Weird pathing for hexagonal surface / printing issue?  

RE: Weird pathing for hexagonal surface / printing issue?

It's hard to tell from the picture, but looking at the corners, it looks like your Live-Z setting is too low (too negative). The nozzle is low enough to gouge the top surfaces. This can easily result in a build-up of filament on the nozzle, which can easily snag previously printed layers and create the mess you're seeing. The same can happen if Live-Z is too high (not negative enough) as filament doesn't adhere to the bed, curls up, and sticks to the nozzle or hotend. PETG is particularly tricky as it tends to want to stick to whatever's hottest nearby, which can be the nozzle if bed adhesion isn't good. You're after that "Goldilocks zone" where the nozzle is low enough to adhere well, but not drag the nozzle. PETG tends to like less "squish" than PLA.

RE: Weird pathing for hexagonal surface / printing issue?

So from the bottom right to the top left is the direction it printed, and I noticed that it looked like it was sticking quite easily so I moved it less and less negative as the print went on (0.1 increments) and noticed it was as less desirable texture, but still sticking to the bed. 

After it finished printing this is the view from peeling it up, and all layers essentially separated themselves upon lifting. 

When I was setting up the textured sheet I noticed that if it wasn't more negative it got less of the textured effect on the bottom.

RE: Weird pathing for hexagonal surface / printing issue?

So I'm trying to print this now, a small little thing that I'll actually use, rather than the whole Raspberry Pi case that takes a minute to fail. https://www.prusaprinters.org/prints/2016-prusa-i3-mk-filament-guide-clipon

Starting with where I left the grid it was a complete failure, -0.8

So I decreased the Z-Height to -0.9

And then -1

And it feels like it's trending in the right direction. However, this is further than was required in the square so I'm not sure if I'm doing something wrong there or not understanding what you mean by having it at the "just starting to stick" point.

RE: Weird pathing for hexagonal surface / printing issue?

Argh. I hate trying to interpret pics. It looked rough in the 1st, but if the square is falling apart, you are definitely too high. Being high at the start is actually good. Bring it down 0.08mm and work down in 0.02mm increments until the surface starts to even out. When you've got it right, the square should peel up and not pull apart easily. I've got some illustrated notes on using Live-Z herethat might be helpful.

RE: Weird pathing for hexagonal surface / printing issue?

So you think I should be lower than I was when I started out? Sorry about taking a while to respond, I'm responding pretty quickly but it appears I got flagged for moderation since I have a new account.

RE: Weird pathing for hexagonal surface / printing issue?

I may have misread your 1st picture. Print the 75x75mm square and take a pic and post that. Try to get a clear enough pic to show the extrusions clearly.

• If the angled lines have gaps between them and there are gaps between the angled extrusions and perimeters, you're a bit high. Move down (make more negative) your Live-Z by 0.04-0.06mm gaps until they start closing up, then lower by 0.02mm until it looks even.
• If the angled lines are rough, the nozzle is probably dragging. Raise your Live-Z (make less negative) by 0.06mm and increase by 0.02mm until it smooths out.

You're better off starting a bit high (the gaps are easy to spot) and move down as the gaps are easy to spot.

If you have no luck, take your PEI sheet to the kitchen sink and use some Dawn dish soap (or equivalent) on it. Nothing with hand softeners. Scrub it with a plain paper towel under hot water, rinse it, and dry it with another plain paper towel. Dry it but do not touch the print area. Don't do anything else and try Live-Z adjustment again.

If you are printing PLA, use the SMOOTH PEI sheet. If printing PETG, use the textured PEI sheet. Be aware that each has very different Live-Z requirements due to varying thickness.

RE: Weird pathing for hexagonal surface / printing issue?

I read through your site and I really appreciate it, seems real clear and I think I'm moving in the right direction. Here's the Z-Height that I had in my original post, which is what I'd set using the original method -1.350, for the entire thing.

Some slight gaps in the top left there. 

I do tend to prefer the textured sheet and have been using it for PETG, but my original post I was just trying a bunch of different things to try to get it to work. I haven't scrubbed it with Dawn though, is that potentially enough to cause what I was seeing with the original hexagonal shapes? 

RE: Weird pathing for hexagonal surface / printing issue?

Posted by: @rrobe53

I read through your site and I really appreciate it, seems real clear and I think I'm moving in the right direction. Here's the Z-Height that I had in my original post, which is what I'd set using the original method -1.350, for the entire thing.

Those pics look very close. You can try going a bit lower to see if the little dots along the edges close up. When you peel it off, it should be a solid sheet.

I do tend to prefer the textured sheet and have been using it for PETG, but my original post I was just trying a bunch of different things to try to get it to work. I haven't scrubbed it with Dawn though, is that potentially enough to cause what I was seeing with the original hexagonal shapes? 

Possibly. If your bed adhesion isn't good, parts tend to lift easily which can cause the nozzle to snag.

Mastering the PEI takes a bit, but it's worth it not to have to use goop on your bed, brims, or (shudder) rafts.

RE: Weird pathing for hexagonal surface / printing issue?

So I dunno. I changed out for the orange filament so it was easier to see while printing the test. The square looks good to me, got rid of the circles in the corner.

Yet this is still a failure... Same Z-Axis, same temperatures and layer height as the square.

RE: Weird pathing for hexagonal surface / printing issue?

If that's PLA, try the SMOOTH PEI sheet. If it's PETG, give the textured sheet a good wash.

It is possible to get a bad textured sheet. I had one that was a complete write-off. You can print PETG just fine on the smooth PEI, but be sure to put some sort of separator agent (Windex is recommended) before printing higher temps on it. 

RE: Weird pathing for hexagonal surface / printing issue?

Aside from the initial this has all been on the textured sheet and has all been PETG. I've been experimenting more, setting my bed to a lower temperature, which seems counterintuitive but seems to be having positive effects.

RE: Weird pathing for hexagonal surface / printing issue?

Posted by: @rrobe53

Aside from the initial this has all been on the textured sheet and has all been PETG. I've been experimenting more, setting my bed to a lower temperature, which seems counterintuitive but seems to be having positive effects.

I'd normally print a test layer out of solidarity, but unfortunately, my Mk3 is out of action awaiting parts. I did have a bad experience with a textured sheet, so would try PETG on the smooth PEI (with a spritz of Windex) to test. Other than that, it sounds like you're making progress. PETG should stick firmly for your 1st layer just like PLA, so the same basic procedures apply. Good luck with it!