small holes in print with .8

[Outpost31d 0]

t looks like little pin pricks. I just started printing with an 0.8 nozzle I used the core settings of course, the only thing I changed was the layer height to 0.4

[gr5 2,070]

Is this spiralize mode?  aka cup/vase mode?  Just curious.  I assume not as if so it changes everything about my answer...

 

Well I recommend a shell width of 1.6mm and a line width of 0.8 so double check that.  Two passes allows for a better quality outer shell.  Also I believe there is still a bug in the default AA 0.8 profile where it enables "retract on layer change".  Make sure that is off as that could explain everything you see here.  

 

But really the most likely issue is speed - try slowing it down to 50% speed and if that fixes these "pin pricks" then slowly increase the speed (do all this in the TUNE menu while printing) until they come back so you know your top bump-free speed.  

 

 

[Outpost31d 0]

Thanks for that, the default line thickness (that is 'shell width'?) for 0.8 is 1.37 so i'll change that to 1.6.  'Retract on layer change' is off by default and I will try the tune menu. Appreciate your help!

[yellowshark 153]

@gr5 is right in everything he says but you may have misinterpreted. I do not have the latest Cura version and I think some of the wording has changed. First there is your nozzle size, then your line width and finally your wall width. In older Cura nozzle size was defined in printer settings and in addition within the main cura settings you had additionally line width and wall width. I think nozzle size and line width have now been combined, if you check the Help I suspect this will be confirmed.

 

You need to set line width to 0.8 and you are recommended to set wall width to 1.6, i.e. the wall will be made up of two passes.

 

Do not forget with a 0.8 nozzle you are extruding twice as much material as you would with a 0.4nozzle and therefor you will almost certainly need to adjust your normal settings - i.e. your print speed (slower) or your extruder temp (higher) or a combination. But I think @gr5 recommendation is wise.

 

Your overall finish is poor so you need to improve your settings; I have always found a 0.8print to be good, indeed often better although the geometry will decide for you whether it is the best choice.

 

If I can work out how to post a pic on the new forum I will post an example for you to aim for.

 

 

[cjs 34]

3 hours ago, gr5 said:

May I ask you mean by bumpouts? What the cause of such besides speed? 

 

56 minutes ago, Outpost31d said:

Thanks for that, the default line thickness (that is 'shell width'?) for 0.8 is 1.37 so i'll change that to 1.6.  'Retract on layer change' is off by default and I will try the tune menu. Appreciate your help!

I think @gr5 means wall thickness set to 1.6mm and line width set to 0.8mm. If you use those names they should be found by the search command   

[yellowshark 153]

0.4 nozzle

 

0.8 nozzle

[Outpost31d 0]

Ok sry, now I'm a bit confused, attached a screenshot, there is wall thickness and wall line count.  So my wall thickness should be changed from the default for the 0.8 core which is 1.37 to 1.6? 

 

Edited January 13, 2018 by Outpost31d

[kmanstudios 1,120]

Let me see if I can confuse you some more.....hopefully not, but.....

 

The wall thickness is a measurement so you can input an actual dimension.

 

The Wall line count is either:

 

(A) a multiple of the line width [Wall line thickness = 1.5/line width = 0.35, so rounding down to the nearest multiple, Wall line count = 3]; This is handy when you have a wall width that is important, say a divider, and the actual dimmension is more important than the wall line count.

Or

(B) a direct amount of wall lines that overrides the wall line width. This is handy when just thinking about wall lines for strength purposes as wall width may not be important.

 

Just to go one step further, you can adjust your line widths a bit to beef up the thickness of each wall or slim it down for a tad more detail. This will of course be input into the wall width/line calculations.

[gr5 2,070]

I agree: it's confusing.  "Wall" thickness used to be called "Shell" so that adds confusion.  A solid cube would have 4 sides and each side is normally printed as 1 or more walls/shells and then an infill pattern inside that.  You get better quality if you have at least two passes on these 4 walls (on our cube example).  More than 2 only increases strength, not quality.

 

Also it's best if the width of each of these (lets say two) wall passes are the same width as each other and the same width as the nozzle (or a little smaller).

 

So for a 0.4mm nozzle I usually plan 2 or 3 passes and so make the shell/wall width exactly 0.8 or 1.2mm to get exactly two or exactly 3 passes.  If you make it 0.9 or 1.3 then cura will increase the line width and overextrude and you are at risk of underextrusion issues.

 

Similarly for a 0.8mm nozzle I like 2 passes so I set the wall thickness to 1.6 (not 1.5 or 1.7 - I want these line widths to match my nozzle width for best results).

 

Cura likes to default a bit small which is fine - cura defaults a 0.4mm nozzle to having 0.35mm line widths so if you want to go with that then you could go with 0.7mm or 1.05mm wall thickness.  If you *don't* go with exact multiples then you will often get pretty ugly things happening.

 

 

[Outpost31d 0]

Ok I think i've got it, thanks for everyones help!

[geert_2 556]

On 1/12/2018 at 8:41 PM, gr5 said:

...

 

What is the technical relation between speed and this bumpiness? I guess it has to do with higher pressure in the nozzle, but I don't see how a higher pressure would cause these irregularities? I would expect them near corners, where the head has to slow down, but not halfway a smooth curve? And if they would occur, why not on every layer, but seemingly random? There must be a valid technical reason, because the facts are what they are, but I just don't see it...

 

[KristelB 5]

On 13 Jan 2018 at 11:47 PM, Outpost31d said:

Ok sry, now I'm a bit confused, attached a screenshot, there is wall thickness and wall line count.  So my wall thickness should be changed from the default for the 0.8 core which is 1.37 to 1.6? 

 

 

I see that you're changing your fast profile (with 0.2 layer height) to a 0.4 layer height. Speed settings are linked to the layer height, so this changes the settings to be not optimal anymore. Cura has a 0.4 layer height profile for 0.8 print cores. You can make them visible by assigning both extruder 1 and extruder 2 to a 0.8 print core and then select sprint (0.4 mm) in the profile options. This will result in much better print quality.