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By Elise Moss, May 7, 2013
I have a lovely Dimensions 3D printer at my lab at Laney College. It can print an object up to 8 inches by 8 inches by 8 inches, so fairly good size parts. I have had students print everything from jewelry to fan blades (to replace broken blades on a motor) to bicycle parts.
I am the gatekeeper for the printer. Students have to submit their designs to me and then I prep them for printing.
Due to all the news and media stories about 3D printing, including a mention by President Obama in a recent speech, it seems like everyone's imagination has been captured by 3D printing. So, I would like to explain a few things.
Just because you can print something doesn't mean you should. First off, a 3D printer uses material, just like a standard printer uses paper and toner. You wouldn't dream of printing out a ream of paper filled with nonsense, so don't even think about printing out random plastic parts if you don't have a use for them.
Secondly, depending on a printer, there are some limits. Size, of course, but that is not necessarily a barrier. You can break down a large part into smaller pieces, print the small pieces, and then glue them together to build your larger part. Text and texture doesn't always come out looking crisp or clean, more like smudged. Use a clean blocky font, if you can. The more detail and the smaller details just don't look that great. I don't like parts with a lot of holes and openings, because the printer will use supporting material in those areas and it is a pain to clean out that material.
Thirdly, you can add to a 3D printed part afterwards. A lot of people don't consider that. I have advised students on how to install a threaded insert to get a tapped hole in a printed part, using sand paper to add some texture, painting the part using model paint to provide color, etc. With a little forethought, you can create something that is functional and nice-looking as well.
I get a lot of garbage files. This isn't just because I am getting files from students. If the part has been created using surfaces, it can't be used for 3D printing. The part has to be defined using solid bodies. There should be no gaps or errors. Ideally, there should be a flat face or a way of orienting the part so it can be built on the supporting platform used by the printer.
My parts are designed using SolidWorks. The students email me a SolidWorks part. I open it up in SolidWorks and do a preliminary inspection. I am looking for gaps, errors, sharp corners, too much detail or even too little detail. The part is then saved to an stl file. Next, I bring up the Dimensions software and import the stl file. I orient the part so that the most logical side can be used for the support side (the side resting on the plate). I make sure the part is scaled correctly. I try to place as many parts as I can on a plate, so I usually print multiple parts at the same time to save time and it also conserves materials.
It takes a long time to print a part. The longest time for most of my parts is in the 14 hour range. Luckily, you don't have to hang around and watch the part print. You can leave and come back. But, if you are in a rush for a part because you need to show it at a trade show or for a design review meeting, take the amount of print time into consideration and even assume you may have to print it out twice.
Parts should be printed for three reasons:
If your part doesn't meet one of those criteria, don't print it. Don't print just for the novelty of the experience. Some people are surprised that printed parts can actually be used, but they work very well. I have printed up replacement knobs and dials to be used on washing machines and dryers and they work just fine.
Like any new technology, users will try to push the boundaries of what a 3D printer can do and the technology will push back. If you want to try 3D printing without spending a great deal of money, check out your local community college to see if they have a printer available or there may be a local Tech Shop where you can rent time on the printer.
Steve Zettler, one of my students at Laney College created this plastic robot using SolidWorks and then we printed it out on the Dimensions printer.
This is an assembly made up of six parts - the arms, legs, torso and head. I was able to get five of the parts done in a single batch print, but the torso had to be printed separately because I couldn't get all six parts to fit on the tray
|Elise Moss has been teaching Autodesk and SolidWorks software for the past decade. She is an Autodesk Certified Instructor and teaches at an Autodesk Authorized Training Center in San Francisco. She speaks regularly at SolidWorks World and leads the Oakland SolidWorks user group. Elise has a mechanical engineering degree. More...|
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