Print circle arcs without supports I'm still putting aside money for buying my first 3D printer and I'm designing all the things I have to print.  

As I have a lot of things to print I would like to print as much of them as possible in a single print.

I have some arcs of circle (between 90° and 320° and 10/30 cm of diameter) and I'm going to slice them so I'll be able to print many of them, vertically, in a single print. I read in the internet that I cannot print over 45°... but starting from where?

The image below shows how I would like to print my (orange) things



I suppose I can print my things without supports because from Y-start to Y-end they are &lt;= 45° (as the green line shows) is that right?

The red line, instead, shows a case where the angle, starting from a (Y: 50%) point, is higher than 45°.

So the question is: Can I print my things in such way?
This depends on your material, your nozzle diameter, and your layer height. In general, shorter layer thicknesses with wider path widths will give better overhangs. And note that the last bit of each of the larger arcs are nearly horizontal, and I do not expect them to work well without support material.

See the excellent answers at How can I improve the overhang angles my printer can successfully print?