Making Meshmixer Supports, Part 3

So, about that whole trilogy thing... well, I guess it happened after all.  If you haven't read them, I already wrote about Meshmixer support design theory in part 1, and Meshmixer support implementation tricks in part 2... so you may want to read those before diving into this post ;)

I've been working on more complex models and so I've had to learn how to make more complex supports.  I think that the sweet spot for the Post Diameter setting is 2.5 mm.  That's thick enough that it's pretty stable and is less likely to warp during the print, but is still small enough that it's not wasting a ton of filament and can fit into small spaces.  That said, I've been finding reasons to deviate from that standard lately.

Why would I use a smaller Post Diameter?  It can fit in even more places!  Minis and game pieces often have some tight spots that need support, especially a highly textured model.  Support trees with thick posts are more stable, but thinner posts can sneak into places that their thicker counterparts can't reach.  So, I use a combination of the two!  I initially generate my support using 2.5 mm posts, but then I'll reduce my Post Diameter to 1.5 or even 1.0 mm to manually connect specific parts of the model to those stable posts.  When I'm drawing thin posts, I do everything that I can to keep them as short as possible, as the longer the post, the more chance it has to flex/snap/whatever.  Fortunately, I've almost always got a nice thick post nearby that I can snap it onto.

There's actually a bit of a trick to making sure that there's a thick post nearby.  If I can't get a valid thick post near the point that needs support, I'll use shift-click to force Meshmixer to draw it, even if it intersects with the model.  This post is temporary, so it doesn't really matter that it's overlapping.  Then, I'll draw a second support post, connecting some part of that first one to the printer bed.  It's important that this second support post not intersect with the model, because it's going to stick around.  Then, I can use ctrl-click to delete the first post, leaving the second "headless" support post in place.  I can then reduce my Post Diameter size to whatever it takes to interface with my actual model and connect that thin post to my nice thick one.

Another parameter that I use in a similar fashion is the advanced setting, Tip Height (under the Advanced Support panel).  I usually keep that at 1 mm, which basically determines how quickly the tree tapers from its post diameter to its interface diameter.  The top of the tree then shrinks from 2.5 mm to .25 mm over the course of 1 mm.  If I need that tip to reach into a tight spot though, I might increase the Tip Length to 2 or even 3 mm, which gives the tree a longer, thinner tip that might allow it to connect to a busy part of the model.  Once again, I don't typically use those longer tip lengths universally, but they can be great when drawing secondary trees.  For example, when supporting a weapon, having secondary trees with longer tips can sometimes allow you to get additional support trees onto a blade that might be at an angle that prevents other trees from interfacing.  Additional supports on an angled weapon can be the difference between a successful and a failed print.

Any time a support tree is narrower, be it because the Post Diameter has been reduced or because the Tip Length has been increased, its strength is going to be reduced.  By using those finer-but-weaker posts for only very short distances, you can get their benefit while protecting yourself from failures caused by a thin support failing mid-print.  This process allows you to support otherwise unsupportable parts of a model or to add more support to a delicate piece, allowing it to print with better stability.  Either way, it's been an important set of techniquest for me to use and has helped me to get more successful prints!