Support structures and gaps

Still learning a lot about this but this has been bugging me for a while now so I thought I would ask.

Actually a few questions
I know this would be the absolute worst way to print this but if I wanted to print an open umbrella in its normal orientation.
Its gonna need supports!!!
1. Does the printing software determine this on its own and add it or do I have to program it.
2. how much horizontal dimension can be made with a single support.

In this image black is the project and yellow the support

3.Does the support structures tend be more like the right side or the left. The right is simply equidistant whereas the left progressively becomes closer as the verticalaspect of the specific section being supported lose some of its own vertical aspect which in itself would act like some of support.
4. How easy is it to remove. I have heard about simply breaking it off or dissolve it or cutting it what is the standard method.

I have seen projects like the planetary gears or assemblies that when printed and cleaned operate right away and are self contained with gears and everything.

Are the gaps between such items derived from the project drawing simply based on the diameter of the nozzle if it is greater parts are sperate if not they are joined.
An easy example. A bicycle sprocket and chain not only does the chain have to be separate from the gear but the chain links also have to move in relation to each other around each of the pins in the chain are all these gaps greater than the printing diameter
Here the pin of the link is in blue and the link itself is black
5.Does the gap between them have to be drawnmore than the diameter of the printing nozzle width

 

HI Jeff,
1) I believe most slicers can add supports or you can make your own. I use skeinforge, which has done a good job for me. Check out http://www.thingiverse.com/thing:11551 for a simple example of designed in supports. I printed my shell with full, skeinforge generated support because there is no flat plane at all. http://www.thingiverse.com/thing:53559.

2) You would probably not need most of those supports, only around the perimeter. You only need support when you're printing across an unsupported flat horizontal plane in space and when you're starting printing where there is not already material around it in a lower or on the same plane (like at the edges of your umbrella or if you were modeling a person with their arms out to the side a little). Even with a horizontal plane, some bridging is possible, but that really depends on the material and settings.

3) That probably depends on your slicer. I believe skeinforge uses a constant pitch and prints in a zig-zag pattern.

4) Depends on your support settings (or design), printing settings, and material. The supports on my shell were super easy to peel off by hand and a little picking with my fingernail. The supports on the ultimaker robot need to be cut.

5) Yes, you do need to design parts like that with clearance. Unfortunately, the answer isn't as simple as saying, use nozzle diameter as clearance. It really depends on your machine settings, slicer settings, and material. A good trick is to consider how stepper motors work when you design something. Since they move in steps, they can't actually draw a real circle. So, at some level, all of your holes are actually hexes that the slicer estimates. If you can tolerate it, you will get a more accurate 'hole' if you make it a hex or some other polygon.
In reality, you're usually going to get undersized holes and will need to drill or bore them to the size you want.

By the way, for about the coolest 'print in one piece' gear assembly around check out http://www.thingiverse.com/thing:53451 and my blog post about my efforts to print it at printedsolid.com. There is also some discussion in the comments of the thingiverse page about tolerances.