Skin thickness, loops and extrusion width question

[jomo]

I am trying to understand how these setting should be adjusted  and I am not getting what I expected.

I sliced a 20 mm cube with vase infill 

My settings are

Skin Thickness = .1

Number of loops = 3

Extrusion width = .64

My actual wall size was 2.15mm

I was expecting that  total wall thickness would be limited to .1 mm made up of 3   really thin layers ( yeah ridiculously  thin) loops

The number is much closer to  3 times the extrusion width with no impact from the Skin thickness setting.

The other thing is, I set the Extrusion width to the diameter of the extruded filament in air giving me .64   That seems to be way to big for a .4 nozzle. 

Any thoughts or comments appreciated.

[Steven]

Skin thickness is the thickness of the horizontal surfaces (top and bottom).

Number of loops sets the wall thickness.

Resulting wall thickness should be number of loops X extrusion width, minus "inset surface" and any overlap between loops.

The extrusion width should be set to nozzle width.  You also need to calibrate your material and machine to kisslicer (thin wall calibration).

Attached is a copy written by a user PenskeGuy.  Take a look at it and let us know if you have any questions.

[auctio...@gmail.com]

FYI,,, Your Extrusion Width DOES NOT have to equal your nozzle size, depending on the size and geometry printed this could be a detriment to your quality, and precision of printed output.

Extrusion Width equaling Nozzle Dia. produces a very low quality coarse/low res print, and is only a starting point, adjust as level of precision/detail and quality of printed part desired dictate. Finer Extrusion Width is needed to produce precise and high quality parts, small details and small parts.  Any retained filament optical properties, that you want to retain, such as translucency or transparency (e.g. T-Glase etc.), those properties in the printed output are great influenced by the Extrusion Width, Infill Extrusion Width and Width over Thickness Ratio.

Extrusion Width - ExtW

Infill Extrusion Width - IExtW

Width over Thickness Ratio - WoTR

KISSlicer used with a .35 HE Nozzle seems to like Width over Thickness Ratio WoTr to be around 1.6-2.2 WoTr or higher.

And does not like WoTR much below 1.4. (unlike Skeinforge).

Using a .35 nozzle...

For Layer Height 0.1mm :

ExtW Range :  0.12mm - 0.32mm (1.2 - 3.2 WoTr)

Preferred Default ExtW :  0.18mm (1.8 WoTr)

For Layer Height 0.2mm :

ExtW Range :  0.26mm - 0.36mm (1.3 - 1.8 WoTr)

Preferred Default ExtW :  0.26mm (1.3 WoTr)

Be careful who you take advice from, as you don't want to be mislead or chase your tail around.

Shawn

25+ Years Experience as a Manufacturing Engineer and New Product Developer

Three Years Experience... Printing 14-16 hours a day, 6 days a week, complex and close tolerance functional engineering prototypes.

Printing PLA @0.1mm Layer Height with +- 0.05mm tolerance for all dimensional shapes (except slightly undersized hole I.D.s).

No printing of... toys, trinkets, low quality prints, or other useless printed objects

[Steven]

I had intended to say something like "START WITH extrusion width set to nozzle width" or "use as starting point".  I guess the morning coffee had worn off and it was not quite time for lunch.  Right after I posted I thought about it for a second and figured someone else would offer more explanation.  Wow!

I was really hoping someone would add more detail about the relationship between the skin thickness and number of loops.  I seem to recall that kisslicer has a certain behavior if the resulting wall thickness does not equal the skin thickness.  I intentionally did not mention it because obviously don't remember it accurately (I simply don't run into it with my trinkets).

What is an HE nozzle?  Do the ratios above apply to all machines and nozzle sizes?

Shawn,

     Isn't that just a teensy bit over the top for missing the words "start with"?

[garr...@gmail.com]

I'm new to KS. I use the yellow pop-ups. When mousing over the Skin Thickness the message reads "Will make the solid skin of the model this thick (all surfaces: top, sides, bottom)" This confused the heck out of me because I thought for sure "side" thickness would be set by the number of loops x the extrusion width. Now I know that is how the side thickness is indeed set.

[jomo]

Steven    - Thanks for the info   I had a fundamental misconception about Skin Thickness. I  thought I had read that Kisslicer adjusts width parameters to give you a complete "skin" around all sides equal to the skin thickness setting it even says so in the mouse over. Now I understand that it is only top and bottom. I will try the guide you provided to see where that gets me.  

Auctio  -  It sounds like you believe the Width over Thickness Ratio - WoTR is important for fine tuning quality.  You found a range of ratios that you like (probably thru a lot of melted plastic).  So you must change Layer AND Extrusion Width  each time you want to do something different.   I will continue to ponder this when I get to the fine tuning stage but  first I want to get a wall thickness what I tell it.  Thanks

 

Garr - It seem like the mouse over info is wrong  or we are under a fundamental misconception, 

[auctio...@gmail.com]

Hello Steven,

Yah, I too know about the coffee thing...

And yes, the previous post mentioned settings are not specific to any slicer, printer or nozzle size.  

ExtW, WoTr, #Loops, and Skin Thickness settings, apply more to your design intent, part geometry, and end-use application for the part.

All are critical to your design intent, printed part's quality, level of detail realized, overall strength, and in accordance to part's intended end-usage.

Note :  HE Nozzle = Hot End Nozzle

_______________

Hello Jomo,

For me, I set my Extrusion Width, Skin Thickness, and the number of Loops to be based on several things :

1)   Respecting the printed part's structural integrity.

2)  Overall required level of detail in printed parts geometry, and intended end-usage.

3)  The perimeter strength desired.

4)  Any Wall Thickness that may not have room for proper infill, with set ExtW, IExtW, #Loops, and Skin Thickness.  Inappropriate settings can instantly compromise the infill paths and quality of infill, or negate infill completely.

5)  And if any post-process cleanup is needed, and I need additional perimeter material available for this.

Basically if you need to manually clean/file/sand/polish up the perimeters of the print, you want enough Loop/Skin perimeter material thickness as so you do not break through the perimeter Loops/Skin and penetrate the infill zone during post-process cleanup.

Quick Notes :  

• Select an Extrusion Width that in respect for the parts geometry, part size, level of detail, any wall thickness, and the printed output precision required.  A narrower ExtW/smaller WoTr which allows for superior fine details and precision in your printed parts.  This is necessary for producing clean hi-res prints with fine details, sharp corners etc.
• Select and Add more Loops, and more Skin Thickness for strength as needed.

For most printed parts, my preferred perimeter wall thickness for printing is :

2-3 Loops, .5mm Skin Thickness with a ExtW of 1.3-1.8 WoTr.

______________

Hope this helps you... Enjoy Happy Printing !

Shawn

25+ Years Experience as a Manufacturing Engineer and New Product Developer

Three Years Experience... Printing 14-16 hours a day, 6 days a week, complex and close tolerance functional engineering prototypes.

Printing PLA @0.1mm Layer Height with +- 0.05mm tolerance for all dimensional shapes (except slightly undersized hole I.D.s).

No printing of... toys, trinkets, low quality prints, or other useless printed objects.

[jomo]

 Shawn,

Thanks for taking the time to explain.  So, from my original post settings; 

Skin Thickness = .1

Number of loops = 3

Extrusion width = .64

I have a Width over Thickness Ratio of  6.4  and should be shooting for something like 1.5  -hadn't considered that would effect quality.  I will make some changes. Perhaps this  affects the actual extrusion width does not match the setting.

regards

Joe

[auctio...@gmail.com]

Hello Joe,

Yes, your WoTr of 6.4 was insanely high and would just produce crappy prints (if it prints at all).

Shooting for something like 1.5 WoTr is fine/perfect for normal printing, your results will instantly dramatically improve.

So for example :

Your LH is .1mm x 1.5 WoTr; set ExtW & IExtW to .15mm

* Best practice to set both the ExtW and the Infill ExtW the same.  Only upon very rare occasions do I ever set IExtW to a different or unequal value.  Printing with Taulman T-Glase is one of those rare occasions, depending on the part geometry and the desire to retain it's transparent optical properties.

______________

Enjoy Happy Printing !

Shawn

25+ Years Experience as a Manufacturing Engineer and New Product Developer

Three Years Experience... Printing 14-16 hours a day, 6 days a week, complex and close tolerance functional engineering prototypes.

Printing PLA @0.1mm Layer Height with +- 0.05mm tolerance for all dimensional shapes (except slightly undersized hole I.D.s).

No printing of... toys, trinkets, low quality prints, or other useless printed objects.

[garr...@gmail.com]

Hi. I just got a spool of T-Glase today and am eager to test it. To retain the transparency do you set the Infill ExtW wider than the ExtW so as to maximize the amount of plastic and reduce the amount of air space in the part? Also can I print PLA and T-Glass with the same J-Head? Or will that muck it up? Thanks. Garry

[PenskeGuy]

Skin Thickness on the sides is a minimum value. You can have 1 Loop @ 0.5mm ExtW and a Skin thickness of 2mm. The difference will be made up with Infill. If the number of Loops x ExtW exceeds the Skin Thickness value, the sides will be all Loops.