alan - Rapid Prototyping Questions

Hi Alan, I was going to e-mail but I think students from the first and second years might benefit from more information about the 3D printing service that the University provides as well -

Basically, I'm interested in the requirements that the 3D model has to have before it can be converted and successfully printed, for example, when multiple components are intersected like the first image below, will the conversion process only take into account the shape that the two cubes create and ignore that there is data underneath? Or will there be some sort of error, and it is necessary to create the shape similar to the second image in order for it to work?

I'm asking this mainly because I'm currently modelling some things which I plan to get printed, but I don't know how much effort I'm wasting on making sure that every component is connected as one single mesh, rather than a base mesh with separate objects extruding from slightly under the surface of the main body of the object to give the illusion that they are physically connected, as the latter method would be a million times easier.

Secondly, what file format do the models need to be converted to, and is such a converter available to students if they want to get models printed elsewhere at a 3D printing company rather than having it done internally at the UCA?

If there's any other information that could help me or others about this, I'd appreciate it. I think in the CG Arts department there is an unfortunate lack of enthusiasm from the students about the fact that their 3D models can be printed, and I think part of the reason for this is that information about the process is quite hard to come by.



  1. Hi Simon

    To answer your questions:

    1) File formats: This depends upon the machine. It can be a .stl file (standard Stereolithography file) for viynl / plastic printers or .vrml for powder based printers (this gives you colour also).

    2) Converting Maya models to .stl and .vrml can be problematic. If the model is one piece this is obviously easier but if it is in seperate pieces its more difficult - The printer software tries to use Boolean operations to create one single mesh. A very unpredictable outcome depending upon how the objects are positioned. My advice is to try to make a single a mesh where possible and if this isn't possible use the printer software to preview the results (Booleans) and make adjustments until correct.

  2. Alright, thanks Alan,

    Is there some kind of script or plug-in for Maya that converts your model into .stl format, or is the process a little more complex than that?

    Would converting the model into .stl, and viewing the exported .stl file in any kind of CAD software be an effective preview of what the final model will look like when printed? Or would it have to be viewed in the printer software itself to get an idea of what it will look like?

    Or in other words, is there any way for someone to preview the outcome on their own machine before committing to going into the University or sending the file off somewhere?

  3. Most online 3D websites accept .obj files, i.materialise being one.

    They should be able to tell you if your model is ready for printing.

  4. Hi Simon

    Yes there is a plug-in on creative crash. If you can't find it let me know and i'll upload the version I have. Unfortunately, companies use different printing software so you have to preview in the appropriate one. Although Tom's suggestion may be a suitable for you if you don't have immediate access to a 3D printer. There is a new 3D printer in the UCA which is powder based (recent aquisition). If you see the Technicians they may still be able to print for you / help you set up the file.

  5. Okay, thanks a lot for the replies, Alan, and thanks, Tom for that link.

  6. Hi Simon,
    Maya does have an export to either STL or VRML function, it is in the plug-in menu. I can't check at the moment as I can only access the license when at Uni. I have exported stuff from Maya and opened it without any problems in the software we have at Uni for the Z-Print printer. The main condition is that the model mush be solid, no zero depth geometry, seeing some of the geometry that other students have run through the system most of the stuff we do should be fine with some minor considerations, I am yet to run something through the printer myself but the software seems pretty robust assuming you model soundly. Personally however I would go outside it you want to have really nice resolution although the prices can soon rack up, don't forget postage and packaging and if you are bringing in from outside the UK you may have to also pay import duties.