Printing With a 0.8mm Nozzle Help

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Greetings my fellow snapmakers, boy have I got an issue that I have been, as of yet, unable to solve and am looking to see if anyone has any ideas or thoughts or, dare I say, a solution.

I have changed out the hot-end with one that I installed a 0.8mm nozzle in as an attempt to print some board game player trays with PLA, at first I was having issues with the first layer missing at the very start but that seems to have gone away once I changed a few setting and used the Cura profile that was suggested to me by another user. However one problem still haunts my prints, what looks to be under-extrusion whenever a travel takes place.

This is a great example, I am seeing this section missing on the inner wall, added to attempt to hide the issue from the finished product. However that causes issues when it comes to the player trays in which the inner wall is showing as seen below;

There is some evidence that this happening with some of the infill but I am less worried about that as it will be covered by the top layer.

So far I have upped the temperature to 220C, changed the flow rate to 114%, reduced the travel speed from 100mm/s to 45mm/s, nothing in the speed is set to over 30mm/s. I have made sure that the e-steps are good and I have changed the K factor to 0.03 as it seem to run the best on the marlin test (I will say that the test did NOT like the 0.8mm nozzle as it did grind the filament at least twice and was a pain to get to stick to the bed).

I have the retraction set for 1.5 mm at a speed of 60mm/s and no extra prime amount, combing mode is off and the nozzle is set for 0.8mm in the slicer, Cura. Running a layer height of 0.24mm with a line width of 0.8mm. Shell is set to 1.2mm and 2 walls with a top and bottom thickness of 0.8 and 4 layers each

I did suspect a clog however I have run several cold pulls and have seen nothing that would indicate that this is an issue, and, if it was, it should have been solved when I completed the cold pull.

I have seen people say that a 0.8mm nozzle will not work with the stock head and others saying that they have gone to a 1.2mm and have had no issues, I am going to believe the latter as I have seen working prints.

I have run several tests and I am starting to wonder if I did something wrong on the install of the nozzle or if what I am asking the printer to do is just not something that it is capable of, if that is the case I can always go back to the 0.4mm nozzle and take the longer print times. However I am sure that there is a sweet spot that I am missing so I am looking for some advise or direction.

[clewis]

Do you have retraction enabled? I’ve had the same issue on some of my prints, particularly when I’m printing 0.4mm layers with the stock 0.4mm nozzle. A 0.8mm nozzle with a 0.2mm layer height will need to feed the same volume of filament. It was less of a problem when I print with a 0.2mm layer at 60mm/s (the Luban Fast Print setting), but still exists a bit.

For the part I was working on, stringing wasn’t an issue, so I disabled retraction. It seems like that might be the case for your print as well. If stringing would be an issue, you can try reducing the retraction. Lots of people have found the default retraction of 6.5mm to be too much, and are using values closer to 1mm.

Disabling retraction didn’t completely fix the issue for me, but it did make it a lot better. I suspect that it’s a combination of retraction and print speed. I usually only print a 0.4mm layer height when I’m prototyping, and use 0.1mm for final prints, so I haven’t really taken the time to properly solve it.

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I am considering turning the retraction off and seeing if that makes a difference. My next idea was to increase the speed of the retraction after the move, so it would be 60mm/s up and 70mm/s down.
Idea number three is to add in a small prime amount and see if I can ‘reload’ the missing section.
But I do agree, it totally seems like a retraction issue and I have been working with that theory for a while as everything else, expect wraping, seems to be totally fine.

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So I did change the speeds with no real change however I am now noticing wisps of PLA around the nozzle and fans.
I am thinking that there is some oozing coming from somewhere. So my next idea is to add some priming to the retraction settings and see how that works out, my only concern is that there will now be over-extrusion in places.
The trials continue.

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So, small update here.

I have been messing with several settings (K-factor, retraction speed, retraction off, increase flow) and have gotten some results, granted nothing so far has totally solved the problems.

Ignoring the missed lines, odds are that is due to stopping mid print or due to a wrapping issue I am working with, you can still see some infill missing and then, for some reason, starting again.

Here you can see the issue plain and simple, this is with a draft shield in place and zero retraction, and the large gap is plain to see.

I am almost at my wits end with what I can do to get this to do what I want it to, or even if it is possible. Granted I will keep on testing as there has to be some way to get a good looking player tray with a 0.8mm nozzle without large holes in the infill.

The next step I am going to have to take it to put the flow rate at the calculated number that I found while doing baseline set up when I installed the new 0.8 nozzle. After that I am not sure where to go next so, still looking for ideas.

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And now I think I have found the solution!

Cura has a setting for Outer Wall Wipe Distance that was still set for 0.4mm, I have changed that to 0.8mm and changed the Z seam to be shortest path, this seems to have either removed, in the case of the player tray interiors, or lessened greatly the issue, in the case of the outer wall.

I will be playing around with it more but that seemed to make a large difference, so much so that I turned off the second wall and things looked really good!

Will update if this does indeed keep the issues at bay.

[ctaddey]

The wipe distance has nothing to do with the nozzle size. According to this page it’s just a travel without extrusion.

Shell settings

But hey, sometimes things just unexpectedly works…

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Right? I think the extra movement is giving the printer more time to get plastic into the nozzle after a travel move, which I think was the cause of my issues.