Stronger Spikes?

[kfsone 5]

Working on a print which includes some spike-like protrusions, after printing, these easily break off unless I spend a lot of time carefully crafting tapers at the base, and even then the top of the taper tends to act as a most-likely shearing point.

 

Further experimentation traces this down to the position of infill beneath the taper, e.g for this simple model:

 

 

With infill reduced to 10% for exaggerated effect, you can see that in the single-spike version, the infil is nicely centered under the spike, but if the spikes are nicely centered on the infil, you can see that the taper is basically an unsuspended, non-infil'd void.

 

 

I was thinking that what might help most here would be a bit of actual 3d shenaniganry, where instead of just sets of overlapping walls:

 

We could introduce a sort of z-hop tie off:

 

That is: It prints #1 and #2 as normal, it prints #3 but leaves a small gap, then it prints #4 as normal, but instead of starting #5, the 2nd-layer inner ring, it goes to the break, moves the head down half-a-layer, pushes material into the break in #3, then moves the head back to the layer 2 height. Move the head across xy to the start of the that 2nd layer middle ring, and start printing that ring.

 

leaving out everything but the inner ring of layer 1 and the middle ring of layer 2:

 

 

Although there would be no break between the link and the ring itself, the gap on the top layer here is just to distinguish the new movement.

 

Is this something that could be done generally by the slicer, or is this something that would need an addon? 

TestSpike.stl TestSpike2.stl

[kfsone 5]

I guess another alternative would be to break the purely circular path of the inner walls periodically with spars.

 

[GregValiant 1,330]

"Push material down into a cavity" I believe is a process patented by AutoDesk.

[nallath 1,124]

6 hours ago, GregValiant said:

"Push material down into a cavity" I believe is a process patented by AutoDesk.

Not entirely, but it's an area where one has to tread carefully yeah.