Episode 592 making the inner wall layer height twice as the layer height as the outer to save print time.

[J Black]

I know it has been quite a while, but has anyone tried this? I have the Prusa XL 5T and using Prusa slicer and have no clue how to go about trying this.

Thanks in advance

[3D Printing Tips and Tricks]

We did it with Simplify3D. Never tried it with any of the Slic3r branches (i.e, PS or Bambu Studio). 

[Kurt]

Hello Mr. Black,

I don't know the answer to your question, and I know some folks might get on my case for what I am about to do. But, FYI - I asked your question to CoPilot - and this was the answer:

Short answer: you can’t do that in PrusaSlicer—at least not the way the forum user is imagining.

Why it’s not possible

In PrusaSlicer, layer height is global for each layer. That means:

• Every feature printed in a given Z layer (outer wall, inner wall, infill, supports) uses the same Z step
• You can’t assign different layer heights to different perimeters on the same layer

Even when you use:

• Variable Layer Height → it still applies to the entire slice at that Z, not per feature
• Modifier meshes → these can change speeds, extrusion widths, infill, etc., but not layer height independently per wall

---

What is possible (closest alternatives) ✅ 1. “Combine infill every N layers”

This is the closest built-in optimization:

• Setting:
  Print Settings → Infill → “Combine infill every”
• Example:
  If layer height = 0.2 mm and combine = 2 → infill prints at 0.4 mm effective height

👉 Important:

• Only affects infill
• Perimeters stay at normal layer height

---

✅ 2. Increase extrusion width for inner walls

You can somewhat mimic “thicker inner walls” by:

• Increasing internal perimeter extrusion width
• Example:
  • External perimeters: 0.42 mm
  • Internal perimeters: 0.6–0.8 mm

This:

• Reduces number of passes
• Speeds up printing
• Keeps outer quality high

---

✅ 3. Reduce number of inner perimeters

Instead of 3–4 walls:

• Drop to 2 or even 1
• Combine with stronger infill

---

✅ 4. Use Arachne perimeter generator

Enable:

Print Settings → Advanced → Perimeter generator = Arachne

This:

• Dynamically varies line width
• Reduces unnecessary toolpaths
• Improves speed without losing strength

---

✅ 5. Draft profiles / thicker layer height overall

If the goal is speed:

• Increase layer height globally (e.g., 0.3 mm)
• Keep quality via:
  • Lower external perimeter speed
  • Smaller external extrusion width

---

✅ 6. Variable layer height (partial help)

This can:

• Reduce layer height only on curved/visible areas
• Use thicker layers elsewhere

BUT:

• Still affects entire layer, not just inner walls

---

Why other slicers sometimes seem to do this

You might see references to:

• Cura’s “Infill Layer Thickness”
• OrcaSlicer / Bambu Studio optimizations

These still:

• Only apply thicker layers to infill, not perimeters

---

Bottom line

❌ You cannot print inner walls at 2× layer height while keeping outer walls thinner in PrusaSlicer (or most slicers today)

✅ You can achieve similar time savings by combining:

• Infill layer combining
• Wider internal extrusion widths
• Fewer perimeters
• Arachne generator

---

If you want, I can suggest a tuned Prusa XL 5T profile specifically optimized for faster prints while keeping outer surfaces clean—that’s usually the best practical outcome for this kind of goal.

[Jody Harris]

You can do it in PrusaSlicer:

Think carefully

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[Kurt]

Wow Jody - it looks like you DID indeed "Think carefully"!

Nice job on the Pic and instructions!!!

[Jody Harris]

Actually, in my haste, I was WRONG. My proposed solution is only for infill, and was already covered in Kurt's reponse.

Sorry.

-J

Think carefully

On Thursday, May 21st, 2026 at 8:50 AM, Kurt <kurt.the...@gmail.com> wrote:

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[3D Printing Tips and Tricks]

I should point out that we did use it with S3d enough to find real disadvantages. One of the biggest was it didn’t work well for stepping along a slope… which is where the finer layers are kinda where you want them. Another was you were limited by the nozzle shape… I.e., it kinda worked for Mark 8 designed nozzles but not for the E3d styled. I’ll dig through my dB and see about repeating the episode next week where we talked about it.
As I recall… what worked best for the most use cases was to do the infill and supports at larger layer heights and outlines/shells the smaller layer heights. That gets you faster overall times yet you still get the exterior quality and it worked for all machines. I think you can do that easily in the Slic3r based apps.

Did the AI output mention any of that?

[Kurt The 3D Printer GUY!!]

Andy - you Asked if the AI mentioned ANY of that - which obviously means you Ignored the AI response. Seems you Also ignored the response from Jody - since he Stated that his suggestion with the Pic - was already mentioned in the AI response of mine!!

For instances - parts of the AI Reply:

You might see references to:

• Cura’s “Infill Layer Thickness”
• OrcaSlicer / Bambu Studio optimizations

These still:

• Only apply thicker layers to infill, not perimeters

✅ You can achieve similar time savings by combining:

• Infill layer combining
• Wider internal extrusion widths

Another AI suggestion - which I actually DID do years ago with S3D:

What is possible (closest alternatives) ✅ 1. “Combine infill every N layers”

This is the closest built-in optimization:

• Setting:
  Print Settings → Infill → “Combine infill every”
• Example:
  If layer height = 0.2 mm and combine = 2 → infill prints at 0.4 mm effective height

And - something I did for a small project - about 1.5 years ago - before leaving Cali - this is ALSO a great trick to speed things up - which Again - AI suggested:

Even when you use:

• Variable Layer Height → it still applies to the entire slice at that Z, not per feature

SO - My point being - although LOTS of people are against using AI - even for getting help like this - it turns out - the AI suggestions are indeed VIABLE and Useful!

Just sayin'...

-K

[J Black]

Thanks Kurt. I will try the a few of the things on the list. 

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[Kurt A 3d]

On a related note, the newest release of PrusaSlicer has an option to add an additional tool change every other layer.  Previously the slicer would start the next layer with the tool that the previously layer was useing.    This has now been named “Optimal” I think.  Now there is an option “Cylical” that will cause it to always use the tool heads in sequeice.   This leads to a more uniform print since when the next layer uses the same tool as the previous it will lay the new plastic down over the old plastic giving it a less uniform cooling time between layers.   

While this seems to be an XL feature, it’s probably due to the INDX.  

Kurt-A (The other non evil kurt)

[Kurt The 3D Printer GUY!!]

Why oh Why am I always portrayed as Evil???

In the 3DP world - like when you have an IDEX machine (like the Essentium units) - there is this "ABAB" vs. "ABBA" method of tool printing. What you Described sounds like the "ABBA" method. As in - 1st layer - Tool A - then Tool B - now next layer - Tool B - then Tool A! Obviously - this "ABBA" method is TRULY More efficient - since it means LESS Tool changes. What you were describing seems indeed to be the "ABBA" method. 

Now - the "Optimal" method as the Slicer calls it - really IS the Optimal method to use - what I referred to as "ABBA" - since it's LESS tool changes! 

Yes - what you state of - " Now there is an option “Cyclical” that will cause it to always use the tool heads in sequence.   This leads to a more uniform print since when the next layer uses the same tool as the previous it will lay the new plastic down over the old plastic giving it a less uniform cooling time between layers." - that is relatively TRUE. However, if you print BIG Parts - then that is not truly valid. The statement really holds more to prints with smaller parts!!!

Does this make sense to you Mr. Doppleganger ???

-K

[Kurt The 3D Printer GUY!!]

You're Quite welcome Mr. Black (yes - Mr. is an ASSumption...)...

What was NOT written previously - using BIGGER Nozzles can overall speed up print times - many times Drastically so. But, Downside - you can see the layer lines moreso...

But, if you print in ABS - you can smooth out the layer lines via Acetone Smoothing. Of course, it's all dependent upon your own project - as well as whether you potentially need things In Tolerance...

-K

[Kurt Gluck]

Kurt-1

I never said you were evil, I just I was not. However your jumping to that conclusion may indicate something… well on to the matter at hand.

I think with consumer 3d printing there are lots of smaller parts. Also as you increase the number of toolheads assuming you are using bunches of them the amount of area each toolhead is printing may go down significantly. Traditional mono color 3d enthusiasts when moving to IDX machines would for example print the supports with one toolhead and the entire model with the other. Since the about of support and the amount of model would be in mos cases significant what you are saying is true. Even when the support was relatively insignificant print/surface quality of the support is not as much of an issue compared to the object.

Now as one joins the “cult” of multi color prints, one may print finer and finer areas of the model in an alternate color, or many colors. For example I often add fine lettering in a corresponding color to toys. This lettering may be almost insignificant. In the attached picture, the dresser which is quite large at this scale (1/3), has lettering on the sides. The drawers are printed seperately. The amount of fillament used in the letters is quite small. When this dresser is printed at a Barbie scale (1/6) the letters get smaller. For a traditional dollhouse the scale would be 1/12.

Anyway that is the reason this feature is useful. Also, why it is an option and not the default.

I only have 5 toolheads the INDX on the CoreOne will have 8 and a coreone-L will have 11 I think.


Kurt-A

[Kurt The 3D Printer GUY!!]

Another GREAT Print dude - I Love it!!!

[david merten]

IMO calling yourself the nonevil one does kinda imply the other is evil...lol

Only 5 toolheads...I have 6 toolheads but, their all in their own machines....lol

I do need to get the tenlog in the garage running now its warmed up some, then I can do full FCS!

One last off topic note: 

I thought simplify3D was kaput. But I have been seeing adds on Instagram for version 5.0. Are they back, Is 5.0 a new version?

           David

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[Kurt]

David - my thoughts exactly re: Evil implications. 

As for S3D - it was something Nuts - like 5-7 years before S3D finally released a new version - which I believe is the 5.0 version that you speak of. 

But, as has been mentioned previously - folks believe it's just a little TOO late for that upgrade to finally come out - and now they are way behind other Slicer developers...

-K

[Kurt A 3d]

David

While my reference “Kurt-A (The other non evil kurt)“ could be taken as a reference to the fact that Kurt-1 has a beard and thus according to the laws of Science Fiction (  Evil-Spock  ) he must be the evil one, that is of course only if you feel that if there are two of something one must be evil.    I mean if we parse what I wrote and just substitute some other words we can see that this is not the only way to view this.

For example if you had three Kurts, lets call them Kurt-X, Kurt-Y and Kurt-Z, and lets for a moment replace the word “evil” with the word “Human” and for a moment we assume that Kurt-X is an AI-robot, Kurt-Y is a Human and Kurt-Z is a Human, then if Kurt-Z wrote “The other non AI Kurt” that would just mean that Kurt-Z was one of the two Human Kurt’s and Kurt-X or Kurt-Y but not both were AI’s.    

We could reduce this two two Kurts Kurt-Y and Kurt-Z where both were Human (though we know one like to use AI and one doesnt :-) ) and if Kurt-Z said “The other Human Kurt” that would could also be taken to imply that both Kurts were Human.

So, in this case my saying “The other non evil kurt” could just be implying that neither of us is Evil.   Of course if someone had a guilty conscience they might think that it implied that they were evil.   Perhaps it is the beard - who knows 

Kurt-A (The Kurt who doesnt like using AI, who is also non evil, though he likes pulling Kurt-1’s leg ) 

On Friday, May 22, 2026 at 1:23:30 PM UTC-4 david merten wrote: