As my first project, I'm trying to design a holder for glass vials, for a scientific application. The photo below shows the latest design iteration, and also shows the problem with it:
As you can see, one of the clips that's meant to hold the vial in place has broken off. This happened after inserting the vial once or twice.
I think I understand the reason for this. It's because I'm printing in the orientation shown below, in order to avoid the need for supports. (This will be more important later, when I scale it up to an array of many holders.) This means that it's relying on the strength in the z dimension, which is much weaker than in the other two directions, because it relies on the cohesion between the layers.
My question is whether I can do anything about this by changing the design of the clips, without abandoning my hope of support-free printing. I don't care at all what the design looks like, except that as much of the vial as possible needs to be visible from the front. I'm printing in ABS.
I have tried varying the thickness of the clips. Thinner ones don't break as easily, but they are a bit floppy and aren't very good at keeping the vial vertical. The ones shown are the thickest I've tried - I'm afraid that if they're too thick they won't bend at all. (The vial is supposed to be inserted from the front rather than the top.)
Edit just as an update, here's what it looks like using John Biddle's suggestion, which works perfectly:
Considering that you wish to print the clip in the vertical orientation but without supports, I would suggest that you create a suitable taper of the clip from the bottom. The taper would provide necessary support-free support but may reduce the amount of bottle access one has to remove it from the clips.
As such, you could also reduce the amount of the straight vertical segment of the clip at the front, which would allow the support-free support to start at a higher level from the bottom.
If the bottle bottom encirclement is raised, you'd receive additional retention. You could then reduce more the upper encirclement and taper for easier release.
I too prefer to design models that require no support, but have run into the same circumstance, where the weaker axis takes a disproportionate load.