Tips for Model Design and Ordering Prints
3D Printing is great, really, it’s fantastic and it’s nice to think you can print anything you can imagine. However, there are some limitations, and some “tricks” that make it easy to get good prints; we’ll try to cover the main points here.
Overhangs
The most common consumer-level printers work by a process known as FDM (Fusion Deposition Modelling). In simple English, this means the printer works by extruding very thin (down to 0.05mm) thick layers of plastic, one on top of the other. Imagine squeezing paste out of a toothpaste tube and moving it around to create a shape. 3DHubs has a great guide, if you’re interested. This process works well but it has one major drawback – if you try to print a model where part of the shape has nothing underneath it, for example a human figure with an arm outstretched, when the printer gets up to that point, the plastic just falls down. If there’s no other option, printers can produce what are known as “support structures”, a kind of scaffolding for the object, but sometimes a little thought in the creation and positioning of the model can avoid the need to use these. For example, could the model be printed on its back, its side, or could the overhanging part be supported by a deliberate part of the model (for example could the figure have their hand on their hip, rather than outstretched). Alternatively, could the model be printed in two or more parts which are then glued together?
Detail
Modern printers can produce fantastic detail, but there are limits. Don’t expect to print a historical soldier figure 20mm high and expect to be able to count (or even see) his uniform buttons. If your model has important detail, check with the printer first before ordering.
Colour
There are full colour 3D printers, but they’re hugely expensive (it’s hard to even find prices, they’re well into the “if you have to ask, you can’t afford it” range), so prints tend to be very expensive as well and you won’t find many (if any) small companies offering the service. So, if you want your model in glorious colour, consider that you’ll need to get it printed in a solid colour (probably white or grey) and then paint it. Or win the lottery.
Time
Most consumer level printers take time to produce quality prints (and quality is directly proportional to time). If you have a largish model and you want it at maximum quality, it’s going to take many hours to produce, possibly more than a day for very large, complex models. If you’re looking to print something like that, don’t expect to be able to get it done while you wait unless you’re very patient and have brought your sleeping bag. As always, if in doubt, ask the printer before submitting your order.
Materials
There are many different materials in 3D printing, including some exciting ones like wood and carbon fibre, but most share two common problems; hardly any are truly food safe, so while you can print your mug or egg cup in 3D, it may not be a good idea to eat or drink from it regularly, and they all melt at some point. 3D printing (for FDM) works by melting the plastic, and it remains meltable (is that a word?) after printing (which is why waste prints can be recycled) so you can’t print an oven tray or an engine exhaust manifold. Well, you can, but the first time you use it you’ll end up with a messy puddle of plastic. Some materials are more hardwearing than others, some are better at detail, some don’t like UV light (the vampire materials of 3D printing) so it’s a good idea to ask your printer what’s the best material to use for a project if you’re at all unsure. Again, 3DHubs has a great guide to material choice.