Nozzle scraping / bumping against infill - Problem?  

RE: Nozzle scraping / bumping against infill - Problem?

Cubic crashes into itself like grid. Pick an infill that doesn't, like gyroid, if it's causing issues or bothers you. If it's not a problem, it's not a problem.

But it shouldn't be crashing on travel moves unless your travel lift settings are wonky.

Grid is notorious for this, I presume it's preserved as it was the only fill at one time.

Gyroid is rather slow unless you need the resilience.

The various cubics shouldn't crash - are you getting some warping?

It may shake a few screws loose but the extra nozzle wear will be negligable.

Cheerio,

RE: Nozzle scraping / bumping against infill - Problem?

I had once an extreme situation when a grid infill was layered exactly in X and Y directions on the the whole bed of the Mini - this was a big flat surface few millimeters in height, which started to cool down on the corners and the edges but stayed warmer in the middle and it caused the printed part to warp in such way that the middle was going upwards.

As a result of warping when the print head started to loudly rattle over the infill in the middle. After some time I noticed that when the head was moving in Y axis it was getting noticeable force pushes, causing the X axis to twist in different direction depending on the movement - it is caused by the fact the nozzle is few centimeters away from X axis.

 When the nozzle was moved to the front of the printer bed it was moved downwards, and when it moved way to the back of the print it was getting moved upward. This resulted in different sound when printing and different wear (minimal) and thus extrusion from the nozzle. Notice that moves in X axis were also affected but they sounded differently but the strain in that axis is a bit different.

The noise was so loud that I was surprised as this was a sign there is something mechanically not right with the printer - it's just better not to have such physical strain on it, especially on the Mini because it has a more delicate parts than other models.

Since then I use rectilinear and avoid grid whatsoever. Less noise, less stress.

RE: Nozzle scraping / bumping against infill - Problem?

Posted by: @diem

Grid is notorious for this, I presume it's preserved as it was the only fill at one time.

Gyroid is rather slow unless you need the resilience.

The various cubics shouldn't crash - are you getting some warping?

It may shake a few screws loose but the extra nozzle wear will be negligable.

Cheerio,

I've often wondered where the myth that cubic doesn't bump into itself came from. All 3 orientations are laid down in each layer of infill, leading to a nozzle bump every time the infill crosses a previously laid down line in the same layer. Look at the gcode preview and scrub left and right with the in-layer progress bar if you don't believe me. Now, the bumping might not be as bad as grid because the bumps don't happen at 90°, but they do happen.

If you want to save filament by not infilling where support isn't needed (like adaptive or support cubic) but want to avoid the bumping, try lightning infill. But that one might have curling issues (I haven't used it enough to verify). But lightning does have a lot of travel moves even on a simple cube.

RE: Nozzle scraping / bumping against infill - Problem?

Just use rectalinear, it's nearly as strong, doesn't cross, doesn't have crazy print head paths and prints relatively fast.  I use it for 99% of prints. 

I've used cubic and gyroid on occasion on parts that I was really struggling with warping, or adaptive cubic when really trying to save weight.

Adding perimeters will generally add more strength than switching infills.

That's my 2¢>

RE: Nozzle scraping / bumping against infill - Problem?

+1 for rectilinear. My default infill too.

Gyroid is fine but slower and I wonder if the constant change of direction that the steppers endure with this infill will shorten their lifespan.

I've often wondered where the myth that cubic doesn't bump into itself came from.

Not quite, I wrote:

The various cubics shouldn't crash

- because the cube walls are always inclined so that as the head comes across they deflect.  Sometimes the second/third layers are a little noisy as they are constrained.

As a rough guide:

Cubic for stiffness.

Honeycomb for the rare occasions where stiffness is still desired but cubic is generating a bias - maybe a couple of times a year; it really shakes the machine.

Gyroid for resilience, 'though it's a little slow.

Cheerio,

RE: Nozzle scraping / bumping against infill - Problem?

I always consult this Prusa guide when deciding on an infill: https://help.prusa3d.com/article/infill-patterns_177130