Last summer I took a trip to Hong Kong. I was impressed by the large number of people using umbrellas, mostly for the sun. I decided then that an umbrella would be an excellent thing to make on a 3D printer. It has certainly taken me a while to get around to it (Valentine's Day did offer a convenient deadline), but I finally have something I'm happy with.
This is a small umbrella (or parasol) that folds, printed in place. It combines two things I enjoy: flexible structures and moving parts, with no assembly required.
With the printed canopy, this umbrella is mostly for decoration. It seems like it would be useless for rain, though it does provide some shade. However, a version without the canopy is included, so that you can attach a (more effective) paper or cloth one.
This umbrella was designed to be printed with 0.25mm layer thickness and 0.5mm line width (width/thickness = 2.0). If you want to use a different layer thickness, I recommend scaling the STL. A smaller line width is probably fine, but scaling is again recommended if you want to use a larger one. Currently it is sized to fit on a Makerbot Cupcake, but there is a little room for it to grow.
The joints have been designed to be pretty loose, but if yours end up too tight, you could try reducing the filament flow rate. If you feel like they are too loose, let me know and I can post a tighter version.
Make sure you visually preview your gcode, such as using Skeinview. You want to make sure nothing weird is going on with the canopy layer. The canopy should print as a single layer with the sections printed in continuous motions (you don't want it stopping/starting in the middle of one of the flexible sections). Luckily, Skeinforge didn't give me a problem with this, so you'll probably be fine.
Also, the canopy layer should be the second layer (layer 1, since it counts from 0). This is a little trick I discovered to make fragile things easier to remove from my print bed. Printing PLA onto acrylic, the flexible canopy sections still stick, but are much easier to remove than printing on the first layer. It is also easier to get much denser packing. However, if you don't like this trick or it doesn't work for you, you can easily slice off the first 0.25mm of the STL using something like Netfabb.
You probably want to print this raftless. For me, the biggest challenge with this print was still removing it from the print bed. If you have a heated bed that releases your print as it cools, maybe you will have an easy time. If, like me, you scrape your prints off something like acrylic, then you need to be careful and have patience. You need to free the flexible canopy and the arms before you attempt to free the center hub. Don't worry too much if you cut the canopy sections, since they can be repaired with glue afterwards, but try to avoid bending them. If the delicate strings are bent too far, it can be impossible to fix them.
I've printed this in PLA, but it might be easier in ABS, if only because it would probably be easier to repair. I've had limited success using Superglue, which seems reluctant to stick to PLA (or maybe it's just the very small surface area). If using ABS, you might try acetone.
Before trying to fold the umbrella for the first time, make sure you cut any unintentional strings and test each joint to make sure it's loose. When you pull down on the slider, notice if any of the arms is stiffer than the others and preventing movement. The umbrella won't really stay closed all the way, since the printed canopy does have some springiness in it, but that's something I hope to improve on in the future. In fact, there is nothing to keep it in any position, but to keep it up you could try a small rubber band around the shaft like on a cocktail umbrella.
I've included a stand that inserts into the bottom, it might need a little cleaning up to fit. I've also included a canopy test, because I found that the canopy by itself is a lot of fun to play with.
I have some improvements in mind, but I don't know when I'll get around to them so I wanted to post what I had so far.
Pattern for paper/cloth canopy
Something to hold position of slider
Alternate printed canopy design / denser canopy
Version with finial (separate piece)
Larger diameter version (extend arms)
Rework slider printing supports to make it look less bulky
Dimensions of STLs:
Umbrella: 89.5mm x 89.5mm x 86mm tall
Umbrella Bare: 89.5mm x 89.5mm x 86mm tall
Canopy Test: 89.5mm x 89.5mm x 5.5mm tall
Umbrella Stand: 43.9mm x 43.9mm x 13mm tall