Musings and Experiments on the Art and Science of 3D Printing

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Capricorn tubing - not the greatest thing since all-metal hot ends!

By Michael Hackney → Sunday, January 6, 2019
I'm continuing to commission and complete the details on my E3D tool changer printer. Over the weekend I calibrated all four tools (hot ends) for Z offset. In the process I printed a small part with each tool. I was aghast at the horrible parts I was observing. On all four tools yet. Something was not right. Was it a slicing issue? A firmware issue? Something wrong in setting up the tools?

The problem looked like typical filament starvation (usually due to an improperly set up extruder or hot end) with visible gaps in the perimeters and missing sections of infill. I know my slicers inside and out so after making sure I wasn't doing anything odd (KISSlicer) I was confident these artifacts weren't due to a slicing issue. I then thought maybe a bad configuration for filament advance in RepRapFirmware might be the culprit. The config.g was provided by E3D and has required some tweaking by us beta testers. But, after going through config.g with a fine tooth comb, I found nothing wrong.

The extruders are Bondtech BMGs and one of them has had some limited service, so I was very confident in it. There is virtually no way to misconfigure a BMG. The tools are E3D V6s. I've worked with E3D all metal hot ends since the v4 days and know how to set one up properly. Even so, maybe I might accidentally mess up one, but all four? Not a chance.

So, I followed my own advice and slowed things down and printed at 20mm/s while I carefully observed. The problem persisted at slow speed and I noticed that the filament "starving" happened at the start of a new segment after a previous one ended - i.e. it might be retract related. Retract was configured to .5mm for these test prints, that shouldn't be an issue. Once going, the filament flowed freely.

I scratched my head on this one. I took a hot end apart and tested by hand pushing filament - it was smooth as silk. I then removed the lever and spring from the Bondtech BMG and pushed filament through it, again smooth. Then I pushed filament through the bondtech up the 800mm of Capricorn tubing. That's when I felt a fair amount of resistance. With nothing else noticeably different, I swapped the Capricorn for normal PTFE tubing and the problem went away! I've done 2 tools now and tried 3 different filaments before and after and the problem IS the Capricorn tubing. Here are some photos.


This part printed with Capricorn was one of the better ones but it had large areas of missing infill and perimeter gaps. The ONLY difference between these two prints is Capricorn vs generic 2mm ID PTFE tubing for the Bowden. So I'm sitting on ~4 meters of Capricorn that is going into the rubbish. Can PTFE be recycled?

Mosaic Palette 2 - Understand and Control Color Bleeding

By Michael Hackney → Saturday, January 5, 2019

A print showing color bleed of red into the pearl white. Yuck!
Much better! Read on to learn how to get results like this.
I've been having a lot of fun with my Palette 2 over the last few months. By way of disclaimer, Mosaic gave me a P2 as a thank you for being a product tester over the last year or so. But, free or not, if a product doesn't live up to my high demands (and expectations) I will not endorse or promote it.

The P2 is a remarkable machine, completely redesigned from its predecessor, and capable of producing outstanding prints. However, like all things in life, a little understanding will go a long way to get the best results. One problem that new owners complain about - and usually mischaracterize as a splice calibration error - is color bleed. Splice calibration errors result in pure color being printed in the wrong place.

Look at this closeup photo of the salamander's head:

That light pink is not the same as the pure red in the eye. It is color bleed and really doesn't have much to do with the P2 at all - except that you can minimize or prevent it if you understand what causes it and do some quick experiments to refine transition tower tuning in Chroma or CANVAS (I highly recommend CANVAS - it is both a slicer and the Palette's magic software). This post will walk you through the color bleed tuning I've developed to achieve results like the second photo.

What is "bleed"?

First, some comments about why bleed happens. The simple answer is "we don't know exactly why it happens"! Bleed is not unique to Palette - it also affects multiple extrusion hot ends that merge two or more filaments through a single nozzle orifice like the E3D Cyclops. Practically speaking, the outgoing filament is not being completely purged by the incoming filament. That's the simple part to understand and adjust in Palette (or even Cyclops). However, some filaments seem to find hiding places somewhere in the hot end from which they bleed out at the most inopportune moments.

Years ago I noticed that every once in a great while, a streak of black PLA would creep into a light colored PLA print. In some cases, I had not printed black PLA for several prints! This black must have found some nook or cranny to hide in. We have some ideas on this but these can not explain all circumstances. More work and experiments are needed to improve our understanding. And through understanding comes superb prints!

In general, some types of filament bleed worse than others. ABS does not seem to be prone to a lot of bleeding. It does bleed, but is usually purged cleanly. PETG is another one that is not highly prone to bleeding. PLA seems to be the worse of the lot and certain colors like red and black bleed worse than other colors.

In theory, the new, incoming filament, should push the previous filament out the nozzle without leaving behind any remnants. This must not be happening, otherwise there would be no bleeding. So let's think about what's happing in practice.

  1. The filament is smaller diameter than the bore it is being pushed through. Even in the heater block area, the bore is larger than the unmelted filament diameter. The Palette works with 1.75mm (nominal) filament and the bores of most 1.75mm hot ends are actually 2.0mm. This leaves quite a bit of room between solid filament and the inner walls of the extrusion path. Perhaps molten outgoing filament can "circle back" and flow up and fill that space. Retracts - especially long 2mm retracts - might exacerbate the problem by pulling the outgoing filament up and around the cold incoming filament.
  2. The length of the melt zone increases the amount of molten filament. The more molten filament there is, the more trouble it can get into like filling voids and pushing up the extrusion path.
  3. The extrusion path may have hiding places. Consider the E3D V6 hot end. Its nozzle is tightened up against the end of the heat break. This could leave a little gap - especially if the edge of the bore is chamfered slightly. There may be other hiding places depending on the construction of the hot end. Also, the extrusion path may not be polished or slippery enough to keep molten filament from sticking to it. We already have some evidence that Chinese knock-off V6 "style" hot ends are not machined and polished to the same exacting tolerances as a true E3D hot end. Photos of the bore of the heat break looks like the surface of the moon. It's easy to imagine filament getting stuck and collecting in all of the grooves and scratches.
Here is a close up photo of a Chinese V6 heat break. This photo was taken by Bruce Jenkins (used with permission) and was posted on the Palette Facebook group as part of a conversation on bleed. You can clearly see the annular grooves in the bore waiting to trap and hold molten filament.

There are most likely are other contributors too. But let's look at these three categories and try to understand if there is anything we can do to improve the situation.

Case 1: space between the solid filament and the extrusion path

The extrusion path bore must be slightly larger than the filament diameter to accommodate differences in diameter from one filament to the next - or even within the same filament. It might be possible to reduce the bore to 1.85mm or so but that would require carefully monitoring your filament to make sure it doesn't cause a problem.

Some knowledgeable people have studied this problem in the past and one of them, Jetguy, referred me to some discussion on PTFE lined hot ends like the V6 Lite. The PTFE lining extends all the way to the nozzle and does several things: it's much slipperier than polished metal, it insulates the melt area to more localize the melt zone and as it heats it expands and decreases the inner bore diameter (because the outer diameter is constrained by the metal hot end. I am planning to do some direct comparison tests of V6 vs V6 Lite hot ends to test this.

Case 2: melt zone length


The length of the melt zone is primarily determined by the thickness of the heat block. So, shortening this block could result in less molten filament to bleed. Another contributor to the melt zone is the efficiency of the heat exchanger above the heat block. In an all metal hot end like the V6, the heat break helps minimize the flow of heat up into the exchanger but if you've ever had a heat exchanger fan die or disconnect, you'll know first hand that the filament will melt for a cm or more up into the exchanger. So, more efficient exchanger cooling could also minimize bleed. The most efficient cooling is water cooling. I've been an advocate of water cooling for many other reasons but it might also have a positive effect to minimize bleeding. Again, another experiment to conduct!

Case 3: extrusion path hiding places

Removing hiding places may be as simple as using a high quality hot end that's been machined and polished to precision or replacing inferior components like a heat break with a quality component. PTFE lined hot ends are certainly smoother than metal hot ends and worth conducting some experiments to see how they perform with respect to bleeding.

Now that we have a little better understanding of what causes bleed and some things that might contribute to it, there is still no guarantee that you can completely eliminate it. But don't despair, you can greatly improve your print quality with some simple tuning - color bleed tuning - as described next.

Color Bleed Tuning

To perform this tuning you'll need to download two models:

BleedTest-bottom.stl
BleedTest-top.stl

And it is best if you follow along using CANVAS. If you prefer to use Chroma and your favorite slicer, you'll have to translate the slicing parameters to your slicer.

Bleed Test Print


  1. Load both models into CANVAS and set the bottom part to the darker color and the upper part to the lighter color you want to test.
  2. Slice in Vase mode, DO NOT use a transition tower (select No handling).
  3. Slice with your standard layer height and extrusion width. Make note of extrusion width you'll need this later.
  4. Print the model.

Now, measure the the distance from the bottom of the part to an area where the upper lighter color is clean and not tinted. It is better to over measure a little than under measure. Make note of this height. (the example shows 12mm to very clean white).




Now some SIMPLE math:
  1. subtract 5mm from your measured height - this is your “clear height” in the formula
  2. calculate the transition length using your extrusion width and clear height using the following formula:

65.314 * extrusion width mm * (clear height mm - 5mm) = transition length

I found that this works great with a 20% transition but you need to have a well calibrated extruder, P2 and ability to precisely start the filament when initiating a print. If you need to maintain a 30% or 40% transition, you will likely need to increase the transition length by 10% or 20%, but this will get you in the ballpark. I am conducting further experiments and also working on studying the effect in various hot ends to test a hypothesis on where the bleeding derives.

PLEASE NOTE: this formula has been developed and tested with CANVAS with its integrated slicer. I am doing more research on Chroma and its supported slicers but some Facebook group members have had success with it on Chroma too.

The final step is to test your new transition settings by printing the model again, but this time enable the transition tower with your calculated Transition length.
  1. Load the model into CANVAS and set the bottom part to the darker color and the upper part to the lighter color.
  2. Slice in Vase mode, USE a transition tower (select Transition tower). Set your Transition length to the value calculated above and set Transition target to 20% (or 30% if you must).
  3. Slice with your standard layer height and extrusion width.
  4. Print the model. The top section should be clean with a crisp separation from the lower dark color.



It’s aaaallliiivvvveeee!

By Michael Hackney → Monday, December 31, 2018


First movement. Now it’s time for first print. All hot end heaters, bed heaters and fans working. No magic smoke released. Sensorless homing on X and Y working perfectly. It’s coming together fast now.

The E3D Tool Changer printer beta build

By Michael Hackney →

I have the good fortune to be one of the early betas (aka Guinea Pig) for E3D's amazing Tool Changer. At its heart, it is a CoreXY with an open front - which eliminates the one issue I have with Core XY format - you can't see it print clearly! This printer is not a "kit" in the sense that not all components are supplied. But the core (no pun intended) of the mechanical printer is included. The X-Y motion platform (Core XY) is fully assembled and ready to go as is the Z axis. The printer requires 7 stepper drivers so a Duet (Wifi or Ethernet) and a Duex2 or Duex5 board are required.

I was the second person to receive the overnight delivery from the UK (the first was in Europe). It came nicely packed in one large box. I got started putting it together immediately. The main printer frame went together in short order. The parts are beautifully machined and fit perfectly.

I chose to use four Bondtech BMG extruders (two normal, two mirrored are required) rather than the recommended E3D Titan. That's the only thing I deviated from the recommended build. What can I say. I love Bondtech extruders!

I didn't take a lot of photos of the build as E3D's site linked above has very clear and detailed photos of the printer. I wanted to get this beast built so I could calibrate and start exploring its capabilities.

In addition to the Tool Changer core, E3D will offer a wiring harness kit - which I highly recommend. Once installed it will look like this:
The "most challenging" part of the build was printing the required parts. I used SnoLab's Carbon Fiber PC+ as it is remarkably strong, high temperature resistant and looks fantastic. I did print a few parts in their Sublime Green PLA+. As I write this, I'm waiting for the last part to print that I overlooked. Of course it had to be literally the last step in the build - installing the IEC switch. I forgot to print the housing/bracket for it! It is 30 minutes from completion and then I'll be ready to commission the printer and get to work exploring its capabilities. Stay tuned!




Palette 2, SnoLabs Sublime Green PLA, E3D Scaffold filament and Gyro_the_Dodo_by_Virtox

By Michael Hackney → Sunday, December 30, 2018
This post has a long name to attract attention! I've been quiet for a few months - as I usually am during the last quarter of the year - because that is my crunch time for my EclecticAngler business. But I still do a lot of 3D printing research and printing during this time.

Earlier in the year I was selected as one of three alpha and beta testers for the Mosaic Palette 2 and have done a lot of testing, tuning and printing with it. After the beta period, Mosaic gave me a production Palette 2 to enjoy. And enjoy I have! This is my third Palette - I started with the original Palette, then the Palette+.  This new P2 is a COMPLETELY redesigned mechanism with an integrated scroll wheel and filament buffer and the amazing Splice Core - the heart of the splicing mechanism. And Mosaic has created a new Cloud service called CANVAS that integrates with their IoT (internet of things) device called Hub. CANVAS includes a slicer - notably, my favorite KISSlicer - and completely revolutionizes the Palette workflow.

I'll blog more about the Palette 2, CANVAS and Hub and how to achieve remarkable multi-material and multi-color results from them in the coming months. For now, let's just say I am literally blown away with what the Mosaic team accomplished. I'm well over 7000 splices with myP2 now without a single splice failure. That deserves repeating - over 7000 successful splices without a single failure!

Next up, my friends over at SnoLabs have been developing and bringing some remarkable filaments to the 3D printing community. Although they've just started, SnoLabs has made great progress bringing unique, beautiful, functional - and equally as important - affordable, high quality filaments to market. In addition to my now-favorite go-to filament for structural parts, Carbon Fiber - Polycarbonate+ - and including the amazing Sublime Green PLA+. Disclaimer - I do get a small royalty for each spool of Sublime Green to support my work and I greatly appreciate it. That said, what can I say, it is Sublime Green - my favorite color. Thank you SnoLabs!

I wanted to find a difficult project to show off the Palette 2 with its ability to splice different materials and Sublime Green PLA+. After a little googling, I came across a model I've known about for some time but never had the tools to attempt - Gyro_the_Dodo_by_Virtox. This model is a set of five nested dodecahedrons that independently rotate - all printed as a single print. Complex and persnickety, this model requires a well tuned extruder and printer and a soluble support structure. I choose E3D's Scaffold filament for the support.

A few quick tests to tune the splices on the Palette 2 ("cover off, 2-0-2") and I was ready to proceed. I sliced the model in CANVAS using my basic profile of 3 perimeters, 0.2mm layer height, 0.4mm extrusion width and .6mm top and bottom shells - other parameters are printer-specific. CANVAS automatically talks to your Hub and transfers the necessary g-code and palette-specific files to it. The Hub is Octoprint under the covers with special CANVAS and Palette plug-ins. Once the file has transferred, you print it from Octoprint exactly like you would print any g-code - except that Palette 2 will walk you through initializing and starting the print (more on this in a future video).

In the case of this Gyro_the_Dodo, Palette reports 473 splices required. My Palette 2 and printer are well-tuned and I've been playing the "how low can you go" on the transition tower size. This print was created with a remarkable 100mm transition length and 20% transition (I wish CANVAS would let me go below 20%, I think I could easily handle 15%!).

Without further adieu, here is the print in process, completed, physical support removed and the rest disked away by soaking in water...

About 60 splices into the print. The contrast go the Sublime Green PLA+
and Scaffold makes it easy to see what's going on.
About 175 splices in. Things are looking interesting at this point!
300 splices in, it's coming together - literally!
Here is the complete print - 473 splices, 34 hours and 13 minutes, 41.79 meters
of Sublime Green PLA+ and 45.48 of sacrificial Scaffold.
Here I've stripped away as much of the Scaffold as possible without risking damaging the part. From here, I soaked the part in one gallon of water for 30 minutes to soften up the Scaffold. I then ran the part under a stream of room temperature water - which washed away most of the surface support and allowed the nested dodecahedrons to pivot.
And here is the final product after soaking overnight, rinsing and drying.
I also printed a stand in SnoLabs CF PLA (black) to display it on.

A Strategy for Obtaining Great Prints

By Michael Hackney → Wednesday, August 1, 2018
I've published this Strategy on several forums over the past 4 years. It has been greatly expanded (content not number of strategies!) for my upcoming book but I wanted to share this here on my blog for my followers. Note that some of the information in this list is a bit dated, the updated version in my book is completely up to date and greatly expanded.

A Strategy for Obtaining Great 3D Prints

Like all new endeavors, there IS a learning curve with 3D printing. This is still the pioneering era for desktop printing and we are very fortunate to have such a great community here as well as other resources on the web. But the challenge with all the information out there is finding it when YOU need it and deciphering the many different opinions and practices - some of which are good and some of which are, well, let's just say "poppycock".

Another part of the challenge is there are many different means to the same end, but I assert that those who have developed a workable (AND reproducible) technique most likely took a disciplined approach rather than the shotgun approach of trying one thing after another. So, I thought it would be helpful to describe a method that you can use to 1) develop a reproducible approach to successfully printing the things you want and 2) improving the quality of your prints to meet your (realistic) expectations. Don't hesitate to join in or ask questions. As required, I'll consolidate any interesting information from follow-on posts into this initial post to help make everything easy to find.

Ready to go? Before we do, here is a little suggestion.

TIP: When you are starting a new print session, give the printer a little warm up exercise! Much like an athlete needs to warm up before a game, so does your printer! Don't just turn the printer on and start to print, turn it on and let the hot end get up to equilibrium, let the heated bed get up to temperature. I even like to print a quick part to make sure everything is up to temp, in equilibrium and working properly. It's quick and easy to do and can help eliminate a lot of problems.

#1 Get Experience. Start with the printer. This is more difficult than it seems because without experience, it is hard to know if you have a mechanical or electrical issue, slicing issue or if something else is going on. So, to that end, keep things simple until you have some experience. By "simple" I mean, don't print the Eiffel Tower model for your first print, print a simple, reproducible and small item many, Many, MANY times until you nail it. For me, I used the calibration cube. In retrospect, I should have picked something much simpler (see strategy #2). 

#2 Start Simple. We have a tendency to want to jump ahead to more complicated prints, faster printing, and bigger prints as quickly as possible. But a few hours spent working on a simple object or two will pay dividends. There are many aspects to successful 3D printing, everything from the printer (which in itself has a mechanical system, electronics system, hot end, extruder, heated bed, firmware), to the slicer (and all of the parameters available to control the slicing), to the filament itself, to the actual item being printed. With so many variables (100s, maybe 1000s of them) it is really important to pin down as many of them as you can. One very easy place to do this is with the model itself. Develop your experience printing the same model over and over until you nail it. Even with a simple model, you can (and should) approach printing it with a methodical approach from the ground up. That's the next strategy.

#3 Practice in Measures. I play guitar and was basically self taught. When I found new music to learn, I did what many untrained folks do and practiced the piece over and over again from beginning to end. If I made a mistake, I started over. Then, I took lessons from a trained musician. My very first lesson was worth every penny! My instructor watched me learn a piece and then said "you should Practice in Measures". What he meant by this was to learn the first measure (music is divided into small blocks of notes called measures which are small and relatively simple). Practice it until it is perfect. Then, practice the second measure until it's perfect. Next, combine the first and second measures until that is perfect. Continue in this way until you've learned all the measures and combinations of them. In complex pieces, there will be a few measures or sequences of measures where you need to put in a lot more practice.

The advantage of this approach, my instructor said, is that you are not wasting lots of time playing measures you already know. The practice of playing from the start until you reach a difficult spot and make a mistake is that you play, say, 30 seconds (or more) of music you already know to hit a 1 second spot you need to practice. So in a 30 minute practice session you are really only practicing what you need to practice for 1 minute! This completely changed my approach to practicing everything from guitar to 3D printing to machining to learning CAD, to ...

How does this apply to 3D printing? Easily! Start with a simple object to print and practice nailing the first layer. Too often folks will print a poor first layer and allow the print to continue. Why print on a bad foundation? You might be able to salvage the part but more times than not, it will peel from the bed or warp badly. Instead, nail that first layer. Once you have that perfected, move on to print the rest of the object. Once you have the entire object printed successfully, change slicing parameters to print faster, or at higher resolution and start over (nail the first layer, ...). Practice in measures.

I can't say enough about getting that first layer right, the subject of the next strategy.

#4 Nail the First Layer. I don't believe folks spend enough time learning to print a perfect first layer reliably. If there are defects in the first layer, they will invariably come back later to bite you later - the part separating form the build plate, warping, or a defect in the part. Print a good (or great) first layer is probably one of the most frustrating experiences for most, it is also the most critical. Here's where strategy #3 comes to play, don't continue a print on an inferior first layer! Abort the print and restart that first layer again and again until you nail it. Why waste time on a part that will most likely fail or not be useful? Each time you print a first layer, measure it! If you configure your slicer to print a 0.20mm first layer, then it should be pretty darn close to 0.20mm. If it isn't, you've identified a variable that you can easily fix and nail down (Z height). 0.20mm is not a lot and unless you have highly calibrated eyes, you can't tell the difference between 0.20 and 0.15mm, but your printer sure can. At 0.15mm the first layer is going to squish onto the print surface. It may even seem like you are getting a great first layer and great sticking (which you are) but later, you'll discover the part is nearly impossible to remove or your extruder will start making that all too familiar TICK, TICK, TICK sound from missing steps. A perfect first layer will go down smooth and consistently time after time.

TIP: polish the tip of your nozzle! Chared filament and scratches on the very tip of the nozzle are dragged over the layer as it moves around. Best case, these leave a visible mark on the print; worse case, they rip the first (or higher) layer off the build plate. 

#5 Slow Down. Back to my guitar lesson example... The other thing my instructor taught me in that first lesson was to practice slowly (using a metronome) until I nailed the measure(s) at a slow tempo. Then, gradually and consistently, increase the speed. The same applies to 3D printing, print slowly at first. This gives you time to observe what's going on (strategy #6) and just simplifies everything. I like to start new folks at 20 to 25mm/s print speeds. What's the hurry? If you print 10 aborted prints at 50mm/s what have you gained (or lost)? Printing slow helps all parts of the printer, from the mechanics to the extruder to the plastic filament coming out the nozzle, stay in balance or equilibrium. Fast movements can highlight mechanical issues, extrusion issues, etc. But when you are first starting out, you don't know how to identify and isolate these issues. In fact, even with all of my experience, if something starts to go wrong, I slow down. That removes a lot of variables and gives me a chance to see what's happening. I've identified everything from loose pulleys, to a stretch belt, to a worn joint on a delta printer arm! And, I've helped a lot of folks identify other issues simply by slowing down.

#6 Watch What's Happening. Especially in the early stages of learning, watch all aspects of the printer. Combined with strategy #5 you'll start to develop an appreciation for how the slicer does its magic, how the printer does its magic, and it is just simply fun to watch! I highly recommend putting a flag of some type on your extruder motor shaft so you can actually watch retracts and advances and watch the steady push of the filament. A piece of masking tape stuck to the shaft is fine or print one of the pointer models. Watch that first layer print, that's how you'll see if there is a problem and maybe even figure out why. For example, I noticed that the first layer wasn't sticking in the same spot on my build plate. Turns out that I had some potato chip grease there (don't ask)! A little wipe with isopropyl alcohol and I was back in business. Watch what happens when the layer fan comes on. Is it coming on too early and causing the part to peal from the print surface? Pay attention to the details of what's going on and then...

#7 Keep Notes. I can't stress how important it is to keep notes. I have a word processor file I add notes to as I go. In particular, I keep a section on the filaments I use and the detailed printing parameters for them (strategy #9). Perhaps I'm becoming forgetful in my advanced age but I don't like solving the same problem over and over again. If I keep a note about a problem and my solution, I can usually find it again pretty quickly. Once comment on notes, don't be afraid to purge! After a few years of doing this, my file got quite big. Recently I archived all of my H1 and H1-1 notes. I don't refer to them any longer so why keep them in my working notes?

#8 Be Consistent. A CEO friend I worked with many years ago was fond of saying "Consistency is the hobgoblin of small minds!". I understood what he was trying to say but it has to be taken into context. When you are first learning any new activity, it is critical to be consistent. If too many things are changing at once, you have no idea what contributed to a good or bad result. Don't change too many things at once. In fact, if you can isolate and change just ONE thing, you will have a much better chance of success and understanding. This isn't always possible so lock down as many things as you can. If after a run of successful printing you run into a problem, go back to a known good state (see #7 - you did keep notes on what this state was didn't you?) and start there. Many times we try to change too many things in our frustration and that almost always makes things worse. Step back and think about how to isolate the problem areas with as few changes as possible.

#9 Know Your Filament. This strategy is a little lower level than the previous eight but important and often overlooked. I see a lot of folks just assume that they should print filament X at temperature Z - for instance, print PLA at 200°C. This might get you in the ball park but if you really want to get consistent and GREAT results, profile your filament. It's easy and if you write it down (see #7) you'll never second guess how best to print that filament again. It's important to realize that higher temperatures are not always better, they can actually lead to issues - parts that are just a little too large, parts that stick to the bed too well and can't be removed, blobs on the print, stringing, and a host of other problems. In general, I like to print at the lowest temperature possible for PLA and ABS. Then, as I ramp up print speed, I also need to ramp up the hot end temp a little since the filament is not resident in the hot zone for as much time. I suspect little details like this cause people more problems than they might anticipate.

Here's how I profile a new filament:
  • Start with a reasonable target temperature - 200°C for PLA and 225°C for ABS (one quick note, it is ideal to have a calibrated hot end, so when I say 200°C I mean 200°C. One easy way to do this is to make a little table with the hot end set temperature (what you see on the temp display) and the measured temperature (with a thermocouple). Do this in 5°C increments from 160° to 240° C (or so). Keep this chart in your notes (#7) and you will always know what the actual temperature is.)
  • Now, use the manual controls of your host to extrude 50mm at 50mm/s and watch and listen.
  • If the filament extrudes nicely, reduce the temperature by 5°C and wait for the temperature to stabilize.
  • Test again by extruding 50mm at 50mm/s
  • Repeat until you reach a temperature where the filament does not extrude well. At 5°C to that temperature and note this as the "low extrusion temperature" for that filament. Use this low temperature whenever you are printing slowly (20-30mm/s). You might find some filament need to be bumped up a bit more than 5° so don't hesitate to experiment and find that lowest reliable extrusion temperature.
If you want to get really serious about profiling your filaments, do the melt-flow test at higher extrusion rates - 60 mm/s, then 70mm/s, etc.

Don't forget to measure the diameter of your filament too! Not all filaments are created equally. Measure in several locations to get a sense of variability. Most of the slicers let you enter filament diameter and they will calculate a reasonable flow for you.

Finally, once you've completed the filament profile, print the Simple Single Layer Test object in the Layer Tuning section at the end of this post. 

#10 Know Your Bedfellows. Probably one of the greatest mysteries in 3D printing is "the bed". Metaphorically, this is where the rubber (filament) meets the road (bed) and getting "it" right is absolutely critical to successful fused filament 3D printing. All sorts of folklore on bed materials, coatings, coverings, concoctions, and juju exists here and elsewhere on the internet. It is also one of the areas that there is no one right way to do it. If you have discovered a special incantation and bed preparation that works, by all means stick with it! But, for those of you struggling, here are some strategies you can use to make improvements. One comment before I begin...

I am VERY persnickety about the aesthetics of my 3D prints. My 3D printed fly fishing reel is seen from all sides and so it is important that the first layer is flawless and visually appealing. The photo below is the bottom surface (first layer) in both the outer teal ring and the inner white spool plate (you can see more of my work here). A perfect first layer finish is not required for all objects - consider the base of a Yoda or vase - but if you practice getting a great first layer on these non-critical pieces you'll be prepared when you need a visually perfect first layer on another project.

A number of factors affect adherence of the first printed layer to the bed. These include:
  • surface material
  • surface texture
  • surface treatment/coating
  • bed temperature and uniformity of temperature
  • air temperature
  • chemical bonding or cohesion
  • print speed (see #5)
  • filament temperature (see #9)
  • first layer height (see #4)
cleanliness (of bed and filament)
This isn't an exhaustive list but it does include the big hitters and, as you can see, there are a few of them so it is very important to take a methodical (#2 and #8) and documented (#7) approach when solving bed-related problems. This is also a place where careful observation (#6) can play an important part.

I'm not going to go through all of these in detail now but did want to comment about the last one - cleanliness. Whatever you do, make sure everything near and on your printer is clean and grease free. Silicone greases and lubricants are especially problematic since they are invisible and very difficult to remove. Keep them away from your machine.

Your fingers are a prime source of contaminants. Every time you touch the filament or bed, you risk leaving a greasy print (see my observation in #6) and these can (and will) cause issues. I try not to handle filament with my bare fingers, I use cotton gloves. If you use a plastic or rubber glove, make sure it isn't coated or powdered - we're trying to eliminate sources of contamination, not introduce them. On the occasions that I do handle filament with my bare hands I wash and dry them thoroughly first. This is one area that I think affects a lot of user's and is completely overlooked. How many times have you loaded filament right after eating chips? It introduces a big variable that can be difficult to track down, so develop good habits and eliminate contamination as a variable.

Your fingers can also leave contaminants on the bed when you remove a part or brush off stray filament strands. Don't touch the bed surface if at all possible. If you do, clean/degrease it with an appropriate cleaner. For uncoated surfaces like borosilicate glass, PEI, the various 3d party surfaces (PrintInZ and BuildTak), and films (window tint, Kapton) you can use isopropyl alcohol. I like to use the little packages of wipes as they are convenient and safe. You can also do a quick wipe of your fingers before tossing it in the trash. It is more difficult to deal with coatings like PVA glue, glue stick, and hairspray since these can't be cleaned. If you suspect a contaminated coating, your only recourse is to remove and reapply it. 

Finally, don't overlook filament storage, keep it clean too. I store mine in large zip lock bags to keep off dust. You can put packets of desiccant to help remove moisture in the bag too.

#11 Learn to Diagnose. 

Patient: "Dr. it hurts when I move my arm like this."
Doctor: "Then don't move your arm like that!"

The first point of this joke is, many people do the same thing over and over again without making any changes or stopping to think about what to change (see #8: remember, change one thing at a time) - as if just repeating the same print with the same parameters will magically solve the problem. It won't (see my footnote below).

The second point of the joke is that the doctor didn't attempt to actually determine why the patient's arm hurt, he just had him avoid the problem. I see that a lot too. Usually it takes the form of "I tried printing it with my red PLA and it failed but everything was fine with my blue PLA". There are many other variations on this (changing slicers for example).

Learn how to diagnose problems. This requires careful observation (#6). Once you've identified where the problem occurs (let's say getting the first layer to stick) then PRACTICE that piece (see #3) until you sort it out. No need to run through the entire process over and over. Isolate the problem, formulate a hypothesis on what you think might be happening and design a test to prove or disprove your hypothesis. If you see a problem and can't formulate a hypothesis THEN seek help! Or, pre-test your hypothesis here to get some experienced feedback. But, whatever you do, try to work through the diagnostic process yourself first, that's how you learn.

Footnote: Many years ago (20) my company had an annual laboratory safety week (I worked in a corporate R&D lab with lots of nasty stuff). One of the annual favorites was a gentleman from OSHA who talked about electrical safety. He started his presentation with a black and white video from the 1940s (I think) of a speaker walking up to a microphone on stage. The presentation was being filmed. The speaker reached up and grabbed the mic and was immediately thrown back and fell to the stage unconscious. Members of the audience rushed up to help him. This was all on video. As 4 or 5 people worked to help the victim, you see a gentleman casually walk up to the mic, reach out his hand and touch the mic. He was immediately thrown back and collapsed on the stage next to victim #1. Literally 30 seconds later a THIRD audience member walked up to the mic (now there are 2 victims on the stage and a hoard of people working to revive them) and carefully reached out his finger (looked like the scene from ET) and very, very gently touched the mic with just the tip of his finger. He was immediately thrown to the stage as the third victim. All of this was caught on video. No one died (we were told). Neither of the second two victims stopped to think about the problem, consequences or solutions.

#12 Be a Fanboy. I am probably going to lose some fans for this post about cooling fans!

Don't think of a part cooling fan as an object, instead, think about "air flow". If you need cooling on a PLA (or other material) part, then you need to understand air flow. Not all cooling fans are created equally. Consider this, some folks use a 40mm, some a 25mm, some (like me) a 25mm squirrel cage fan. Some are mounted to blow the full fan width stream at the nozzle area, some have a duct or some (like mine) have a very focused soda straw duct). So comments like "run your fan at 1/2 speed" are not specific enough to be useful information. Instead, you need to understand how your particular fan, it's arrangement, your material, etc, all relate to the air flow.

Using the previous strategies, try to minimize or eliminate the need for any sort of air cooling. Slowing a print down (#5) is one great way to do this. It also gives you a chance to see (#6) where any problem areas on a print might be. You can use this information to focus the right amount of air flow on the problematic areas. The tendency for many is to use as much air as possible. It is much better, more consistent, and more reliable to use as little air flow as necessary. This puts less thermal stress on the printed part.

When you do determine you have a problem that only a fan can solve, start conservatively. I also recommend using a duct of some sort to focus the air flow where you need it. Ideally, the fan would have the ability to follow the print nozzle and direct a small stream of air to the filament right after it is laid down. That is a difficult problem to solve, so most of us direct the air to area around and under the nozzle. But, by directing the air (duct) you can reduce the air flow significantly since it is now focused where you need it.

I suggest doing your own experiments and observations but start conservatively. I don't use a fan during the entire part. If you find you need to turn the fan on at full blast from no air flow, do it in stages so the hot end can equilibrate properly. You can do this manually, some slicers can support it, or it is easy enough to learn the simple "fan mcodes" to manually insert them where you need them in the gcode file (this is what I do for tricky parts). 

M107 is fan off
M106 S50 turns the fan on at 50% - the S parameter is the speed from 0 to 100

Using a focused air flow, lower air flow and the step up technique I just described, you won't see a significant drop in hot end temperature. PLA has an interesting property that if you change the extrusion temp at the hot end, it has a visible effect on surface sheen of the part from matte to gloss as you raise the temperature. RichRap has written an excellent post about how he uses this phenomenon when printing decorative vases. Although he was varying the hotend temperature, a similar effect can occur with improper air cooling.

I'm also an advocate of using off-platform cooling. By this I mean strategically placed (ducted) fans that direct air to problematic areas of a print. These can be mounted to your vertical columns or simply sat on the bed if it is not too hot. With ducting, you can reduce the air flow considerably and keep the cooling right on a "hot spot". This technique does require manual adjustment, repositioning, etc. But, it you are trying to print a really tricky part, it might be the only way to do it. Frankly, the part cooling capabilities of desktop 3D printers is extremely primitive at this point. It's fine for the majority of objects you might print but as we push the envelope on what's possible, part cooling is one area that needs some more work to automate it.

Consider this, the way I maintain very tight tolerances on the rotating spindle and hub assemblies on my fly fishing reels is to use a low beam of air cooling on the spindle as it's printed. This "locks" the filament in place in a very predictable way. Once I printed a few parts and measured them to make sure there was little variation, I incorporated that into the design to get exactly the tolerance these parts required.

Another Satisfying First Layer

By Michael Hackney → Saturday, April 21, 2018

This is the first layer for all nine parts for gzumwalt's air engine using four different slicing styles and supports with KISS' Lock Paths feature. Printed in purple SnoLabs PLA on an Ultibots stock D300 printer. This is this printer's last hurrah before being upgraded to carbon fiber ball cup arms, a direct drive Bondtech BMG extruder and V6 hot end and my Tusk part cooling shroud.
This is the model for my printing Contest #2 now underway.

3D Printing Contest #2

By Michael Hackney → Thursday, April 19, 2018
3D Print Contest #2 is open to all supporters and subscribers! If you are not a subscriber yet, please subscribe to my blog (here) and YouTube channels and you will be good to enter. Prizes for first and second place (see Prizes below).

THE MODEL

This very interesting air engine was just published by gzumwalt on Thingiverse: https://www.thingiverse.com/thing:2865030 and is perfect as a challenging print that will let you exercise your printing chops!

SCORING

The idea is to print it (including the propeller) and power it with a balloon! Entries will be judged on:

  1. 1 point for the total crowd scored score (see below) for aesthetics of the printed model - colors, print quality, etc 
  2. 20 points for "does it work powered with a balloon?"
  3. 10 points for each completed 30 seconds of run time on a single inflated balloon - no limit on the size of the balloon and a video must be submitted
From my research and calculations, a standard inflated balloon has about 800 mm of mercury pressure inside it. This is ~15 PSI. This model can be made to work on as little as 5 PSI so we should be able to make them work off balloon pressure.

PRIZES

SnoLabs.com has graceously donated the prizes for this Print Contest:
First place can choose either 1 roll of carbon fiber, or 2 rolls of other filament. 
Second place can choose 1 roll of any non-carbon fiber filament

RULES AND REGULATIONS

  1. Contest ends on Friday May 18 at 12 midnight EST, Participant scoring for category 1 must be complete by midnight on Wednesday May 23. Winner announced on Friday, May 25th
  2. One entry per person
  3. Submissions must include 1 to 3 clear photos and either the video or link to the video showing the full runtime duration
  4. Contest is open to all Patreon supporters who submit their entry in the contest_submissions Slack channel
  5. Contest is open to anyone who subscribes to both my Blog AND YouTube Channel who submit their entry via email to me at michael.hackney@sublimelayers.com and include your subscriber IDs on both the blog and YouTube, clear photos of your print (Limit to 3) and either the video or link to the video of the full duration run
  6. All entries must also participate in the scoring for category 1 (aesthetics). A photo of each entry will be posted on my blog with an identification number. Scorers pick the 3 prints they like best and email or message me with their choices ranked 1, 2 and 3. The total for each submission will be the number of points for Scoring category 1.
If you haven't subscribed to my blog and YouTube channel yet, please do so here:
Let the contest begin!