burki

Hello Daid, i have started this thread : http://umforum.ultimaker.com/index.php?/topic/4207-no-jam-extruder-idea/ that might be of interest to you: It's about measuring the pushing force the extruder is creating, to automatically adjust extrusion rates, for example if the filament diameters are less than ideal.

Thank you for the link, Johan. It seems this research does somehow at least support the iddea that measuring the force of the feeder should go in the right direction. While i am aware that i am of course in a case of confirmation bias, what do you folks think? Is this an idea worth pursuing?

Hmmm.. admittedly, the spring loaded mechanism, or even that strain gauge setup has the downside of too much travel. How about this: a fixture where the bowden tube goes in. this is loosely fitted in some sort of bearing, such that when the material is fed into the bowden, the fixture is pushed against the bearing. between the fixture and the bearing there's a pressure sensor. For example a flexiForce sensor. This would eliminate the travel / retract issue and still be fairly inexpensive, while the flexiForce sensor would provide the presure information. Is there a free analogue input on the arduino board? if so, total costs would be something like 20-30 Euros, since i assume that fixture and bearing should be easily printable. Now all we'd need would be one Daid :-) and some experimenting / calibrating.

Hm. i'm a bit torn... i know you guys are nnot hanging around lazily doing nothing, on the contrary, i assume. So, i don't want to be nagging you. Yet, about a week ago i ordered some Filament and an Ulti controller. According to the shop, it's paid and ready for a week now. And i really, really want that stuff! :-) I was wondering what's holding you back? Or if there's any hint on when you find the time to ship my order?

Is that a repeatable problem? Have you checked the layer view in Cura, to see if it's a problem in the gcode? Plus, you may want to tighten the grub screws in your pulleys.

Hello als, i confirm your brown and orange appear to be swapped, my order is green-orange-brown on temp 2. On the plug that goes on the print head my wires are also green-orange-brown. So as long as yours are parallel, you should be fine. Does that help you?

I was thinking that the springloaded mechanism should compress the spring by something like maybe 2 mm when operating correctly.. That would not affect retraction unduly, those 2 mm can easily be added to the retraction length. I still have the impression that such a mechanism would offer a fairly inexpensive and robust way of handling issues with irregular or badly measured filament diameters and clogged nozzles. I don't think i really understand your thought about a pressure sensitive pad. Could you explain that a bit more?

Good point... Yet: Speed and temperatures are known factors, at any given time, for the software. So whats missing is some sort of material constant. Compared to the filament diameter, that should be easier to acquire. So i assume that if we had a means to measure the pressure in the bowden tube, that should indeed improve matters ?

Fiddling with clogging and such, i was wonderning... If one took the existing extruder, and changed the extruder side of the bowden tube so that there would be a spring loaded fixture... With such a setup, if the extruder feeds too much material, the spring loaded mechanism would be pushed out of the extruder setup. If now we measured how far it is being pushed out, for example with a hall efect sensor, or even a cheap sharp infrared distance sensor or anything of the likes, it should be possible to tell the extruder to extrude less. when the spring is not compressed at all, while the extruder pushes material, we might tell it to extrude more. Thus we could ignore the filament diameter, and even handle varying diameters fairly easily. Even the problem with the first layer being too low, forcing too much material against the build plate and thus building up a filament jam should be a problem of the past. Obviously the firmware would need some tweaking for such a setup. What do you guys think?

I was thinking in a similar direction like you, Jonny. But i was considering having the current setup from the back (straight ros and threaded rod) on each of the sides (omitting the one on the back), and coupling the two units, for example with a timing belt. i guess only to have the straight rods and bearings will be counter-effective. Since the bed is still only supported on the back, the front is still free to move. This will imho lead to canting in the front bearings. If you had a rather stiff design, where two sides (or back and front) are controllled, you should be able to get a very rigid print bed. On the other hand, you might get decent enough results if the arms were a bit higher, so the bearings get longer, resulting in a better angle to get the forces on the brint bed into the bearings.

Drayson what kind of problems are you experiencing? I assume you let the glue dry before printing? As i described above, printing on glass/wood glue works liek a charm for me. It doesn^t even need to be 1/3, i use a _much_ thinner mixture, so it can easily be spread, just like water colours.

Hello LePaul, first: it seems large parts will warp, no matter what. You can reduce the warping though. Apparently the most effective way is having a heated bed, and/or heated build chamber. I personally have no heated bed yet. But i am printing on glass now instead of tape. The glass is covered in a thin layer of wood glue thinned with water (so thin it looks like water colours), applied with a soft paint brush. It needs to dry before printing, of course. I clamp the glass to the original acrylic build platform, so i can swap out the panes. Thus i can have panes prepared and just switch them without waiting when i want to do the next print, and can still use the original levelling screws. (You need glass panes 220mm * 240 mm, mine are cheap 2 mm thick from a DIY store, although thicker should be better) I have better adhesion to the glass/glue than i had to the blue tape, and less warping (not none, though, and for very large parts (200mm long), the corners still come off, but less so than they used to on the tape). Plus, i have mirror-like undersides of my printed parts. And finally, the printed parts almost pop off of their own after cooling. that's another up side of having several panes: You can take one out and leave it to cool, swap in the next and print on happily while the first one cools :-) Hope that helps you a bit?

Me too! I was already enthousiastic when i saw that the site was down for maintenance. But it seems you guys have forgotten to add the heated bed / buld platform upgrade to the shop! :-)

I would assume that even if the PLA softens in warm water, it should harden again when drying. Has anyone tested that yet? I can only test "by finger pressure feel" and did not notice problems with the parts i had submerged for a day or so. But i had not really paid any attention to this topic, so i will need to do a few "household" tests. Although if anyone has some reliable testig methods, i too would be interested in insights regarding that matter.

Interesting news! To answer the original question: I have done a number of prints with PVA as support material. So far i have no problems with carbonization or other: the material i have is really easy to print, at 195 or 200 degrees. it started steaming when printing at 210°, so i lowered. One hint hough: while PVA is water solubile, that does not mean you rinse it and it's gone. In my experience, it is mostly suitable for structures where you can reach the support material. I have tried a piece with small holes (approx. 1 mm in diameter) that i filled with pva and hoped to dissolve. After 12 hours submerged in water, most of the material was still there. It might be removable wherever you can reach with a brush or something similar, to remove the parts that have gone soft, so the still hard parts can be reached by the water. It might be possible to get better results if you can keep the water in motion, and preferably warm, since both seem to help dissolving the PVA. I remember from the old times at school, we had little heaters in the chemistry lab, that would spin a magnet when it was dropped in the solution. Something like this would probably be the best way. When you use it to support easily reachable parts though, it works like a charm. it sticks to the PLA jsut enough to be printable, but can be removed almost without any water. So, my conclusion so far: PVA is a good thing, and quite suited for printing with a (dual extruder) Ultimaker 1.

Since i have now done some tests with printing on glass, too, i would like to share my experience. I am using some very cheap 2 mm glass from the DIY store that i cut to size. I need to replace that with thicker material, though, because 2mm glass still bends far too easily. I fix the glass with paper clips to the original acrylic build platform of my UM1. I don't have a heated bed yet (waiting for the kit :smile: ). I have thinned standard wood glue with lots of water (like, 5:1 or something, untli it looks like milk) To get a perfectly flat surface, you can just pour this over the glass. You also see immediately where the glass was not cleaned properly, becuase there the glue won^t stay. You can also use a soft paint brush to spread the material. After it has dried (which takes maybe 3-5 minutes) you get a dull surface. Printing on the cold glass works very nice for me. So far i have only tested a smaller part (a cog wheel with 35 mm diameter). It stuck to the glass perfectly, and after removal and cleaning with warm water the underside was mirror perfect. I am currently doing a test print of a 200x80 mm object to see if the warping is better or worse than with the blue tape.

Which post do you mean, 3dcase?

I'd like to share my experience with the dual extruder kit, too. First of all: Ultimaker team, and Daid especially, you did a very nice piece of work there. Thank you! In detail: Assembly worked fine, i had no issues there. Calibrating took quite some time, as expected, but i managed to do that, too. So today i wanted to try my first print with PVA as support material. Printing the PVA works nicely, with no problems. After it started steaming a bit at 210° i lowered the temperature of nozzle 2 to 200, with beautiful results. Now i wanted to test the cura feature to use the second extruder for support material. In the expert settings i set the fill amount to 30, the distance X/Y to .1, and the distance Z to 0, since i would like to have the support material actually touch the printed object. I also set the support type to "everywhere", and the support dual extruder to second extruder. The print as such works well. Although i guess i still need some playing around with the PVA. However, i noticed some strange behaviour. First of all, i cannot find a difference in the tool path view betreen the two settings "tocuhing build plate" and "everywhere". In fact it seems that the "everywhere" setting does not work and instead the "touching build plate" setting is always used. Plus, cura does not create support for the vertical loop, although in my opinion it should, even in support type "touching build plate". So, all said, the dual extrusion kit is really cool, and it works fine with PVA support material, but in order to get the support material to be everywhere you want it, it seems to be necessary to create a second object for the support material and merge them. That is the next thing i will test. Hope that is of any help for anyone. Wish you happy holidays! (find below a screenshot from Cura. It looks the same both for "everywhere" and "touching build plate")

Thank you, JonnyBischof! I will look into that tonight.

Hello Daid / UM-Team, yesterday i finally upgraded to the latest Cura (so far i had used 12.12). I like it a lot especially the slicing speed is absolutely wow! Nice work! one thing, though: would it be possible to offer the skirt option from the older versions? I was printing some cog wheels (which came out beautifully by the way), but cleaning the brim is one heck of work. Switching off the brim doesn't seem to be a valid option, since i seem to need the "priming" of the nozzle. Would that be possible, maybe as an option in the "platform adhesion" setting?

Soweit ich das beurteilen kann, ist auch die Druckgeschwindigkeit ein Thema, besonders bei den Bohrungen (Ich drucke auch vor allem technische Teile und kenne das Problem) Da der Drucker ja eine "Wurst" aus Filament auf das Modell legt, könnte ich mir vorstellen, dass er die bei den Bohrungen ein wenig nach innen zieht, und zwar mehr, wenn man schneller druckt. Ich hatte jedenfalls schönere (und etwas grössere) Bohrungen bekommen, als ich die Geschwindigkeit deutlich runter gesetzt habe. Vielleicht hilft Dir das?

Alain, zur Frage ABS oder PLA: der Ultimaker druckt hervorragend mit PLA (sobald man ihn sauber eingestellt hat). Um mit ABS zu drucken, solltest Du entweder ein beheiztes Druckbett oder einen beheizten Bauraum oder beides haben, da sich ABS beim abkühlen recht stark zusammenzieht. Grössere Bauteile lassen sich mit dem unveränderten Ultimaker nicht in ABS drucken. Zur Festigkeit: Ich habe meinen Drucker, um eine Roboterhand zu bauen. Die Festigkeit und Masshaltigkeit von PLA war bisher ausreichend. Wenn Du eine sehr hohe Festigkeit brauchsdt, ist eventuell Nylon ein Material, das Du Dir anschauen solltest, aber auch das lässt sich nur mit beheiztem Druckbett oder -Bauraum sinnvoll verarbeiten. Die Oberflächen kann man übrigens auch verschleifen, oder je nach Material mit geeigneten Chemikalien glätten (also anlösen).

I recently bought rather cheap filament from a new source (because living in switzerland, i wanted to avoid the hassle with customs). I started having rather similar problems: one print works fairly smooth. then the second, or the third, if it was smaller prints, start underextruding and jamming. Removing the filament, cutting off the lump, reinserting, heating to 250° and pushing by hand results in first very bad flow, then eventually charred bits in the extruded filament, and sooner or later (later, for the most part...) i get clean material. Actually to me it seems the material is grainy or something. Since i use hite filament a lot the charred bits show up clearly. I found that the filament diameter needs to be measured rather exactly for longer prints, since, obviously, any measuring faults add up over time. And this cheaper filament is very unforgiving. I also started to retract the filament ratehr far (way out of the hot end, to be on the safe side, after each longer print. Maybe you have similar issues?

nach meinen (beschränkten) Erfahrungen sollte auf jeden Fall der Filamentdurchmesser so genau wie möglich angegeben werden. Da ich bisher noch kein völlig rundes Filament geshen habe, hilft m.E. nur: an vielen Stellen messen, und den Mittelwert nehmen. Bei der Grundfläche ist es m.E. so, dass hier vor allem mal das Bett sauber nivelliert sein muss. Ist die Düse zu dicht am Bett (Kontakt), dann ist der Widerstand natürlich viel höher. Der Kunststoff soll zwar angedrückt werden, aber er muss auch noch aus der Düse rauskommen. Und ja: Die Temperatur ist ein Thema. Je nach Material (bzw. Herkunft) brauche ich deutlich unterschiedliche Temperaturen. Wenn die Düse aufgeheizt ist, mit genug Abstand, drehe mal das Extruderrad von hand, und schau, wie das Material aus der Düse kommt. Ist es sehr zäh bis krümelig, ist (wahrscheinlich) die Temperatur zu niedrig (oder die Düse voller Krümel) Meiner Meinung nach sollte das Filament ziemlich weich aus der Düse kommen, in eiinem gleichmässigen Strang, und wenn man ein bisschen kräftiger Material nachschiebt sollte es auch recht schnell vorne wieder rauskommen. Wenn es Blasen wirft, ist es aber zu heiss.

After about 1 kg of PLA i had my first blocked hotend. It seems my blockage came from a print that aborted (yes i print via USB) so i had no extrusion but lots of heat (220°) over quite some time. Apparently the heat slowly spread upward until it caused the filament to go soft enoug to form a lump above the hotend, where the heat from the hotend could no longer really reach it to make it soft enough to be pushed down. For me, just removing the filament, cutting off the fat lump and reinserting it, then heating up and manually turning the extruder wheel to "flush" the hotend worked for me.