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iStill Desktop Distillery: an Exercise in Design for Additive Manufacturing

What do you get the man who has everything? The answer is obvious. Who wouldn't want their own little desktop still to help while away those idle moments?

So, why did I undertake this project? For three reasons:

The first because Lasertech, a metal additive manufacturing (AM) company in the north of Sweden, asked me to design them something that show-cased metal additive manufacturing that they could use as the ultimate executive give-away.

The second reason was to show that metal AM can be fun. Though I do love light-weight topology optimized brackets and complex fuel swirlers just as much as the next guy, it was nice to design something slightly politically incorrect just for the sheer fun of it.

And the third, and most important, reason was that I treated it as a good exercise in designing for metal additive manufacturing.

One of the largest obstacles, in my opinion, to the wide-scale adoption of metal AM is the large amount of post-processing that can be required if a part is not designed for metal AM. Some companies estimate that up to 70% of the cost of a metal AM part can be in pre and post-processing. In particular, with metal additive manufacturing support material is used to anchor the component to the build platform during printing, to help support overhanging features and, most importantly, to transfer heat away from stressed areas of the component to minimize heat distortion. This support material has to be removed, which is often a laborious manual process, and all the surfaces with which the support material makes contact need to be filed or machined smooth.

So, in a perfect world, we always want to try and design our parts to use as little support material as possible in order to avoid the labor of having to remove the supports, to produce a better surface finish, and to avoid wasting material on support material that cannot be reused.

I, therefore, treated this as a design challenge to try and design the little still to use no support material at all, other than what was required to weld it to the build plate.

In general, any overhangs with a surface area of more than a few square millimeters want to be avoided, and features with angles greater than 45 degrees from vertical should also be avoided, as they will then require support material. This angle can, of course, vary depending on the material being printed. In this project, the still was printed in aluminium so I made sure that nothing exceeded an angle of 45 degrees.

The still measures 117mm x 58mm (which is the diameter of the barrels) x 66mm high.

With this design, it meant that, after printing, the still was just cut off the build plate, shot-peened, and it was ready to start doing some heavy-duty distilling.


First published on Wohlers Talk blog at wohlersassociates.com/blog/


copyright 2017, olaf diegel