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Posts posted by tachyio

  1. Hi Folks!

    I suddenly have the rare-exception of proposing my own university final year project in material science! And yes, its going to be about 3D Printing...

    So I was wondering what to do my research on...when it occurred to me that my Ultimachine Filament was vastly superior to the stuff I got from Ultimaker (no offence, but my experience was better), and relatedly, Ultimaker Filament is vastly superior to the stuff a friend of mine gets from China...

    So that got me thinking, that in addition to quantifying extruder performance, its also really important to quantify filament properties and how that relates to 3D Printers.

    I've written a rather lengthy draft, and will send it along to the professor sometime this week. I'm wondering if any of you have other ideas, or feel that there are other more important research topics. I would like to contribute back to the community, so that's why I decided to ask all of you :)



    Why are some plastic filaments more suitable for 3D Printing than others?

    3D Printing Machines are precision devices which not only require accurate mechanical systems to function correctly but also plastic filament which has very uniform material property throughout its length.

    There is a need to properly identify and characterise the ideal properties of a plastic filament that is used for 3D Printing, in order to improve a 3D Printer Operator's experience.

    The Problem:

    3D Printers rely on their plastic filament having very uniform and predictable properties in order to function properly.

    Any change, for example in melting point or flow-rate, could damage a 3D Printer by causing 'cold extrusion' or cause printed objects to be weak 'under-extrusion', respectively.

    Few studies have been done to relate filament morphology to parameters that are important to 3D Printers. As a result, most 3D Printer operators are forced to learn via trial and error the optimum settings needed to use a particular plastic filament. These 'optimum settings' do vary between filament batches, but more widely amongst different manufacturers.

    These important parameters are:

    (1) Plastic Filament adhesion-strength to Heated Glass/PCB Platform versus Platform Temperature in relation to Filament Morphology

    Reason: How stable can the printed object adhere to the printing platform, and at what temperature is this adhesion strongest? Why do some filaments adhere better at lower temperatures and others at higher temperatures?

    (2) Extrusion Mass Flow Rate versus Extruder Temperature in relation to Filament Morphology

    Reason: How fast can a 'standard extruder' extrude a filament with respect to extruder temperature? This determines the speed of a 3D Printer, and consequently, how fine 3D Prints can be. Why do some filaments flow more easily than others?

    (3) Plastic Filament self-adhesion strength versus Extruder Temperature versus Extrusion Velocity in relation to Filament Morphology

    Reason: How strong is the final printed object? Does the object shear easily due to poor self-adhesion? What material phases contribute to the strength or weakness of the printed object? How do these material phases form in relation to extruder temperature/velocity? How does this compare to a standard injection moulded part?

    (4) Plastic Filament Melting Point in relation to Filament Morphology

    Reason: There is a need to identify the filament composition and relate this to the melting point of the material, in order to ensure that manufactured filament maintains a standard melting point. Currently varies from 180C to 260C.

    (5) Plastic Filament warping degree versus Platform Temperature in relation to Filament Morphology

    Reason: Part warpage is an on-going problem for the polymer industry, and 3D Printers are no exception. At too low/or high platform temperatures, 3D Printed Parts can warp causing structural instability. A short and simple study will be done to quantify the warpage versus temperature in relation to the filament morphology.

    (6) Plastic Filament Glass Transition Temperature in relation to Filament Morphology

    Reason: The Tg of printed parts is important as it determines their mechanical rigidity during everyday usage. There currently is no standardised Tg for plastic filaments, it varies widely from 45C to 65C, most likely due to non-uniform properties across the industry.

    Procedure (Very Brief):

    These (6) properties will be tested against PLA (Polylactic Acid) filament from different manufacturers, and adhesion and tensile tests as well as imaging of the material structure will be used to quantify the findings.

    The Aim:

    To identify the material properties which makes a plastic filament suitable for reliable and continuous 3D Printing.

  2. Wow! I haven't been back here in ages, got frustrated with my Ultimaker for a month, until I figured out these exact same problems:

    Getting plugs and frequent jamming, due to the Bowden slipping upwards, and having the melt-zone too close to the PEEK-Bowden Interface.

    I fixed it by using a new white clip I got from Ultimaker, hope it will hold for a while at least! And retraction has improved in Cura 12.07, using it on my Mac which is a plus.

    So I'm back in happy printing land. But yeah it's only a matter of time before the plug of doom or "kidney stone" as I call it, returns.

    I'm all for redesigning my nozzle now that I actually understand it completely haha.

    How about a design where the Bowden Tube goes into the Copper Tube?

    So the Bowden interface is right inside the hot zone, so no matter what, a plug will never form there.

    I'm also in favour of switching to 1.75mm filament, a friend of mine is trying that with his RepRap, and Bowden friction is greatly reduced due to the increased flexibility. The thicker 3mm filaments tend to get lots of rough edges once it passes through the knurled bolt, and this causes huge amounts of friction inside the bowden.

    In addition, 1.75mm filament is a lot easier to melt. So if it melts faster, maybe we don't have to be so worried about keeping a large buffer of molten plastic for fast-printing. Kinda like broadband, versus dial up - faster speed, less buffer time needed.

    The heat sink I feel is necessary for keeping the transition zone between the Melt Zone and Cold Zone narrow - in addition to a melt zone and cold zone, there is always a transition zone, and perhaps (speculation) this is where plugs are forming inside the Bowden - it's kinda melty-warm, not hot, (any temp above the glass transition temp of PLA of 60C will do it) so when enough force is applied the filament expands outwards forming a plug, which solidifies between/after prints.

    Perhaps this "plug" itself becomes a sort of insulator, so when you try to start the next print, it doesn't melt easily, as its within the transition zone, and not within the melt-zone exactly.



    This forum is sorely lacking a "wishlist" section where we can post what we would like improved in the next ultimaker iteration. This is why I have decided to make this post.

    After endless struggles with the nozzle/ bowden tube interaction and other features of the UM nozzle I would like to voice my opinion on what I think the next UM nozzle should be.

    1) Screw the bowden tube directly into the nozzle assembly. Pretty much everyone is having the "plug" problem, and there are way too many opportunities for that tube to slip upwards and allow the plug to form. Screwing it in solves that problem entirely, since the tube is no longer held by friction but by leverage (threads), which is much stronger.

    2) Smaller hot zone. One of the primary reasons why ooze is so hard to get rid of is the fact that the UM hot zone is too long. Molten plastic stays in the nozzle even after retraction and results in dripping. A shorter hot zone allows the retraction of filament to have more effect on the pressure at the nozzle tip.

    3) One-piece nozzle. The major reason for leaks is the fact that the nozzle itself is screwed into a brass tube which is screwed into a PEEK insulator, not to mention the bowden tube held on by sheer luck at the top. Too many joints result in too much leakage potential, so go with the J-head styled design and make the metal parts of the nozzle all one part.

    4) Thin-walled heat isolator. The arcol hot end has this. Basically, a portion of the heater barrel is turned down so the metal is very thin. This forms a bottleneck for the heat and prevents heat from spreading upwards towards the PEEK insulator. Yes it does make the nozzle a bit more fragile but I think controlling heat is very important. This also helps to make the hot zone smaller and thus makes retraction a bit more effective.

    5)Easily removable. I think it would be cool to be able to switch nozzles in and out. With a screw-on bowden tube this would not be hard. Just screw a short length of tube into the nozzle itself. A part at the top of the head assembly accepts this short tube and acts as a junction between the short tube and the long one coming from the filament feed. Since the junction is far away from the hot end no plugs can form there, and since the short tube is screwed into the nozzle, no plugs can form at that interface too even though no compression is applied to the short tube going into the nozzle. There's a gap between the short and long tubes (within the 'junction' part up top) which allows a tolerance in the length of short tube attached to the nozzle. The aluminum plate has U-shaped holes and fixing screws to allow the nozzle to be slid in sideways, etc.

    The nozzle and filament feed are two of the major areas where ultimaker needs to improve, so let's make sure this happens.

    What does everyone else think?

  3. Yes I do get this, which ones are the "set screws"?

    After moving into my friend's office, the machine is experiencing daily "thermal cycling" from 14C during the day to 29C at night, which I believe is causing it's belts to loosen and the frame to distort very slightly - which is affecting the quality of prints.

  4. Also I was struggling with reconfiguring Cura RC4 to work nicely with my Ultimaker, adjusting E-Steps, and fiddling with the new options, but I finally decided to turn off dwindle. Also with these frigid temperatures, I had to readjust the printing temperature and flow-rate, also printing slower helps a lot! It's still not super-stable software wise, but hanging in there. I might stick to RC2 for serious work.

    Dwindle should be off by default... and the defaults match RC2. There shouldn't be any real difference between an RC2 and RC4 slice with default settings.

    Hmm I am noticing strange behavior such as the top surfaces not being sealed, I did turn the "solid-infill for top" option in expert settings to ON. Also walls were too thick one time, and comb didn't appear to be working on one of the parts I printed; the Ultimaker would travel over a large empty section even though it was obvious a combed path was entirely possible :/

    I am doing a third print with Cura RC4 now, will post photos when its done. Hope it comes out okay, but I can see unsealed top surfaces.

  5. I am actually thinking of constructing a nicely sealed hot-box for my Ultimaker. I notice that a lot of professional printers are encased in a sealed enclosure of some kind. Now I'm assuming that the purpose is to maintain a nice, constant internal temperature for printing.

    Has anyone tried a hot-box? I think if I make one, I'll keep it around 50 Degrees C.

    I also have a Prusa Mendel coming along for handling large, crude bulk parts. We'll see how that goes...it looks...primitive, compared to the Ultimaker...no hobbed bolt, printed parts that are not all that accurate, etc.

  6. Sorry for the silence guys! I just moved into a horribly cold office room as my house was starting to get too small, temperatures in here average 14-16 degrees celsius...so struggling to get the heated bed working was taking up a lot of my time...After messing around with a few cheap china power supplies, I finally threw in the towel and invested in a laboratory power supply. It wasn't cheap about 350USD, but I know its rock-solid as I've used these before, and the best part is I CAN TUNE THE OUTPUT. I will probably use it to power something else in the future :p

    My funny voltage and current list:

    Normal Cold Day - 6V and 5.3A

    Cold Rainy Day - 6.3V and 5.6A

    Zomg, I am frigging DYING Cold DAY - 7V and 6.1A

    I usually keep the bed around 70 to 80 Degrees C, a bit on the high-side I know, but it works at these low temps.

    Printing is back to normal, though I think now my hobbed-bolt has worn-out and would need a replacement of some sort. I cleaned it twice, and still there is some skipping 5-10% of the time. I received my new hot-ends last week and finished installing and sealing up one of them, works great now, no more leaks and jams in there.

    Photos of the heated bed and the lab power supply...thanks for the info though, I might try the parallel thing sometime when I have another machine in here.



    Also I was struggling with reconfiguring Cura RC4 to work nicely with my Ultimaker, adjusting E-Steps, and fiddling with the new options, but I finally decided to turn off dwindle. Also with these frigid temperatures, I had to readjust the printing temperature and flow-rate, also printing slower helps a lot! It's still not super-stable software wise, but hanging in there. I might stick to RC2 for serious work.

  7. Hmm I flashed the firmware using a version of Marlin that supports a heated bed - using Daid's Marlin builder-


    But now I'm getting a host of other problems, like the Ulticontroller not being able to move the steppers around, heated bed temperature being reported incorrectly, etc.

    Hmm, I have both a 4.7kOhm and 100kOhm Thermistor at the moment, so trying to see which works best. Most threads say to use a 100kOhm Thermistor with a 4.7kOhm Resistor to form a 3-legged circuit - but I tried that and temperature reporting is still wonky.

    Now I'm just not sure...

  8. Wookay,

    I managed to get a nice PCB heated bed from my local RepRap dealer, there actually is a RepRap dealer in Singapore now. O.O

    Seems to me to be a 19V thing, so I guess I shall try to plug it into one of my v1.5.6 electronics board's green sockets. It actually says "heated bed" there.

    I plan to also get a 19V 400W power supply brick for my Ultimaker...or is it safe to run two 120W 19V power supplies in parallel to the Ultimaker? That way I get an additional 120W for the heated bed.

    My main issue though is that the kind dealer gave me a 100kOhm Thermistor, but the Ultimaker Add-On Wiki states that I will need a 4.7kOhm Thermistor.

    Is there a way to make a 100kOhm Thermistor behave like a 4.7kOhm one?

    Thanks guys :) I will post some photos of the tech that I got.

  9. Hey Daid,

    I used RC3 for a couple of prints and its looking good so far. Just a couple of issues though:

    1. When in the simple-mode, the z-tray moves extremely slowly, resulting in the primed extruder become unprimed as it drips its contents onto the stage before the print starts, so Layer 0 is basically not printed as there is no more PLA in the extruder head

    2. When I flip the models say along x, y, z, the flipped model ends up at the side of the build area rather than the center...is there a way to center it?

    3. Where did the options for duplicating objects go to? That was quite useful.

    But all in all, great job! The motor control functions are very handy, and slicing seems way faster than it was before =)

    Does Cura work with standard RepRaps such as the Prusa Mendel though? We are planning on building a Mendel to handle the larger bulk-parts, as well as parts which need minimal stringing - as the Ultimaker is great for small accurate parts but we experience huge warping issues for anything larger than 8cm.

  10. Have you tried Autodesk 123D Catch Beta? It's a Cloud-Based 3d scanner. It actually works quite well, though not as expected - it works better with lousy data than with good data. I think primarily because it was meant to be used by tourists shakily holding cameras and snapping off multiple views of the same object, haha! It's free too, I gave it a go over the weekend, and it seems to work about 75% of the time.


  11. Damnn, I'm so excited!! =)

    I just finished a couple of ultra-fine gear prints with Cura RC2! The spacing between those teeth is <1mm.

    Check it out:

    https://plus.google.com/photos/10422046 ... 7801200274

    I'll go download RC3 once I finish this batch of prints!

    Anyway just curious Daid, is there a way to decrease the Joris-Bump? I have Joris turned on in expert settings already, but the line still appears (see photograph, lower-left silver cylinder). I'm already superbly happy with my prints, so its just a niggling issue.

    Thanks so much! =)

    Oh yes, I also improved the X-Y accuracy by damping vibration of the Ultimaker (vibration is my biggest biggest enemy now). What I did was to add dumb-bell weights to the bottom of the Ultimaker. As a result, positioning is even better than ever, even at 0.2mm on a vertical, its hard to distinguish the layers now. In addition, I've added padded feet, and bought a special solid-wood table with rubber feet to place the printer on.

  12. Hmm I connected quite a long LED strip, removing now for fear of overheat. The light wasn't constant too and appeared to pulse in sync with the 12V fan current - I'm assuming the fan motor is pulsed to save energy, seems that way.

    More importantly, you mentioned there's a 19V terminal for a heated bed? I want to try printing in ABS as what little that I've printed looks awesomely smooth! Anyway for me to connect a HBP?

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