Changing infill on specific region of a part?

[kevinz]

Hello,
I'd like to design a beam and use self-tapping screws to attach each end to another element. I'd like to increase the infill to 100% in just the screw regions, to produce a stronger mechanical joint, while at the same time, maintain 20% infill for the rest of the beam.
Here's a picture, and an attached example file, of a beam 1/4 inch square by 3 inches, with 1/2 inch long holes in each end:

Screenshot from 2019-11-14 10-10-18.png (2.62 KiB) Viewed 1054 times

Is it possible in FreeCAD to specify that the first 1/2 inch of each end of the beam should be 100% infill? If not, I'm using either slic3r or Cura (for a Lulzbot Mini2 printer) as a slicer. Can either of these create this characteristic?
Thanks for all your help and advice. As always, critizisms and suggestions are always welcome on my drawing. I'm a newbie and still on the sharp uphill portion of the learning curve.

-Kevin

[freedman]

Infill is set by the slicer but if your willing to work at it you could model it with some inner material removed. Something like start with a hollow tube, then add material where you want to get your final solid.

[chrisb]

Keep in mind to set your slicer to 100% infill, if you model the infill yourself.

[DeepSOIC]

Yes. It is done by "modifier shapes".

In FreeCAD:
model a solid that contains the piece of your part to be 100%-infilled, and export it as a separate stl.

Then, in slic3r:
1. add the part stl to the plater
2. double-click it in list, you'll see a dialog. Press Load Modifier button.
3. point it at the modifier stl.
4. select the modifier shape in the list. In the area toward the bottom, click "+" button, pick a setting (infill density, in your case), and alter its value
-> done, slice it, check it, print it.

In Cura, it should be possible too, but I don't have a how-to as I've never done it myself yet.