Nozzle diameter vs. Layer height

In another thread I mentioned I thought the limit for my 0.4mm nozzle was 0.14mm layer height. And was quickly replied that you can go much lower even with the large nozzle.

So my questions are:
How low can you go given the diameter of your nozzle?
What speed do you have to run at?
Can you still print bridges?
Can you still print over hangs?
What width over thickness do you use? Wider than your nozzle? Narrower than your nozzle? Same?

Please provide pictures if possible.

Quote
My repstrap
0.14mm layers
0.4mm nozzle
w/t 2.85
20mm/s perimeter, 30mm/s infill
temp 180c
Poor overhang and bridging capabilities at this height.

0.14mm_snake_display_small.jpg

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Is this using SKIN on the perimeter? or is that real layer height of 0.14mm?
I was about to start some testing to figure out exactly the same thing. I'm seeing a much closer link between speed and temperature than I initially imagined would matter.

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[richrap.blogspot.com]

richrap Wrote:
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> Is this using SKIN on the perimeter? or is that
> real layer height of 0.14mm?
> I was about to start some testing to figure out
> exactly the same thing. I'm seeing a much closer
> link between speed and temperature than I
> initially imagined would matter.

Actual layer height.

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FFF Settings Calculator	Gcode post processors	Geometric Object Deposition Tool Blog
Tantillus.org	Mini Printable Lathe	How NOT to install a Pololu driver

Sublime Wrote:
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> In another thread I mentioned I thought the limit
> for my 0.4mm nozzle was 0.14mm layer height. And
> was quickly replied that you can go much lower
> even with the large nozzle.

Yup. [www.thingiverse.com] (higher res: [ultimaker.googlegroups.com]∂=4) is an example of this. Sliced with netfabb with a 0.02mm perimeter and 0.04mm infill. Yes, cheating a bit with a Skin(-like) method but still pretty darn tiny.. Stock Ultimaker with 3mm PLA and a 0.4mm nozzle.

> So my questions are:
> How low can you go given the diameter of your
> nozzle?

I think you can pretty much go as low as you'd like until you hit the mechanical limits of the bot or the limits of the material. My old Cupcake really struggled to get under 0.1mm, even when I tossed the DC extruder and replaced it with a stepper extruder - the stock 4-threaded-rods Z axis just wasn't accurate enough. ABS I found started having problems (which rapidly got worse as you went lower) with overhangs under 0.15mm - maybe an extruder-mounted fan would have helped that.. dunno - but with PLA I've printed (non-Skin) at 0.075mm without much problem..

> What speed do you have to run at?

Tricky question that I don't think anybody has really tested. In general, slower is usually easier.

There's some range of extruder speeds that your rig is most happy at. Your chances of success probably increases if you stick to the center of this range. How you determine the range and where a given print profile fits into it isn't something I've thought much about - you could just eyeball how fast your extruder turns when printing your best profile then shoot for something that looks about the same. I'm sure math could be done, too.

> Can you still print bridges?

Depends.. The way I've gone at this before is to try to keep at the thinnest thread width possible. The maximum thread width a nozzle can do is pretty obvious but I think the min thread width is less so - you can probably go thinner than you expect.

Eventually, the layer height will drop to a point where the w/t needed to keep above the min thread width increases so much that bridges get unhappy. You can probably play games with the bridge feed/flow modifiers to buy you some room here but support structures will probably be needed to do anything serious.

> Can you still print over hangs?

See Yoda you should.

> What width over thickness do you use? Wider than
> your nozzle? Narrower than your nozzle? Same?

Some experimentation to see what you can actually use for min and max thread widths would be good. From there, chose w/t as normal (within the min/max limits) based on time/strength/quality/bridges/etc needs.

The easiest thing is to work out the thread width of a profile you like, drop the layer height to where you want to be then figure the new w/t based on the thread width from the good profile..

Edited 1 time(s). Last edit at 10/07/2011 09:39AM by Dave Durant.

I have not been able to get satisfactory prints in ABS lower than .15mm.

I've done some small things in PLA with .075mm layer height and 3-4 width/thickness. I don't see the point in going that low in most cases as you can't really see much difference from below .15mm in 90% of things.

I printed them both at 25/50 mm/s

Edited 1 time(s). Last edit at 10/07/2011 10:28PM by Andrew Diehl.

Hi folks

As a relative newcomer to the 3d printing game it is very interesting reading about the skin, non skin thing.

I have found it much, much easier to print a whole object at 0.02mm, rather than having to tweak settings to allow for larger layer heights to be laid internally whilst maintaing quality.. Unfortunately for me, it's just not practical to print everything at the smaller layer height due to the much longer print times that would result.

Quality wise I see a big difference even going between the 0.04mm perimeter and 0.02mm perimeter or skin on a more shapely and detailed item (mind you they are hard to come by), which otherwise shows a heavily stepped surface. It also makes for awesome overhangs.

Sorry I'm a bit off topic, but I have only used Netfabb. I do however bow to you all in deep respect, skienforge is a foreign language to me and seems to have an impressive learning curve.

Kind regards

Paul

P.S. It is also very interesting to a new comer to see how layer heights are perceived. Maybe I should change the wall to be the single layer height and the fill to be a double layer height?

Do you really mean 0.02mm, i.e. one fifth of the thickness of paper? You would need to a microscope to tell the difference between 0.04 and 0.02.

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[www.hydraraptor.blogspot.com]

Hi nophead

I agree on a flat vertical face 0.02 mm or 20micron layers are wasted as 40 micron is almost perfect anyway. However if you want a nice smooth slope or sphere they come into there own. Minimising the stepping pyramid look and helping with overhangs.

For me the whole point of working to go from a 0.2 mm 'low quality' print and a high quality 0.02mm one, was that the first looks as if it's been made out of layers whilst the other one could be mistaken for a molded item with a normal glance.

I think it is a really exciting time to be involved with home 3D printing: Low (industrial standard) layer heights, fast speeds and multi filament printing.
Can it get any better? I'm hoping so

Hope this reads OK I can't see my entire post.

Kind regards

Paul

P.S. Yes I defiantly do mean 0.02 mm i.e. one tenth of the new Mark 7 extruders advertised normal layer height of 0.20 mm

At my age anything below 0.2mm looks perfectly smooth!

What W/T do you use for 0.02mm layers and what nozzle diameter?

Edited 1 time(s). Last edit at 10/09/2011 03:25PM by nophead.

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[www.hydraraptor.blogspot.com]

Yeh I'm beginning to know the feeling

It's the standard 0.4 mm nozel, as for the WT that's part of the foreign language I was talking about.

My sincere apologies I have only ever used Netfabb (started my printing endevours at the end of July this year) so I don't have the experience for a proper skienforge conversation. I only joined in in the conversation because I was interested in the perimeter / skin coments.

Sort of feel a fraud considering the thread subject.

Paul

Heya Paul,

"W/T" is sorta skeinforge-talk for thread width.. It's the thread width divided by the thread thickness (aka: thread height). With thicker layers, this value is an important component of how strong an object is because a higher w/t ratio means more contact between threads on subsequent layers. That's a bit of an over-generalization and there's more to it than that but it's sorta close to true.

With the tiny, tiny layers you've been doing, thread width becomes less about how strong you want things and more about keeping in the range of widths that the nozzle is capable of doing.

This is sorta like I was saying above.. If you're going to dive into tiny layer heights, some experimentation to find the range ot minimum to maximum thread widths your nozzle can handle is important. Once you understand that range, the range of w/t values that are possible at a given layer height are just a matter of doing some easy math..

Edited 1 time(s). Last edit at 10/09/2011 05:01PM by Dave Durant.

Hi Dave

Thanks for your explanation, you did know that you officially hold the position of 'my' printing oracle (not a paid position sorry).

The next few days I'm working the other end of the layer height profiles (shudder).

Still for me there is always stuff to learn and nice people to learn it from in this community. I am so pleased I stumbled across the Bristol University reprap YouTube clip all those months ago.


Kind regards

Paul

There must be some way to tell us what the thread width is generated by netfabb for .02, .04, .08mm layers.

Also, how do you level the bed to that accuracy for the base?

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www.Fablicator.com

> you did know that you officially hold the position of 'my' printing oracle (not a paid position sorry).

LOL.. I'm just parroting stuff I learned from people like nophead.. You should not pay him instead!

I will most likely shed more confusion or doubt to this thread, but I would say that we're printing with a W/T of 20 with Paul's latest 20micron Netfabb profiles.

Currently beta tested settings:
- Layer height: 0.02mm / 20 microns
- "Fine width" set to 0.4mm / 400 microns within Netfabb
--> W/T = Width over Thickness = 0.4mm / 0.02mm = 20

Is that math right? I know this number sounds ridiculously high to SF users, but that's what we're dealing with the Ultimaker at the moment (in beta testing). Released as default profiles are currently:

Format: Profile name / Layer height / Smallest width / Width over Thickness
- Standard / 0.075mm / 0.4mm / 5.33
- High / 0.06mm / 0.4mm / 6.66
- Ultra / 0.04mm / 0.4mm / 10

Note: Layer height numbers always refer here to the used half layer setting for perimeter lines. I know it's quite naive to contradict Dave, but I wouldn't call this "cheating", as it's the real deal: A plain and simple Z-step, which you could easily use for the whole print (give you have the time to wait another couple of hours ).

@Andrew: I think I can speak for Paul, too: Beds are leveled in all four corners to touch the nozzle. By the spring construction of the print bed there's a small play possible. Prints start at almost full contact (scratching the blue tape). First layers are barley visible. I caught this quite visually here: http://wiki.ultimaker.com/File:Ultra_first_layer_top.jpg

@Sublime: To get back to the original topic --> "Can you still print over hangs?"
I would say the lower the layer height, the better you can print overhangs from my experience. For me this is quite logic because you have less overhang to tackle per layer up if you split a given model in more and more tiny layers. Does that make sense?

BTW: REALLY like your recent Thingiverse prints.

Cheers,
Florian

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www.techwall.net

flouSH Wrote:
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> Is that math right?

Looks right to me. Between that and the other numbers, it seems like you're targetting (on purpose or by coincidence) a thread width that's the same as the nozzle diameter.

> I know it's quite naive to contradict Dave, but I wouldn't call this "cheating"

Er... No - it's not naive at all! I'm just one guy with one set of opinions. If I had a dollar for every time I'd been wrong, I'd have enough money to not care about being wrong anymore.

> Please provide pictures if possible.

Possibly not what you're looking for but: [davedurant.wordpress.com]

Most of these are from netfabb, not SF+repg, but I think I know how to do most of this in SF.. Are there any outstanding questions on this stuff? Have you tried turning your layer height way down???

I'm also quite new at 3D printing and RepRap and I use SFact, problem is I cant seem to get the layer height 0.10 mm, I take it that's just part of the limitations of the particular program or am I just doing it wrong and this feature isn't in the "Carve" window.

Also, how can a nozzel create an accurate stream of plastic that has a smaller diameter than the nozzel itself? Does it actually 'stretch' the plastic or just squish it against the build plate when extruding, or is it something completly different?

Gattling Wrote:
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> Also, how can a nozzel create an accurate stream
> of plastic that has a smaller diameter than the
> nozzel itself?

Layer height is a vertical thing, nozzle diameter is a horizontal thing..

Could you take, say, a fire hose and put it 1mm above the ground and have it work? Sure, as long as the pressure wasn't turned way up.

That seems logical. I kept thinking that for a smaller layer height you needed a smaller nozzel to extrude plastic thinner.
Hopefully I can mess around with the SFact settings a bit more and find the right one to give my figurines better detail.

Yes you need a smaller nozzle for more horizontal detail, but not vertical.

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[www.hydraraptor.blogspot.com]

nophead Wrote:
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> Yes you need a smaller nozzle for more horizontal
> detail, but not vertical.

Exactly right.
I've seen incredible prints on the Ultimaker with a 0.4mm nozzle and a 0.02mm (!) layer height.

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Yah, I saw those pictures too, and I was curious about how such a large nozzel could do such a thing.
It's funny how enlightened I feel now, not to mention how much better my parts look from a layer height of 0.31 mm to just 0.2 mm. I still kept the same feed rate of around 60 mm/s (I think, this is just off the top of my head). Not to mention how much better my printer can now withstand overhang and bridging without ending up with a droopy 'hairy' mess.
The only 'real' limiting factor at the moment is time, because my mother doesn't like me sitting at the kitchen table with this thing on for five hours straight. :p

a bit o/t, but I was thinking that with a almost- smooth .02 layer height, a very quick acetone bath might be enough to remove any trace of 3d printing.

As far as I've read, acetone baths often end up distorting a print because you have to soak it too long in order to remove the layer bumpiness.