mk3 Kit scraping on infil (newb)

[ryan.r21]

Hello everyone, first time printer here and built the mk3 kit. So far I've been able to get my benchy and what nots looking really good. But I've been venturing out into some of my own designs and the have a larger foot print (~100mmx~100mm). Thats when I noticed that my nozzle has been scraping the infill. Sometimes its really bad, sometimes its noticeable if I really listen or look for it.

I've tried grid (the worst), rectilinear (little bit better than gird), and honeycomb (the best so far). Happens on both prusa freebie PLA and prusament PETG. My first lay are good enough I think that wouldn't be the issue that I can tell. My extrusion setting is "1" and on the Prusa shows "95" most of the time.

Running 3.5.1 with 7x7 firmware mod, but I only installed the 7x7 firmware to try to solve this issue.

Anyone have any ideas?

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IMG_1153.JPG (2.28 MiB) Viewed 123 times

[ryan.r21]

more photos

[robin.a]

The simple answer is to not use the grid infill. Where you get the lines crossing they double up and the nozzle can hit the bumps. Use some of the different pattern infils. I use cubic or Gyroid.

[randolph.l]

Gyroid for me. With PETG it is a requirement; for some reason PETG seems to make the problem with rectilinear even worse.

[ryan.r21]

Thanks for the suggestions. I'm kind of confused why there would even be a grid pattern allowed if it is going to scrape by its own nature. Trying Gyriod now and seams to be OK. I hear a little scrapping perhaps but nothing that will kill my print.

This makes me think that there may be a Z step miss-calibration? If the slicer thinks its printing at 1mm, and its really printing at 0.95mm, due to a each step being 5% shorter than it should be, that would could this, especially as the layers build up. How could I test for that?

I experience this in both Prusa PLA and PETG using default extrusion, temp and speed. Slowing it down doesn't help.

[rob.l6]

Gyroid for me. With PETG it is a requirement; for some reason PETG seems to make the problem with rectilinear even worse.

Funny how in the early days (like Mk2/2s days, so early firmware/slic3r) I don't ever remember having this issue, but recently (last 6 months or so) it has become a real pita with PETg.