gael

Ici : http://www.factorydirect.fr/tube-air-comprime-calibre-en-ptfe-diam-4-6-couronne-25m-blanc-279.php Mais il doit y avoir aussi d'autres fournisseurs... ++ Gaël

Le seul problème que pose la modif avec le tube plus large, c'est de le tenir bien en place contre le bord du tube de laiton de la section chauffante. Comme le diamètre extérieur est similaire et l'intérieur plus grand, le tube est plus "mou" et le clip en plastique pas suffisant. J'ai imprimé le clamp de Owen http://www.thingiverse.com/thing:11864 pour assurer le maintien. Sinon, comme il y a un petit dégagement sur l’extérieur du tube de laiton, le tube de 4mm s'ajuste nickel. C'est d'ailleurs pour ajuster un peu mieux le tube en téflon sur le tube en laiton qu'on te recommande de le creuser un peu au foret de 4.5mm dans la page "jamming". La tête modifiée ressemble à ca: Par ailleurs, pour être plus tolérant du diamètre du filament et pouvoir me fournir ou je veux, j'ai refait le dispositif d'entrainement du fil en me basant sur celui de Geo Hagen: http://www.thingiverse.com/thing:15897 ++ Gaël

Hi Polymorph, I posted a picture of the filamanet extracted from the machine on the first page of this topic. You can see a restriction in the diameter of the filament just above the section that expanded in diameter. When this happens, it's very hard to remove the filament as the expanded section does not pass through the section of the tube strangled by the clamp. I managed to get out of this blockage by pushing hard on the filament during several minutes to soften the plug and pull it very quickly to pass the clamp before in hardens again... ++ Gaël

Salut! J'ai mis en route un topic exactement sur ce problème. J'en suis arrivé à la même analyse que toi. J'ai changé le tube pour un tube avec un diamètre interne de 4mm au lieu des 3.2mm du tube d'origine. Maintenant, meme avec le "pousseur de fil" qui fait des indentations sur le fil, l'alim de la tête se fait sans encombre. Avant je devais charger le fil en le poussant avec force à la pince. Maintenant, je le rentre en le tenant du bout des doigts... J'ai pu constater en plus que la pression énorme appliquée au fil faisait "gonfler" le fil ramolli par la proximité de la section chauffante. Or, un fil de 3.0mm avec une indentation qui lui fait prendre 0.2mm dans un axe et qui avance dans un tube de 3.2mm, ça fini toujours par coincer. J'ai pu sortir le fil d'un coup pour constater le phénomène: Ci après, une photo du tube de remplacement à coté du tube d'origine: Pas mal de personnes n'ont pas le problème si ils utilisent un fil plus fin. Avant de changer le tube, j'ai temporairement réduit le problème avec une bobine de chez Ultimaker qui fait 2.75mm de diamètre. ++ Gaël

Hello all, I used a length of 65cm for the upgrade. It's a bit longer than the original. edit : sorry, I meant 65cm... ++ Gaël

Hi! The metric one looks identical to the one I used. The other one looks good to me regarding the inner diameter. I would just check that the outer diameter is compatible with the feeder's quick-fit coupling. ++ Gaël

Hi Alaris, The Cura's retraction function gives very good results. Since I replaced the bowden tube with a tube with ann inner diameter of 4.0mm instead of 3.2mm, it's even better than before! ++ Gaël

Hello, I also have indentations on the filament: They look like this: I use a filament "pusher" derived from the Geo Hagen's one. http://www.thingiverse.com/thing:15897 It uses a knurled wheel from Fabberworld that works fine. I never observed an ovalized filament, even by thightening it a lot. ++ Gael

Hi! You got the same kind of problem as I had. You have a lot of friction in the tube, so you tighten more the feeder, so you get more indentation to the filament, so you get even more friction... Have you measured the diameter of your filament? It seems that this problem is less noticeable with smaller filaments. To solve the problem, I used this tubing: http://www.factorydirect.fr/tube-air-comprime-calibre-en-ptfe-diam-4-6-couronne-25m-blanc-279.php It allows a smooth extrusion with indented 3.0mm filament. Yesterday I noticed that Cura's retraction function that prevents stringing (by inverting feeder's rotation) works much better since the filament can move freely inside the tube. ++ Gaël

Hello all, I tried acetone before to switch to Dichloromethane. Acetone softens very efficiently PLA. It helps a lot to clean parts (nozzle...) but you still have to scrub it to remove the plastic. Dichloromethane completely dissolves the plastic. It's Acetone is handy to find and requires less handling precautions.... ++ Gaël

Hi! Your symptoms look at lot like mines (until I replace the tube). the tube is a remaining from a machine assembled by a friend. It's PTFE and 4mm inner diam / 6mm outer diameter. ++ Gael

Hi Joergen, I understand what you say. In this case, why does the extrusion stops even if the bowden tube is correctly held against the brass tube and the bowden tube does not move at all? (I placed marks on the original tube and when the filament got stuck, the tube remained in place.) ++ Gael

Robert, I agree with you, the worse case is the bowden tube being pushed back and molten plastic making a plug against the Peek part. What I stated earlier is that before to reach this point, if the pressure in the bowden tube raises too much, the extrusion will stall before the tube moves. A solution to improve that is to reduce the friction that has a role in the pressure in the extrusion head and at the same time reduce the back pressure by trimming the UM's Table. ++ Gaël

Hi Robert, What do you mean by "plastic getting in contact with the PEEK"? It seems to me that if the bowden tube is corrrecly held in place, the molten plastic never touch the peek; even with the pressure getting up. ++ Gael

Hi (again) I added the following post on this topic : viewtopic.php?f=21&t=932&p=5451#p5451 It's related to excessive pressure on the filament and back pressure leading to failed prints: From what I observed, when you print large areas completeley filed, the output of the filament is restricted by the short distance between the nozzle and the printed flat surface. A back-pressure grows in the heated section of the printing head that makes the filament bulge just above the heated section. The resulting friction of the filament against the inside of the bowden tube slows down the extrusion that may stall and make fail the print... You can first reduce this back pressure by leveling perfectly the machines table. This way you'll prevent the nozzle to get too close from the support that leads to a excessive back-pressure. Using a thinner filament (<2.9mm) also helps to push back the moment the extrusion will get stuck. You can do something to diagnose the problem: When you see the extrusion stalling, let the machine run and manually pull the filament out. you will be able to see the section of filament that bulged a blocked the extrusion. On this image, you can see the indentations that increase the friction in the bowden tube, the restriction in diameter from the horseshoe clamp that increase also the friction and the bulge of the filament just above the metling section that also inceases the friction on the filament. All this causing the printing to fail...

Hi! It's the same problem I had and that led to the topic : viewtopic.php?f=7&t=902 From what I observed, when you print large areas completeley filed, the output of the filament is restricted by the short distance between the nozzle and the printed flat surface. A back-pressure grows in the heated section of the printing head that makes the filament bulge just above the heated section. The resulting friction of the filament against the inside of the bowden tube slows down the extrusion that may stall and make fail the print... You can first reduce this back pressure by leveling perfectly the machines table. This way you'll prevent the nozzle to get too close from the support that leads to a excessive back-pressure. Using a thinner filament (<2.9mm) also helps to push back the moment the extrusion will get stuck. You can do something to diagnose the problem: When you see the extrusion stalling, let the machine run and manually pull the filament out. you will be able to see the section of filament that bulged a blocked the extrusion. On this image, you can see the indentations that increase the friction in the bowden tube, the restriction in diameter from the horseshoe clamp that increase also the friction and the bulge of the filament just above the metling section that also inceases the friction on the filament. All this causing the printing to fail...

Hi, I use Dichloromethane to clean cold PLA. It's very efficient. A cold nozzle with PLA inside gets clean as new after an overnight bath in this solvent. I use this solvant to glue plastic parts together. I can be found at technical plastics suppliers or in places selling chemical products. ++ Gael

Hello all, I replaced the original bowden tube with a new one. The inner diameter is bigger (4.0mm instead of 3.2mm). Then a filament indented by the knurled bolt doesn't produce a big friction in the tube. Before, I had to force a lot on the filament to load in on the machine. Now I just have to lightly push with the filament between the thumb and the index. https://picasaweb.google.com/1128421795 ... May272012# Another problem with the original tube is the horseshoe clamp. it strangles a bit the tube to hold it and then its inner diameter is reduced by a few tenth of millimeter. This increases a lot the pressure required to extrude the filament. this high pressure and the proximity of the horseshoe clamp with the heating section of the print head makes the filament expand between the horseshoe clamp and the printhead that makes the jamming. With the new tube, a small reduction of the inner diameter does not block the filament anymore. Or at least the friction became very reasonable. As the tube is thinner, it was necessary to add to the UM Owen's tube clamp to prevent it to move. Now it seems to work fine and I can print with the indented 3.0mm filament...

Hi. I just found a piece of PTFE tubing. outer diameter is 6mm and Inner is 4mm. It tested it up to 300°C with a soldering iron. It seems to withstand the temp. I made a test by hand with my 3.0mm indented filament and the force required to push is through is very low. I have to find out how to reliably hold it in place on my UM. I think I'll print Owen's Bowden clamp for that... ++ Gaël

Hi Daid, I bought my filament from Paoparts. I have 4 rolls of 1.5kg (one red, one transparent, one blue and one white) I only unpacked the white one.... But I also though is might be interesting to design a "filament calibrator" to adjust filament diameter and circularity to optimal values... I'll have a look at the "trekijzer"... Thanks for the tip! ++ Gaël

Hello all, I measured my filament and its diameter is 3.0mm. In theory, it should be ok if I believe what is written about filament tolerance on the Ultimaker's consumables shop. (2.8-3.1mm) When I say that the head gets blocked, I mean that even when pushing very hard the filament using a plier, I don't get anything coming out of the nozzle. I disassembled several times the head, cleaned any trace of PLA with solvent and put everything back together with the small improvements mentionned in the "jamming" page. I switched back to a silver filament bought from Ultimaker (2.75mm diameter) and the friction in the bowden became very reasonable and the head did not get blocked during several hours of printing. So you were right, my filament was too big. I think that the horseshoe holder reduces locally the inner diameter of the bowden tube just enough so that a 3mm filament with a bit of indentation from the knurled driver gets stuck there. This added to the high level of friction in the bowden prevents any extrusion... I will have to dispose of my spools of 3mm PLA filament and gets some 2.75mm filament from Ultimaker.... Thanks for your advice!!!

Hi Daid, I will check that this evening.... Anyhow, does everybody accept that a few tens of mm variability in the filament diameter or circularity can jam the machine? Gaël

Hello all, I am in trouble with my machine. My problem is the following. The friction in the bowden tube is very high. Then the extruder motor has difficulties to push the filament. Then, most of the availlable torque is wasted in friction instead of creating the pressure to extrude properly. pushing the filament by hand down to the head is very difficult.... As the friction is very high, I have to tighten a lot the filament to keep it moving in the bowden which adds small indentations to the filament that increases even more the friction. (I had to upgrade the extruder into a Geo Hagen style extruder to get enough grip) Aside from that, The printing head gets stuck all the time altough I never can see any PLA plug when I dissasemble it... I start to be a bit desesperate on this last point.... Any idea or advice? Gaël

Hi Daid, Thanks for the quick answer. As I am just discovering Cura, I haven't looked yet at printrun... For the extruder problems, I'll see if it comes from "bowden creeping"... My actual hypothesis is more about the traces left by my new filament extruder that increase the filament diameter and it blocks somewhere at the entrance of the printing head (juste before it melts). Best regards, Gaël

Hello all, I installed Cura RC3 (first time with Cura), and it works fine. At a first glance it seems much better than ReplicatorG! As I struggle with my extrusion problems (printing head jamming all the time) I lack a feature of ReplicatorG : The possibility to actuate the extrusion motor "manually" from the software (set a speed and motor direction). Is this available somewhere in Cura? If not, is it something that can be added in a fututre release? (Middle term / ideal solution) In the mean time How can I use (alternatively) Cura and ReplicatorG without having to reload each time the Ultimaker's Firmware? Then I'll be able to use Cura for slicing/printing and use ReplicatorG for troubleshooting my extrusion problems. Gaël