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DeMystifying 3d- part 1

8/11/2013

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3D printing is a relatively new process for producing miniatures. In this blog, I will attempt to make clear the way that 3D printing can contribute to making miniatures, the benefits and pitfalls, and what I see as the future of 3D for our hobby.

In this post, I am going to explain what 3D is, how it works and what the limitations are.



It might look like magic, but at its heart, 3D printing is derived directly from the desktop printers found in most homes and offices in the world. When your desktop printer prints a page of text, every letter is placed by a moving print head. If you were to take a micrometer, you would find that the ink left on the page had a physical height- albeit it a very small physical height! If you were able to repeatedly run the same sheet of paper through the printer, and the printer was accurate enough to always print in the same place, eventually the layers of ink would be thick enough to feel with your fingers.

This is how 3D printing works. A 3D printer places layers and layers of material in a set pattern to create a physical object. What makes a 3D printer special is the ability to move its print head or the print bay up and down, the accuracy of the print mechanism for placing the print, and the material that you can print in. 

There are many materials and processes used in 3D printing, with new applications being found all the time. Let's look a a couple that are useable for making models...

- Acrylic resin: Probably among the most common type of 3D printing material, most materials have a resin based or plastic component. Companies such as shapeways and i.materialise advertise various types of resin based materials. The finest quality resin printing available from such services is usually called something like 'frosted ultra detail' (FUD) and is printed on an Objet or Polyjet printer in layers which are set quickly with air blowers built into the print head. This is an acrylic material which is pretty strong, although quite brittle. This will print at a resolution of 16 microns- 0.016mm layers. It is not strong enough to be moulded from, so an intermediate silicon mould will be needed to make replica pieces.  Advantages: cheaper than other processes, can get good results with planning. Disadvantages: requires support material which can leave a rough, unpleasant finish. This can make models unusable. Can be waxy and difficult to clean. Brittle.

- High temperature photopolymer plastic: A 3D printing substance used in the medical and manufacturing industry, some versions of this material can be directly placed in a high temperature rubber mould, making it great for model masters. Printed using a laser system to set liquid resin, this 'grows' the model out of a liquid bed. There are several variations of this process used for differing applications. In the right hands, it will produce lovely, smooth finishes. However, it requires a lot of expert set up to manually place support rods which then have to be removed after printing- this is time consuming and expensive. This material prints out at 25 microns, but the surface finish means it can actually hold more detail than some finer prints. Advantages: Some polymers can be placed straight in a mould, excellent finish and detail. Disadvantages: Very expensive due to labour involved, will require manual cleaning of models before casting. 

- Jeweller's Wax: Used in a mechanical printer by jewellers and lost wax casting. Designed to be melted out of a fine sand mould by hot metal, but can be used to make moulds by cold casting the masters with silicon to make replica pieces. The wax print can get very good results and the process builds a support of a different wax with a lower melt point that is then removed with a heat bath, so there is no clean up when your parts arrive. This mastering process is already used by some very successful companies and I use it myself. Unfortunately, this material is incredibly fragile and some companies have given up on it simply because they couldn't get the stuff to their moulds! Advantages: No clean-up needed- as long as you know how to make your masters. Great levels of detail.  Disadvantages: very slow print process, fragile parts are an art in themselves to work with, still quite expensive for small models, very costly for larger pieces. 

Each has its own strengths and weaknesses and at this time, there isn't a perfect solution. My preferred system is the Photopolymer plastic resins, which get the best and most workable overall results. However, with an experienced casting team, the wax process can produce excellent results a little more economically. 

In the next post, I will look at how files are produced that a 3D printer can use, the software involved in making  and checking the file, as well as common things to watch out for when working in 3D with production of miniatures in mind. 




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    Russ is the mind behind elemental miniatures. Enjoy his thoughts...

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