Troubleshooting Supports After a Failed Mini Print
As I've been printing more and more minis, I've become more and more familiar with supports. My favorite supports are Meshmixer tree supports, mainly because I can customize them to ensure that my mini is supported in the areas where it's needed, and only in those areas. But, what do I do when I get a print that fails? Well, first I look at it!
I've been printing out Living Bones models for Gloomhaven recently and, after making some recent adjustments to the model, I had to recreate my tree supports to print the latest version. As you can see in the above photo, I wasn't 100% successful... but since the failure in that print was so focused, it makes a great example for talking about how I diagnose failed supports!
The biggest failure on that print was the sword. As you can see, there's some spaghetti in there where the tip of the sword should be, almost all the way up to the crossguard. Some of the blade actually did get printed successfully, but that's only because it's laying on that support tree behind it that goes to the loincloth, and you can see the loose garbage that eventually built up enough to get back to successful printing. So, why did the sword tip fail?
I failed to create strong supports for the tip of the blade. You can see that there are 2 support trees that were designed to support the blade during the print. It's difficult to see in the picture, but the tip of the sword did print successfully, but was knocked loose and is laying down on the brim under the spaghetti.
In hindsight, I'm not at all surprised that it failed right there. Half of the blade of the sword needed to be supported by that single support tree with its single .25 mm interface. That's a lot of plastic, building up at a precarious angle, with very little support. If you'll forgive the terrible drawing, this is what I had done with the sword tip:
One support, right near the tip, with a whole lot of blade coming off of it. During the printing process, the nozzle is going to push out some hot plastic, creating a slight downward force. See what I've done here? As Archimedes said, "give me a lever long enough... ...and I shall move the world." I've created a big lever right there and, as the print progresses, it gets longer and longer. In this case, all of that downward force eventually became too much for my one little support to bear, and so it snapped off.
So, what happens when a support fails like this? Obviously, the sword stopped printing successfully, but that doesn't mean it stopped printing. The printer has no idea that the support has failed, so it keeps going through the motions and extruding plastic. If you're lucky, that plastic comes off the nozzle and you just get a pile of spaghetti where the failed bit of the print was. More realistically, that spaghetti is going to get dragged all throughout your print, sticking to whatever bit of the print comes next after the failed part. If you're unlucky, that spaghetti will bunch up into a little wrecking ball and will knock the rest of your print off the bed.
When you're diagnosing a failed part like this, don't freak out too much about spaghetti all throughout your print. Look for the parts of the model that actually failed and resolve those parts, since they're almost certainly the source of that big swath of spaghetti. Once they're resolved, all of that loose plastic should be resolved too (or at least, only after resolving them does it make sense to troubleshoot other sources of spaghetti). I've seen prints where it looked like almost the entire thing had failed, but the actual failure was a single support tree, which in turn ruined the rest of the print.
So, how do you fix a situation like this? Do you go back and remake the model so that it'll print more easily? Well, you could, but sometimes you want a model with a shape like that and so it's nice to know how to get it to print. And, ultimately, the solution isn't all that bad. I've got a fever, and the only prescription is more supports!
I just clicked on the tip of the blade a bunch of times, allowing Meshmixer to generate a whole bunch of additional supports for that area. Each one of those supports is an additional .25 mm interface, but importantly, they are also spread out from each other. That spread limits the damaging potential from the lever effect. With better supports in place, here's the end result:
After a bit of judicious clipping with my flush cut wire cutters and some delicate cutting with an x-acto knife, the supports came free and I had a great print of my Living Bones to bring out to the table this weekend!
Update: I recently wrote a whole post about How I Make Meshmixer Supports, which you may want to check out!
The biggest failure on that print was the sword. As you can see, there's some spaghetti in there where the tip of the sword should be, almost all the way up to the crossguard. Some of the blade actually did get printed successfully, but that's only because it's laying on that support tree behind it that goes to the loincloth, and you can see the loose garbage that eventually built up enough to get back to successful printing. So, why did the sword tip fail?
I failed to create strong supports for the tip of the blade. You can see that there are 2 support trees that were designed to support the blade during the print. It's difficult to see in the picture, but the tip of the sword did print successfully, but was knocked loose and is laying down on the brim under the spaghetti.
In hindsight, I'm not at all surprised that it failed right there. Half of the blade of the sword needed to be supported by that single support tree with its single .25 mm interface. That's a lot of plastic, building up at a precarious angle, with very little support. If you'll forgive the terrible drawing, this is what I had done with the sword tip:
So, what happens when a support fails like this? Obviously, the sword stopped printing successfully, but that doesn't mean it stopped printing. The printer has no idea that the support has failed, so it keeps going through the motions and extruding plastic. If you're lucky, that plastic comes off the nozzle and you just get a pile of spaghetti where the failed bit of the print was. More realistically, that spaghetti is going to get dragged all throughout your print, sticking to whatever bit of the print comes next after the failed part. If you're unlucky, that spaghetti will bunch up into a little wrecking ball and will knock the rest of your print off the bed.
When you're diagnosing a failed part like this, don't freak out too much about spaghetti all throughout your print. Look for the parts of the model that actually failed and resolve those parts, since they're almost certainly the source of that big swath of spaghetti. Once they're resolved, all of that loose plastic should be resolved too (or at least, only after resolving them does it make sense to troubleshoot other sources of spaghetti). I've seen prints where it looked like almost the entire thing had failed, but the actual failure was a single support tree, which in turn ruined the rest of the print.
So, how do you fix a situation like this? Do you go back and remake the model so that it'll print more easily? Well, you could, but sometimes you want a model with a shape like that and so it's nice to know how to get it to print. And, ultimately, the solution isn't all that bad. I've got a fever, and the only prescription is more supports!
Update: I recently wrote a whole post about How I Make Meshmixer Supports, which you may want to check out!
How do you get the supports to show up in different colors from the model?
ReplyDeleteI'm sorry, but I think it's just always done that for me when I generate supports, so I'm not sure if I turned on some setting when I was first playing around with the software or what.
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