If I wanted to print two different infill amounts in in high stress and

3D Printing
,
1

If I wanted to print two different infill amounts in in high stress and low areas of the part would it be easiest to splice two G codes together at a layer change? Are there any other considerations I should take into effect like a solid layer between the two for increased bonding of the different infill layouts

2

Try doping the area where you need higher strength with very fine diameter holes. That will promote perimeter shells to form effectively acting as high density fills.

3

@Joseph_Chiu wow. Super cool idea. I never thought of that. Any recommendations for sizing? Otherwise I will just start playing with test prints.

4

Doping?

5

@Joe_Spanier I believe he means adding holes into the model so when it gets sliced it adds peremiters where it would have been putting standard infill.

6

Doping is a term used in the semiconductor industry to add impurities in semiconductors to add electrons or holes. I originally meant to type “spiking”, but the autocorrect on my phone put “doing”, and I realized that “doping” seemed like the better term to describe what’s being done here. (See http://en.wikipedia.org/wiki/Doping_(semiconductor) )

7

as for hole size - you’ll need to experiment. If you want “solid” areas, make the holes really small - under .1 mm diameter. If you want to have a matrix of perimeters that act like strong infills, then I’d suggest trying something approximately 3x the size of your perimeter thickness. YMMV, as different slicers (even among versions of the same slicer) can handle holes in different ways.

8

@Joseph_Chiu thanks. I will experiment over the next few days.

9

You put the holes so that they would form solid shells near the actual exteriors.

10

@Eclsnowman You know slic3r lets you adjust the infill across the Z axis on a print now? I know that’s not ideal if you don’t want a whole layer to be solid but better than nothing…
On a related note. There looks like there a lot of opportunities to develop smarter infill capabilities for slicing software, including better bonding to perimeters, etc. 2 of ideas I have that I don’t have time or code skills to realise are:
A graduated infill density from the perimeters towards the centre of the model - eg 50% infill as it touches the primeters fading to 0% at the the ‘centre’ of the model.
Saw tooth or crenelated loops (the internal perimeters) that might help alleviate warping and increase layer bonding. At the cost of print speed of course.