Hi all - I’m an Industrial Arts instructor at a high school, and we bought a couple of A350’s earlier this school year. I am new to 3D printing - I’ve been a woodworker for 40 years. One of my students is interested in making a foosball table, and we thought 3D printing the players would be a good intro. He’s a Star Wars fan, so when we found a Storm Trooper model online, we downloaded it and tried to print it ( Stormtrooper Foosball Player - STLFinder ). We started it at the end of the day and when I came in the next morning, the model had fallen over and there was a big hairball of filament on the bed. For time’s sake, we sized it down to 80% and restarted it, and it fell over again at roughly the same spot just above the knees.
Luban doesn’t show that I need any supports, and the model looks pretty straightforward. I’m using the default Luban settings for PLA at High Quality. It seems very odd that the print would fail at roughly the same point on models of different sizes.
The other thing you can try is flipping the model onto its back or side, so that one of the larger surfaces is the one in contact with the build plate. From the look of the model, you probably will need supports to print in either of those orientations, so you’ll have a bit of finishing work to do, but I’d expect you have plenty of sandpaper on hand.
Also turn z-hop on if it isn’t already—that lifts the nozzle a bit when it moves without extruding filament, and reduces the chance of it smacking into the model and knocking it over, just in case that’s what’s going on.
This means a low layer height which increases the risk of some bumping and sticking to the nozzle that can pull the model from the bed.
The legs are two separate columns, so there is a good chance that where it stops/starts there is a tiny bump where it then bumps into. Especially with the low layer height.
So printing at a slightly lower quality with higher layer height is likely to help as well.
Additionally, rotate the model 90 degrees so the longest part of the “foot” is aligned with the Y-axis.
Reduce printing speed.
But as already mentioned and giving you the best chance of success: use a brim or raft. (and make sure your first layer is good and the print sheet clean so it sticks very well)
I have serious doubts about whether a 3d printed foosball player would last much more than a few good hits. Would love to be proved wrong and then I’ll print a Darth Vader goalie for my table.
A couple things to make sure it succeeds: I would suggest you switch to PETG or ASA. PLA is pretty brittle. Also make sure your infill is ~75%.
There are a few other ways to make parts stronger, but that’s a starting point.
-S
As ElloryJaye mentions, rotating that model would make it easier to print. Tall and Thin things are harder to print than short and wide. Even with zhop and brim, very narrow models can sway during Y axis movements.
Another benefit to rotating that model is strength. Because of the way a 3D printer works - depositing layers upon layer in the Z axis - objects are strongest in the X/Y axis, and weaker in the Z axis. Much like wood with a grain pattern, it’s easier to break a board with the grain than across the grain.
I suspect that model printed in that orientation will snap off the legs pretty easily. But if you printed that trooper laying on its side, the grain would be from head to toe. Which should be a much stronger grain for the use you want. You would need supports touching everywhere (or Cura’s tree supports, but that’s a different discussion), and some sand paper.
That particular model, in my opinion, would greatly benefit from an internal hole to glue a metal dowel into. Regardless, for all but the softest touches it will still break for an oblique shot.
Best chance for strength would be ABS or some of the others listed and then anneal the layers.
At that point might as well just use the 3D printer for doing green sand casting and make the models out of aluminum.
First off, thanks everyone for all of your input. And I should have given some additional detail in my initial post. When my student mentioned possibly 3D printing this piece, the first thing I told him was that PLA was not the material we’d want to use for exactly the reasons you all mentioned. My goal in printing the model was just as a “showpiece” to show off the machines and what they can do.
I restarted the print again last night, after having made a few changes. including:
Rotating the model 90 degrees on the Z-axis
Use of a raft instead of a skirt
Increased the bed temp to 73
Decreased the speed
Set the quality to Normal instead of High
When I left after school yesterday, I had very high hopes of a successful print. The print had progressed past the legs, and the torso was in the process of being printed. But those hopes got flushed when I came in this morning and saw that the model had fallen over again.
I understand the idea of printing the model laying down instead of standing up, but I don’t like the idea of having to clean up the supports afterwards. I understand they’d be needed if printed in that orientation, but I’d like to think there’s a workable way to print it standing up.
It looks a little like the raft wasn’t very solid - there was a honeycomb pattern to the raft that went into the very bottom of the model. So when I look at the bottom of the model where it broke away from the raft, I can see the same honeycomb pattern. And surprisingly, the raft popped right off the bed this morning. I was expecting to have to spend a little time separating it from the bed.
I’ll experiment a little more to see if I can find a solution. In the meantime, I’m certainly open to other suggestions. Again, this is not meant to be a “usable” piece, just a showpiece.
Once the bed has cooled, things should come off pretty easily, but when it’s still hot it should be more difficult to remove. In terms of the raft, it doesn’t need to be dense because all you need it for is to have a larger surface area on the print bed.
For some more info, did the model break from the raft when it fell, or did it fall with the raft? If it broke then that could be a reason to have a more dense raft, though it would probably indicate other issues like curling or the nozzle hitting the print at play.
It broke from the raft - the raft was still attached to the bed. I might be able to set up a video camera and let it run to find out exactly what happened. My best guess is that it was a slow, gradual fall. If you look at the photo, you can see where a group of several layers were printed off center, then it seems to have fallen over a little more and there’s another small group of layers, and then it just kept getting worse.
I tried, but can’t seem to add manual supports since there are no overhangs. But what if I imported the model into Fusion360 and added some support structure on all four sides of the feet, kind of like the supports you see on bucket lifts to keep them from falling over when the bucket is extended out … ??
The bottom is way way way too small to anchor a piece like that throughout the whole build process on a machine with these particular kinematics where the whole bed moves - it will shake itself off.
You’re going to have to use at minimum supports on the entire bottom section to give some sort of stability, and Cura tree supports that can support the middle bit would be even better. Example:
Fusion360 is a pretty poor mesh editor. If you want to edit meshes like that try Meshmixer - it will allow you to intersect basic shapes to do that, along with other model validation features. In this case though I wouldn’t bother, just use tree supports.
I’ve taken all of this input into account, and have some interestingly frustrating results. First, I found a shorter, stubbier model. Using Meshmixer, I added tree supports and successfully printed the model on one of the school printers ( although those tree supports are proving to be a real bugger to remove! ). That was Friday last week.
At home, where I also have an A350, I went back to my first model, and for the first time successfully printed it using the Normal quality settings in Luban, verifying that the nozzle and bed temps were 205 and 70 respectively, and having added Meshmixer tree supports. Patting myself on the back a little bit, I ran that same model a second time, but this time used the High quality setting in Luban, expecting “better” results. This model also successfully completed.
However, when I went back to school yesterday and compared my two “successes” with one of the “failures” from last week, I noticed something.
The purple model on the left was done on my printer at Normal quality, and the one on the right was done on my printer with High quality. While they are both unacceptably bad, the Normal quality print doesn’t look quite as bad. The print in the center is a failed Normal quality print from school ( no Meshmixer supports ), but what it printed looks really nice and is what I expected the print to look like.
I can only assume I have some kind of a calibration issue on one or both machines - at very least on mine. Someone who knows more about 3D printing than I do suggested that I have a “mechanical issue” with the school’s printer, causing the models to fall over. As for my printer, he says that my printer is “mechanically unstable somewhere”, and suggested that I do a full diagnostic on all three machines. I found the website http://www.teachingtechyt.gethub.io/calibration that walks through several calibration steps. Has anyone used this site with any success, or are there calibration steps specific to the Snapmaker line?
