foehnsturm

To be honest, I was too lazy to find out if this has been discussed already somewhere. Like others I try to avoid infills as they are time consuming and don't add much strength to the part. Main reason for using them is to provide some substructure for large top surfaces. I don't like the small "enforcement" zig-zag infills close to slanted walls very much either. When not printed very slowly the corners tend to curl up, giving a quite rough surface which may cause additional trouble. And I don't like the additional retractions caused by infills. Less retractions are always better. So why not add an additional innermost perimeter line that oscillates inwards (in direction of the path normal) instead of infills? Amplitude and frequency should be adjustable. With high amplitude it would provide support for top surfaces. It also adds structural strength because it is partially fused with the perimeter. With high frequency (and low amplitude) it would replace the enforcement infills for slanted walls. And there are no additional retractions. As the path follows the topology of the perimeter it should be as aligned to the layer beneath as the perimeter (... at least hoping that, I haven't studied maths ...). If calculations for smooth corners are too complex, sharp corners should work as well. Of course the oscillating would have to be clipped at certain places like tight bends.

Of course I'm fine with that. However, I have no details which I could send (and ask royalties for). Just look http://umforum.ultimaker.com/index.php?/topic/1611-fixing-pulley-innacuracy/?p=13534. There is just an empirically developed CNC program at workshop. Prices are mainly based on set-up costs and machine runtime per part, which is around 4 min on a CNC bush-type lathe.

I've only printed PLA, PLA/PHA and ColorFabb XT so far, with the bed set to 44 - 50 °C. Ambient temperature is some degrees lower. Currently am measuring the air temp with the built-in sensor in my anemometer. Of course it would be great to have a detailed temperature logging.

This originally started as a posting in the physics of cooling topic. As the idea seems to gain ground, I would like to start a new dedicated thread now. Step 1 - The basic idea: Throw away all the tiny cooling fans and use a crossflow fan to create a laminar air flow that covers the whole printing area Experiences so far: The huge laminar cooling air flow at +/- 1cm nozzle height provides more than enough cooling for small parts and for bridging. It acts also as an active cooling of the hotend's cold side New prospecting minimum and lightweight printhead designs are possible -> Nick's UBIS printhead Prints have no good (cooled) or bad (less cooled) sides More silent setup compared to numerous small fans Of course a thermal insulation for the heater block is required Step 2 - The basic idea: In combination with a heated bed create a heated chamber without a top cover using an air curtain instead. Experiences so far: Only some 10-20% thermal energy gets lost through the air curtain The fan creates an uniform ambient temperature within the chamber The area above the printhead (especially the bowden) stays cool Well-tempered "cooling" air works seems to work at least as well as cold air Even big (260 mm long) parts don't show any distortion, warping or corner lifting Second iteration, front cover still under construction:

It makes sense to look the history behind the idea of mounting the UBIS on an Ultimaker. It's more or less a logical next step for the http://umforum.ultimaker.com/index.php?/topic/2839-the-physics-of-cooling/?p=27363. If you keep mounting clunky fans to the printhead you loose most of the benefits due to the hotend's compact and lightweight design (dual extrusion setups may benefit anyway). The thermistor only requires a slightly changed firmware (new http://marlinbuilder.robotfuzz.com/) and adding a 4.7 kOhm resistor to the board. I soldered a connector there, so I can change back and forth without any soldering.

I can hear you Drayson ;-) Shouldn't be such a big problem, technically. But as far as I know it's not open source.

Not a true warping torture test, but once again I have to say this is the best setup I have ever used.

Just my two cents. At the beginning of every z-step there is a breakaway torque between z-screw and nut to overcome. Slow acceleration would increase the time until breakaway torque is reached and - within that time - transfer unwanted movement to the nut, causing some displacement in x/y/z. Fast acceleration will overcome the breakaway torque almost instantly and therefore transfer less unwanted movement to the nut / print bed.

Got one as well. Same as owen: Sent a message to printrbot and they put 3 in the store. Fortunately I checked my mails just in time. Hi Markus - Thanks for writing us. We do have a very limited stock of 3mm cermic hot ends and just put 3 in the store a few minutes ago. Since we do not use them often, there are not many more around. Please be sure to purchase one quickly as we cannot guarantee we can put more stock in again soon. Take care, Printrbot team

This year's Christmas present: Well, not entirely printed but also some laser cut aluminum, magnets, a high-power LED and some SMD electronics (oh dear, my eyes are getting old...). Automatically switches on when upright and lasts for 4 hours with rechargeable batteries.

This is the perfect alternative to the clunky printhead designs with numerous fans attached, which seem to be commonplace today! Low mass, perfect accessibility, no fans, no additional wiring, no fan vibrating ducts, no loose screws ... Crossflow cooling and this minimum printhead, I think this is what a bowden extruder is intended to work with. Anyone here, preferably in the U.S who's already in touch with printrbot, and could make an inquiry (perhaps for an omnibus order)? As far as I know there is an exclusive agreement between Carl Ubis and printrbot.

What I can say is that colors have a heavy influence. The two samples were printed with ColorFabb fluorescent green and yellow with the same settings. While yellow behaves almost like regular PLA, the green looks much more "liquid". columns 1 cm high, 0.1 mm layer height, 2 perimeter lines, 50 mm/s, temp on the lower end, but doesn't have much influence But in both cases the extrusion / pressure graph doesn't match with the nozzle movement very well. There is always to much pressure at the end of a path when the printhead stops and "waits" for retraction, while there is insufficient pressure after priming for a new path. You can see the round corners in the green part, especially at the corner where the path ends. And you can see the extrusion gap at the beginning of a path. It looks like the lower PLA/PHA viscosity doesn't forgive as big pressure changes as standard PLA. I would really appreciate having something like the Jetty-Kubicek-Newman (JKN) algorithm implemented as it addresses this issue. While regular PLA works quite well without that kind of fine tuning, my impression is that it would be very helpful in this case. It looks like the real pressure is always a little behind the actual requirements. Of course, you could go slower but that would mean curing the symptoms only.

Ouch! I should definitely start to build up a stock of some ready-to-use spare parts. This one of the most minimalistic printheads designs I've seen so far. After all I've heard about the all-metal hotends so far this might be an interesting alternative especially for printing PLA. However, it seems that UBIS hotends are sold exclusively via printrbot and the ceramic heater versions are hard to get. And it's hard to believe that the cartridge heater type shares the same properties (heat zone length).

Same with mine and with the SD card reader as well. But no real idea why, a loose contact or a less then optimum solder joint somewhere?

Yes, both times. It will become the lower half of a LED table light. When printed with regular PLA I didn't like the flat surface, therefore the wrinkles . But with the woodfil filament I printed the flat version as well: 0.2 mm layers are invisible (considerably smoother than the first print with 0.15 mm layers).

First print with ColorFabb's woodfill coarse Nozzle: 0.8 mm, 210-225°C, layer height: 0.15 mm, speed: 50 mm/s no post-processing Retraction was used the top 2 cm for printing the bore holes. Extrusion seems to become a little uneven then.

Thank you drayson. To all who asked (and didn't get a response so far): There will be another batch early next year. I have to order some 100 to get a reasonable price. I don't want to ask for a markup like Ultimaking but I have to control my financial risk. Therefore, I will start to ask for binding pre-orders in January.

A short video:

Very curious about your results Nick.

There are many suitable 12 V crossflow fans available (Ebay ..., Walmart). There are not ridiculously cheap, but you should be fine with $ 20-30. Like so many other items today, I suspect there are actually one or two Chinese manufacturers who supply the worldwide demand for a specific item. The EU X-Fan brand looks much like the US XScorpion brand. My fan is approx. 20 cm (8") long and 60x60 mm. You might consider the "air redirection angle" between inlet and outlet, I saw 180° (straight through) and 90° types. But actually mine has 135° which makes mounting a little tricky.

... I'm currently trying to make something like that out of isoplan (a heat insulation flat sheet material) but it's tricky.

Hi Nick, Happy to hear that. Nice to have another guy trying this setup. The active cooling for the non-heated parts of the hotend might even allow to use "actively" cooled hotends without the attached fan. And it is also good for the filament temperature inside the bowden tube. Months ago, my first attempt with a completely covered housing ended up in a mess, a giant plug inside the bowden tube because the PLA was reaching its glass transition temp there. The next step could be an aerodynamically optimized printhead design, including a wind shield (made of some heat resistant material). This would minimize the disturbance of the laminar air flow, as well as direct even more air to the nozzle.

Hi Owen, Yes, the tube setup was pretty good. But I didn't like the bulkiness of the bowden + cooling tube and those annoyingly loud radial fans. And there was another issue: Air orifices too far away from the nozzle lead to insufficient cooling. But if they are closer, sometimes the printhead and the cooling air flow simply move away to early / fast. As this depends heavily on the part geometry and slicer settings, there is virtually no optimum compromise. And, of course, I wanted to try the topless heated chamber approach.

Hi Nick, The fan is wired like the original, just see post 53 through 55 in this thread. The fan(motor) itself is virtually noiseless, you can hear the breeze but that's not annoying. I will do a short video, if I find the time. It just works so nicely that I even stopped using brim.

Indeed, as Ultimaker went for the 1st price in the "maximum print envelope with minimum footprint" competition there is almost no space for fans or ducts which provide more air flow. One motivation why I started thinking in that direction.