Slic3r - Advanced perimeter tuning - 3D Printing tutorial

Sometimes you need to have more control over the way your 3D printer wants to print an object. This tutorial provides an example of how to change and optimise perimeter widths, to make the most of part strength or surface finish. I'll also give some examples of output Gcode and point out what to look for in selecting 'good' 3D printing tool-paths.

For this tutorial we are using Slic3r Version 1.1.7, but any recent version has the same ability to manually define the width of a printed perimeter.

Slic3r, Cura, Simply3D, Craftware and other applications 'slice up' our 3D model and converts it into layer-by-layer Gcode (instructions a 3D printer can understand). For any 3D printer that uses a filament (FFF/FDM) to create a model, it's quite important how the gcode instructions are sequenced, and also what order each section of every layer is printed.

Slicing programs are constantly evolving better algorithms to do a smarter job of model and tool-path creation, but most will not always produce an optimal print path for every type of model, or 3D printer configuration.

I documented this tutorial after experimenting with a new material that had some particular properties causing material expansion (oozing). I wanted to make a very clean printed tool-path as the object was a set of herringbone gears that needed to mesh well with each other. After doing a test 'slice' it was clear that some manual settings were required to print the object how I wanted.

Herringbone Extruder Gear set - Printed with a special PLA+Kevlar+PTFE composite material 

The new Colorfabb material - is a Kevlar+PTFE composite material mix that is so slippery it shoots out the nozzle and has some tendency to ooze. I wanted to test wear resistance so an ideal object was a set of printed herringbone extruder gears. I'm not sure if/when Colorfabb will release this material, but if you get hold of any I suggest an extrusion temperature of only 155 Degrees C, this dramatically reduced ooze and helps to get really clean prints, if you also take the advice in this tutorial.

I almost always look at the output gcode produced by a slicing program before I hit print. Quite often I will adjust the settings after looking at the print path, and also how the material was planning to print out for certain aspects or features of the model.

For viewing the output gcode tool-paths I use Repetier-Host. It generates a clear way to visualize the plastic filament per layer, and also the movement path the extruder hot-end will take, to complete each layer. This is really useful to get an idea how a model will be printed on your machine. It also gives you an approximate print time, so again this is useful to compare print settings with gcode output and print time.

For this tutorial we are going to be using the Advanced tab under Print Settings, see below.

As standard, Slic3r defaults to automatic extrusion width for all tool paths, apart from the first layer width. This is made twice as wide in an attempt to get the first layer to stick, and also to reduce time as the first is almost always printed more slowly than subsequent layers. Having a 200% increase in first layer width is also not always a good thing, especially if you need fine feature detail from the very first layer or want a nicer looking base.

After slicing your model with the standard automatic settings above, take a look at what extrusion widths Slic3r automatically selected for you. You can do this by opening the .gcode file in almost any text editor or by loading it into Repetier-Host.

This is just an example below - your numbers will be different and depend on the version of Slic3r.

; generated by Slic3r 1.0.1 on 2014-10-11 at 19:03:23

; layer_height = 0.25
; perimeters = 2
; top_solid_layers = 4
; bottom_solid_layers = 3
; fill_density = 0.45
; perimeter_speed = 75
; infill_speed = 80
; travel_speed = 320
; nozzle_diameter = 0.58
; filament_diameter = 2.88
; extrusion_multiplier = 1
; perimeters extrusion width = 0.58mm
; infill extrusion width = 1.18mm
; solid infill extrusion width = 1.02mm
; top infill extrusion width = 1.02mm

You will see at the top of the file a set of parameters, some you entered or selected and many of the widths Slic3r selected for you.

This guide is a focus on perimeters, but it equally applies to any other aspect of the printed line width (infill, first layer, top, support material etc.) With many objects, by specifying exact widths of printed perimeters you can get cleaner and stronger printed objects.

Slic3r uses automatic calculation if set to '0'

For the purposes of this tutorial my 3D Printer nozzle size is 0.58mm and the selected layer height is 0.2mm - I have previously tuned the top solid and first layer extrusion width. I also leave others to default '0' (automatic) settings.

In this tutorial the only thing we will be altering is the perimeter width from the default '0' (shown above), all other settings stay exactly the same so you can see the impact one change has on the resultant print-tool-path.

As standard Slic3r decided the best width of extruded filament to use from the nozzle size and the layer height you entered in the basic information about your 3D Printer. For printing at different layer heights Slic3r will adjust automatically but sometimes the automatic width produces an output tool-path that's not ideal, lets look at an example below.

When I sliced (with Slic3r Version 1.1.7) my usual herringbone gear set and looked at the output gcode using Repieter-Host. I noticed that it was attempting to do a lot of little infill lines and also had only part perimeters where I wanted as many solid perimeters as possible.

Slic3r (and most other gcode engines) give you a level of control over how wide or fine each extruded line is, for a given layer height.

In all images below we will view exactly the same layer of the model or stack of layers, this way we can compare exactly what the Slic3r perimeter width setting is doing to our print-tool-path.

Fig 1 - Shows in blue how the plastic material will be deposited for Layer 25 of our model. This gear is quite small, diameter across from tooth-to-tooth is about 18mm.

Fig 2 - Shows a close up of the same layer and path, lets take a closer look at what this is telling us.

The green line is the path that the extruder nozzle will take to draw (deposit) the material on this layer. As you can see above, the nozzle jumps across each gear tooth to fill-in a tiny square in every tooth. It also has a section of short fills in one of the middle layers for no obvious reason other than it calculated that the material could not fit. A series of short gaps were required so as not to pack-in too much material.

If this model was printed using the Fig 2 gcode, especially with any material that's prone to expansion, oozing or foaming (like the new Polymakr - Polywood, for example) it will most likely have wisps of material between the teeth and not be a very clean print. You can alter other Slic3r settings to limit crossing of perimeters, but for many other reasons, it's just too hard to combat every issue just by altering other settings, like retraction or sequence of printing. Manually tweaking the perimeter width gives a lot of control. 

With printed gears it's a good idea to have a high level of infill and also many perimeters to add strength to the outer surface. If you can't do many outer perimeters because of a small teeth (features) - like out small gear above, then a fatter single perimeter is often better (and stronger) than a thin wall and a blob of infill.

Skipping forwards, below in Fig 3a - shows a comparison of the first 25 layers sliced with an automatic (0.58mm) perimeter and also a tuned 0.86mm perimeter.

On the left (0.86mm) machine movements are kept inside the gear teeth and the overall number of movements and extruder retractions is dramatically reduced.

Fig 3B - Above is a side view of the first 25 layers, this shows clearly how the wider perimeter produces a cleaner tool-path for the model print.

But how and why did I select 0.86mm as the ideal width? - well that still requires some trial and experimentation. You can't just guess as the next set of images below will show.  

As Fig 4 above shows,  Slic3r often does things that are not always expected, so you do need to test various widths before deciding on a suitable fit for the model you are going to print.

Analysis of each Fig 4 - image - 

Above we can see various perimeter widths (using the same model layer to compare).

0.6mm = Is almost ideal, but has a bigger gap between inner perimeters and outer, this can produce unconnected walls and a weaker part - this can sometimes also be fixed by changing the level of infill.

0.70mm = Inconsistent sections of infill and many travel / retraction moves, not ideal.

0.80mm = Jumps between gear teeth with travel moves and inconsistent infill, don't use.

0.82mm = Similar issues but now the infill is consistent and equally spaced.

0.84mm = Still has infill in the teeth and a jump across each tooth.

0.86mm = Perfect! - this has equally spaced infill and a single strong perimeter that will be fixed very well to the inner infill. Very few travel moves and almost no retraction.

0.88mm = Just 0.2mm more and we have inconsistent infill and gaps.

0.90mm = This will produce a tiny gap between the inner two and outer two perimeters and a weaker part than the 0.86mm.

The printed small gear using 0.86mm perimeter is strong, clean and will wear well in use.

Don't assume that selecting a bigger width is correct or will always improve things, often going smaller is also valid, especially for bigger parts.

I usually start tuning by selecting wider than default widths as they will reduce printing time, but if that's not working for your model, then go thinner.

As an example the matching larger herringbone gear (shown below) was perfect at the Slic3r Default (0.58mm) setting and also at a width of 0.90mm, everything in between was less than ideal.

Both 0.58mm and 0.9mm would print well. For a material like the Colorfabb Kevlar+PTFE composite that expands on extrusion, the 0.90mm was ideal because it's depositing material quicker with less movement and has solid circular infill.

I first printed (Fig 5 - above) to show how the unequally spaced infill shown in the 0.82mm image looks when printed - here you have a gap between inner and outer perimeters. The gear is considerably springy due both inner and outer perimeters not being joined. I'm sure there may be applications when you would actually want a springy gear, but not this time.

Next the printed plate of four large gears in PLA using the 0.58mm default.

Fig 6 - Shows a close-up (during half the print) of the 0.58mm print, showing three very neat and solid inner and outer perimeters joined well. This will give an ideal 3D Print for this object.

You can also see that all the other widths have various issues we have already seen, so don't use.

- Summary and general tips and tricks - 

As a general guide for most prints I tend to use a 0.5mm or 0.6mm  nozzle at 0.2mm layer height.

With low layer heights it is possible to make the width of a line smaller than the nozzle size, but that's not really always recommended.

It's more common to have a scale factor of around 1.5x the nozzle size for line width.

For example a 0.5mm nozzle will extrude correctly with a layer height between 0.1mm to 0.4mm layers. You can go for an even smaller layer height if desired, but balance that with time to print and final quality.

Some materials can be used with a ratio of almost 1:1 for nozzle width. For example PET materials like Taulman Tglase and Colorfabb_XT will benefit optically from thick layers that are not too squashed.

And for the maximum width, it's usually good to stick to under 2.2x the nozzle size.

It's always a good idea to look at the output Gcode that Slic3r generates, even if this is only once to see what sizes of line widths it has decided, if you leave the advanced settings as automatic (0)

As another example when generating spiral vase (single walled perimeter) prints I often see people leaving the default size for perimeter, that's fine but it often ends up with a delicate thin walled object, when really a fatter wall would be much more robust for handling the object after printing.

Instead of a 0.6mm perimeter you'll be amazed how well a 1.2mm or 1.4mm thick perimeter feels and looks to a finished 'spiral vase' object. It almost always makes the print more useful too.

I'm a big fan of bigger nozzles, I often print with a 0.8mm or even a 1.2mm nozzle especially with bigger objects. You can still get a lot of detail and a fine finish even with a bigger nozzle. Just make sure you have an extruder drive that can keep up with material flow demand, or slow down.

If you get a chance, do try this out where appropriate, tuning of width is still not yet an automatic feature in slicers so until we have more auto-intelligence, doing it by hand can give some very impressive results.


Slic3r Reference -
Slic3r is an open-source 3D model to Gcode converter (slicer), it's main author is Alessandro Ranellucci with contributions from the 3D Printing community. You can find out more about Slic3r and download it from Here.

Slic3r is licensed under the GNU Affero General Public License, version 3

The Slic3r icon was designed by Corey Daniels



I hope you found that of some use.

Did you read it all? - too long? complicated? not enough examples? or just right :)

Remember to give me some feedback, It's always good to know if this sort of post helps.

If you would like to see more tutorials and 3D Printing advice, do let me know. Especially if you have a specific area or focus, either materials, methods or on design etc. Leave a comment below, or catch me on Twitter @RichRap3D or Google+ Here


And a little late, but Happy New Year everyone - until next time.

Rich.

TCTShow 2013 RepRap 3D printing - Community Hub and Show review

Hi Everyone,

We are back from the biggest Additive Manufacturing show in the UK and I must say it was absolutely fantastic!

The TCTShow has been running here in the UK for 18 years, and I have attended the last 8, this year however was the very best so far, the show organizers had not only opened up the show to much more of the 3D printing, maker and designer communities, but they really stepped up with a  massive presentation stage seating 400, recording of all the fantastic industry speakers during the two days and a great collection of 3D printed designer objects on display at the front of the show.

The whole event was bigger, better and had a real buzz. Indications even before the doors opened pointed to this being a really busy show, by 4:30PM on the first day it was still packed with visitors. Normally after the 3:00PM parking validation you see a mass exodus from these sort of 'industry' trade shows. This year it was quite different with a wide mix of individuals and companies representing all avenues and niche's of the Additive Manufacturing industry.

And if anyone out there is interested to hear more about any of the things I mentioned in my presentation, do let me know. One rather stunning project I talked about was nothing to do with 3D printing but is another amazing example of what makers and inventors get up to in their spare time, that was the Fusioneer project by Dr. Jonathan Howard - this is basically a self made fusion reactor! If you have time, do take a look at the 20min Documentary on his 3 year project here.

This post is just a taster of the event, you will find a full review of the TCTShow in the next issue (3) of the RepRap Magazine. We will also have the results of the Issue 2 Print for Life Competition and lots of other great stuff too.

After a busy set-up day we were all set for the show opening.

Within half an hour of the show being open we had a steady flow of people to the stand, by mid-day we were totally swamped with people, this continued all day and for the entire second day! We had quite a large stand compared to many others, but even this was no where near enough space as we were often 6 or more people deep and at times, we could not really get on or off of the stand, but that's great!. We were also lucky that an exhibitor opposite us had pulled out, so we ended up with some standing room for people waiting or just a way to get past! We would have blocked the corridors solid otherwise.

On the RepRap Community Hub stand we had -

The Team! - RepRap totally dominated the back section of the show - Photo by - Hamish Mead

RepRap Barcelona - The RepRapBCN team were fantastic, we all had a real blast from the moment they arrived carrying two stunning and solid new 3D printers to the end of the show, I can't wait to see them all again soon.

RepRap Barcelona have already made a great review video showing various aspects of the show, take a look below -

TCTShow review 2013 - Video by RepRap Barcelona

Faberdashery - Clare, Andrew and the team added magic, colour and style to our community stand, their unmistakable and rich coloured PLA was being used throughout the event, with stunning objects on display and fantastic advice for anyone who asked. I had my 3DR printer next to Faberdashery, and I just want to thank Clare and Andrew again for answering hundreds of questions about my machine while I was off the stand for one reason or another.

Think3DPrint3D - Tony and Roland had two of their very new Mendel90 Laser-Cut machines running. These machines have an optional enclosure that can really assist with big ABS prints. It was inspiring to hear how Tony and Roland have built up their business and they certainly have some very exciting things coming out soon.

NopBotShop - I was so delighted that both Chris and Mary from the NopBotShop could make the show, and also bring along the stunning black Di-bond Mendel90 that Chris (Nophead) designed and developed from scratch. Reading Chris's Hydraraptor Blog was one of the main reasons I became interested in doing RepRap development, so after all these years it was so nice to finally meet Chris and Mary.

Slic3r! - Another amazing person to meet was Alessandro, it was a true honor to meet up with Slic3r's creator, so many new and cool things are coming soon, it's going to be another great year for this fantastic piece of essential RepRap software.

RepRapPro Ltd. - The whole team were at the NEC this year! They also had so much to show that RepRapPro decided to take another stand right next door to us. This proved a very wise move due to the massive attention both our stands were drawing from the show's visitors. RepRapPro built up a Huxley from a kit on the community hub stand and demonstrated the entire range of machines and options on their stand.
Again, RepRapPro have some great developments in the pipeline, keep an eye out!

Active3D - Justin and the team from Active came fully tooled up with machines and a collection of more 3D printed things than I have seen in a long time. Justin described the event - "As good as a family Christmas! Thank you, Amazing" - I totally agree.

Hamish Mead - Hamish is the inventor of the world's first open source time machine... OK, it's a watch, but a really, really stunning one, everything is fully designed from scratch, including all the electronics, hand-built and featuring a 3D printed case.

Photo and Tinka watch by Hamish Mead

RepRap Magazine - I had the total pleasure of meeting Paulo, our magazine editor for the first time, and Gary Hodgson (the creator of thing tracker, Githubiverse and loads of other great projects)

Richard Horne - (That's me!) - well, you know who I am, I had my 3DR and recent Prusa i3 build on display.

3DR was in full flow printing some simple pots using my ultra easy dual mixer hot-end. I didn't get time to print all that much else unfortunately.

It was really interesting, seeing so many big names under one roof and we also had a wide range of presentations and speakers to see during the two days.

It was truly great to meet Todd Grimm and Joris Peels, who both helped me relax a little and provided great advice before I went on stage to present in front of around 400 people. Both Todd and Joris have a wealth of experience in additive manufacturing and offered huge insight during the show and in their own presentations to a packed out crowd.

One presentation I wish I could say I will never forget was from Jeremy Pullin (@jezpullin), Jeremy is the Rapid manufacturing manager for Renishaw. I was not quite expecting such a spectacular display. It was very much like seeing a really good comedian on stage, but upon waking up the next day you remember that you had a great time but have forgotten all the jokes. I felt this way after Jeremy's presentation, and I'm still trying to recall now what was said. Maybe it was the shock, I was clearly not prepared. just to give you a taster - Jeremy started off by Glassing himself on the forehead live on stage, then attempted to kill someone on the front row with a scented candle! - after that, it was a bit of a blur, but a lot of extremely good points were raised. I'm sure the entire home 3D printing and maker community was directly insulted at one point with a reference to masturbating over the new Dr Who assistant...  It was all very good stuff and if it ever makes it onto the internet you may even be able to check out what you missed. As Duncan Wood quite rightly said - that will go down in legend!

Jeremy lives only a short distance from me, so I do hope one day to meet up with him over a pint and talk about some of the things we don't know about Additive Manufacturing, after all, we only make simple self-replicating machines here at RepRap ;)

Ultimaker! - We spent some time with the awesome Ultimaker crew, they were showing the new sparkling Ultimaker2 - all white and innocent :) - there was a rumor going around the show floor that their machine was fighting the (black and red) 'dark side' by using the good 'rebel force' (white and blue) of the new Ultimaker2 - I think it worked :)

The Ultimaker 2 Easter egg ! - play a spot of breakout while waiting for a print :)

Loads of other things to see and do at the show, but I'll save them for the next RepRap Magazine issue.

Lets just finish off by saying we had a lot of fun!

If you want to read more about the show, take a look at the TCTMagazine and Personalize.

You may have noticed a lack of comments about the bigger companies and 'professional' products, that's basically because very little has changed, both in the technology offering and the attitude towards licensing.

I was quite disappointed to see designs and models being used without any sort of attribution, but unfortunately not surprised. Many of the bigger players in this industry are still playing by different rules, and until that changes it's going to be hard to see how the communities, makers and designers can really collaborate with them. I'm still hopeful that things can change for the better, but regardless we are setting our own path.

Rachel Park covered wider aspects of the show in her recent article for 3DPI here - Well worth a read.

The RepRap and maker community already plan to be back bigger and better next year, the TCT Show is moving to a 3 day event, they have also signed up to be the 3D printing voice of CES (Consumer Electronics Show) in Vegas and London next year! - that's massive news.

If you want to take part in the TCTShow 2014, we are already making plans, with your help and support it could be really big, really, really big! - If you want to know more as soon as we do or wish to take part in next year's event, please e-mail me at tctshow@reprapmagazine.com and I will keep you updated.

Finally a really massive thank you to all the show organisers, Personalize, TCT Magazine and everyone who helped make this show a total success. Also not forgetting all the many people who visited us, shared ideas, failures and successes. It was great meeting each and every one of you.

The TCT and Personalize team at thought of everything, and I was rather pleased to receive this gift of appreciation for presenting at the show. From Hackerspace to Aerospace - you guys totally rock! - can't wait for next year.

RepRap really is a special project to be involved with and would not be the same without all it's fantastic and enthusiastic members!

Until next time, thank you.

Rich.    

And yes, I have not forgotten about 3DR part 3 - it'll be up soon :) Promise

Slic3r is Nicer - Part 3 - How low can you go?

This post is about printing small layers in Slic3r. It's Part 3 of my Slic3r Overview, I hope it's useful.

In Part 1 we setup some Slic3r settings and performed the important Extruder Setup
Part 2 looked at print speeds, filament dimensions, heated beds and did some basic printing.

After Neil Underwood's recent Blog post about ultra-small layers I decided I really needed to experiment, but I wanted to see and compare for myself at what layer height it was pointless to go lower. I didn't fancy messing about with getting my bet 'that' level so I made and sliced a simple object at many different layer heights and combined the Gcode so I could have one compare print.
This was printed at a constant speed of 50mm/Sec, it's just a double wall (1mm) triangle column, I could have changed speed for the different layers, but as a starting test I wanted to see what happened at a constant speed and ever lowering layers.

It all sounded so easy.... ultra low level printing is not at all as easy as it first seems.

Fine Layers Test 1 -

Slic3r Makes it easy to play with different layer heights, it's a good way to experiment and test if both your calibration and machine setup is really good.

Before I start a multi-hour print of something I wanted to make sure low layers would work and look good on my machine and be worth the time and trouble -

Here is a solid wall multi-layer simple triangular cylinder where the Gcode changes down in height every 10mm starting at 0.3mm (300 microns - my normal print height) going down to 0.04mm (40 microns) after that I stopped the print as something was clearly upsetting the surface of the print and making it lower quality.
I started to see 'bobbles' on the surface at the 0.05mm height, I first thought the temperature was too high, so I experimented with lowering it, that seemed to make the problem no better, maybe even worse as you can see below at 170/175 Deg C.

This was my very first very-low-layer print and I obviously it had some issues...

So I started thinking that because the hot nozzle is constantly going over the same plastic and causing constant re-melting of the surface maybe causing the effect seen below - for the want of a better way to describe it - 'heat-friction-bobbles' on the sides of the object. The white flecks are quite fine and many can be rubbed off.

I have increased brightness and contrast on this picture so it shows every flaw and defect.

For reference the print material in all these tests is Greenery Green PLA from Faberdashery, it's highly dimensionally accurate and is also very nice to photograph.

For reference - The test object printed at 0.3mm all the way up.

I decided to take a closer look at every layer height change under the microscope  - 

0.3mm flat face and corner.

 

At the 0.3mm to 0.2mm layer change point, interestingly Slic3r changed build direction of travel when the layer height change to 0.2mm, in the picture you can see the effect above.

0.1mm

0.05mm

0.04mm

Clearly things are getting worse as layer height decreases.

I had produced Gcode all the way down to 0.01mm, but I didn't print any lower for this test.

Could it be a calibration issue?, too much plastic? or maybe a mechanical limit?

The Z axis on this machine is set to 8x micro-stepping, using an M8 rod this gives 1280 motor steps per mm - 0.05mm is still 64 motor steps, so Z resolution should be good enough. 

Even though I'm also only using 8x micro-stepping on the extruder it's a Wade style geared design so also has plenty of steps to ensure plastic is flowing at a constant rate even with very small levels of plastic extrusion.

I was also concerned about my choice of test object, being a triangle with solid walls the point requires much less volume of plastic, and I started to think the corners were getting over-stuffed - I'm not sure how Slic3r calculates this compared to Skeinforge, but maybe performing this test again with a Cylinder or Octagon will shape object would help see if this is why I'm seeing this issue...

I was very tempted to publish the Blog post at this point and ask for help and advice, but I wanted to know why my machine setup was not looking able to do layer heights as low and as easily as Neil had achieved with Slic3r, so on with the testing.

I have never been very happy with using Springs on my print bed, recently I changed to very stiff ones and now with a glass bed I expected no more issues, but it was starting to worry me that the spring-bed could be causing my issues with low layer printing. - I tightened everything ad hard as I could get it (Still using springs) and tried again, the print was better but not significant enough.

Second thoughts - Could it be just the speed of extrusion? maybe the tiny amount of plastic does not have time to form a reliable bond to the layer below - the corner of the object (slower point) is notably more 'solid' and shiny at 0.04mm layer point. - It was time to change something and try again.

Fine Layers Test 2 -

Different shape object - Octagon test - 

In an attempt to rule out issues with my first Triangular test object I performed a similar test on an Octagon shape, this time starting at 0.2mm, then 0.1mm and 0.05mm and finally 0.025.

Here is how it came out - I have almost exactly the same problem again.

Close-up shows a similar result to the first Triangle tests and as I was printing this slightly faster (60mm/sec) than the triangle (50mm/sec) I was now getting more convinced that speed was the problem with really low layer heights. - Temperature could also be playing a part, but not quite as significant as speed.

With too much temperature (190) the very low layers (0.05 / 0.025) were practically printing by just extruder ooze, when you reduce the temperature to 175 the ooze is minimised and so the print quality also improves.

Niel's red pink panther lady did look a little 'furry' in the photo and with no compare or close-ups I was not sure if he had seen the same results as I had. Niel was using 1.75mm ABS, I'm using 3mm PLA, so I didn't expect to get to 0.01mm but I expected better results at 0.05mm and 0.025mm - time to investigate speed and temperature 'v' layer height.

After a few more test prints reducing the temperature to around 175 degrees is about optimal for layers lower than 0.1mm but you still need to reduce speed, see below. 

Better with reduction in temperature, but still much too fast for such a low layer height (0.025mm)

This was a final test to see if I could beat my extruder ooze by speeding up the print, I concluded that slowing down was actually the only solution for a clean print at layer heights below 0.05mm.

After reducing the speed to 30mm/sec finally the very low layer prints look good, I think that had finally cracked it - time to print something more interesting.

Fine Layers Test 3, Magic Fish -

Many of the very low layer prints I have seen (lots of stunning ones from Ultimaker users) are hollow sculptures or usually more vertical prints, I was very keen to try a low but highly domed print as these can be some of the hardest to print nicely and finer layers should make a big difference to the overall quality.

My selected object for the next test was the Magic Fish (Tovervisje) by bpijls this is a really nice part, a little tricky to print well, so a good test of lower layer printing.

7 test fish later I had a good set of settings to help print a low layers.

My Reference print @ 0.3mm / 65mm/sec

A few close-ups on the tail of the fish as this is an extreme area for both print bridge and overhang. 

(All these fish are printed with 25% infill)

Reference print -  standard 0.3mm layer height - very quick reasonable print.

0.2mm layers, 2 perimeters and only 2 solid layers (2 x 0.2 is not enough)

190 Degrees C and 60mm/sec Perimeter and 80mm/sec infill

At 0.1mm you need to reduce print speed, reduce print temperature and increase number of solid fill layers...

If you don't reduce speed and increase layers it will end up printing something like this above.

Internal infill still builds ok at 60mm/sec (see above) when at 0.1mm layer height, but at 40mm/sec solid layers also print well on top of loose infill at 0.1mm so again slower is better at low layer heights (below 0.1mm)

You need to experiment to get the number of solid layers and perimeters correct for the type of print you are trying to do, this is so much more critical at very low layer heights than with 'normal' printing.

0.1mm layers, 3 perimeters and 4 solid layers.

0.1mm Layers and 40mm/sec - Finally a nice looking fish, the only issue is the eye.

As these are the last few layers to print, Slic3r is not yet slowing down so dumps layers too fast - Slic3r will soon have the ability to limit minimum layer time so this issue should be eliminated.

I was just about getting sick of so many fish prints, but just one more - this time at 0.03mm layer height, I didn't note the build time, but it was well over 1 hour to print this little fish-  (30mm/sec perimeter and infill)

The first three layers of Gcode are done at 0.2mm to help get the build surface level, then it's two layers of 0.1mm and then all the rest at 30 microns (0.03mm layers).

At this layer height I could hardly see the extruder gear moving at all, you need to stare for many seconds to see it's actually extruding. - Higher gearing and 1.75mm filament should help and may also further increase quality for ultra fine layer printing.

I'm still not sure it's worth all the effort going below 0.1mm and I expect I will not go below 0.05mm very much if at all in the future. At least now I know to Slow down and reduce my temperature if I want to go under 0.1mm layers. - I'm really interested in your experiences with low layer printing, do leave a comment below.

Enough of the fish, I hope you give lower layers a try, it will certainly teach you a lot about your printer and among many other things test the quality of your printing material.

Future things to try - 

• ABS with very low layers
• 1.75mm Material
• A bigger Extruder gear ratio
• Low layers with Bowden extruders.
• Compare with Skinning in Skeinforge - I have only done a few so far to test the option.
• Test the new Version of Slic3r as soon as it's Released ! :)

Until next time, I hope you liked this Slic3r series, thanks for reading.

Rich.