Organic support directly on a printed base, not on print bed  

RE:

You can select "supports everywhere" in the top right below the printer selection.

And consider setting contact distance (top and bootom) to 0 (soluble) if you want the supports to be stable and not easy to remove...

RE: Organic support directly on a printed base, not on print bed

The gap between the hole and support is controlled by the support xy separation distance.  That too is configurable, so set that to 0 and the support will be allowed to touch the part.

RE: Organic support directly on a printed base, not on print bed

Thank you for the first two answers.

The support was already set to "supports everywhere". Without that setting, the letter "U" wouldn't get a support.

If I delete the holes and choose "support everywhere", the support still starts at the heat bed, but from the outside of the base plate. It seems that the slicer prefers the bed as starting layer, even if it would be easier and less material with starting at the top of the base.

Can I create an area around the base plate as a "no go area" for the support? I tried it with an additional part, and set the type to "support blocker". This has no effect.

RE: Organic support directly on a printed base, not on print bed

@popatze

You have not provided a working example of your project, So I'm guessing your using the default settings for supports?

The default settings are NOT the best settings, they are only a starting point.

To achieve organic supports that do not start on the print bed, you can use either "For support enforcers only" Or "Everywhere" each of these settings could require some changes to other support settings, depending on how your model is setup.

In this case I'm making my best guess based on the Images shown that you have not tried changing the "Maximum Branch Angle:" and that it's still set to 40 by default. If you were to make this number smaller it will decrease the allowable angle of the supports and attempt to constrain them to the top of the part you have shown. I'm going to suggest trying a setting of 30 in this case. you must keep in mind that the height of your supported parts plays a roll in this, Taller parts (parts further from the bed) require less angle to reach the bed, Slic3r prefers to put supports on the bed. Using a lesser Maximum Branch Angle: will help to constrict them to the part you are trying start them on.

As Robin mentioned

consider setting contact distance (top and bottom) to 0 (soluble) if you want the supports to be stable and not easy to remove...

I will add to this, also consider turning off "Top interface layers:"

Keep in mind as you play with the support settings and part placement, that changing one setting could effect a previously changed setting, it takes times and experience to learn and control them, rest assured once you get there it's really pretty easy to deal with.

Good luck

RE: Organic support directly on a printed base, not on print bed

Can I create an area around the base plate as a "no go area" for the support? I tried it with an additional part, and set the type to "support blocker". This has no effect.

This only really works when support placement is set to 'plate only' as it effectively blocks the bed, but doesn't always work when set to 'Everything'.

I'd try fiddling with reducing the allowed angles to effectively shrink the spawn area until it's within the dimensions of the lower part.