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Everything posted by abstract

  1. UDPATE: In case anyone arrives here, I found the solution: https://ultimaker.com/en/community/18342-successful-result-octopi-start-and-end-gcode-for-um2
  2. Hi Folks. I have been using UM2 for nearly 2 years and for most of that time I used Octopi to control the UM2 remotely. After a recent Cura / Firmware update the Octopi seemed to be failing to print properly and today I got around to fixing that. I got the latest Octopi image and then I started messing around with the Start and End GCode in Cura. Since I sometimes use Octopi and sometimes print with SD card from the front of the UM2, I wanted to make sure that using these 2 modes were compatible. In particular, the 'extrude after print' and 'prime before print' needs to match up reasonably well when switching between the 2 different control modes. Also, I like the way the UM2 primes material on top of the front right metal clip, and I wanted Octopi to do the same. Pouring over forums, I didn't find a definitive answer so I did a lot of trial and error, and here are the results I have finalised. Of course, to clarify- In Cura you need to have 2 machines setup, one for UM2 native using UltiGCode and another one using REPRAP (although maybe with this extra start / end stuff, Octopi might work with standard UltiGCode??) - anyway assume you need RepRap (Marlin/Sprinter) mode in your second Machine "UM2 via Octopi". Now, put in the following in the Start and End GCode sections in Cura: START CODE: G21 ;metric valuesG90 ;absolute positioningM82 ;set extruder to absolute modeM107 ;start with the fan offG28 ; home all axesG1 F12000 X5 Y10M109 S{print_temperature} ;Uncomment to add your own temperature lineG1 Z30 ; lowerG92 E0 ; zero the extruded lengthG1 F100 E40; purge nozzle with 50mm of filamentG1 X80 Y60 F3000 ; move aside of the puddle of primed plasticG92 E0 ; zero the extruded length againG1 F{travel_speed}M117 Printing... END CODE: M104 S0 ;extruder heater offM140 S0 ;heated bed heater off (if you have it)G91 ;relative positioningG1 E-1 F300 ;retract the filament a bit before lifting the nozzle, to release some of the pressureG1 Z+0.5 E-15 F100 ;move Z up a bit and retract filament even moreG28 X0 Y0 ;move X/Y to min endstops, so the head is out of the wayG28 Z0 ;platform downM84 ;steppers offG90 ;absolute positioning I tested combinations of starting with a UM2 SD card print, then Octopi and the other way around, and whilst the retraction / extrusion at the end and start of prints aren't exactly the same, they do seem to be compatible with enough primed in both modes to start the print with a clear run of filament. The Octopi now moves the head to the front left (after the bed heats up) and starts heating the head in that position so it drips down to the front left. Then when its hot, it primes (quite a lot) and gets you started with a decent flow. I am using Cura and UM2 Firmware version 15.04.2 Hope this helps someone else doing the same thing. Mark
  3. I have got the same problem. I have had to give up printing via OctoPrint for now. I presume this must be the updated firmware in the UM2 ? I was very happy with Octoprint until I recently updated the UM2 and Cura
  4. Hi Folks. I have just tried using ColorFabb XT White. Total Fail. I have had a reel here since March, waiting to upgrade my UM2 with Stainless Steel nozzle. Finally today I installed my Olsson Block, with 0.4mm Stainless Steel nozzle, for the XT. Tried the 10mm3 cylinder test with XT. First test taught me that I can't print XT onto clean hot glass - it left the bed within a few cycles. So I used glue stick. This time it stuck OK, but even at 3mm/s I got a feeder skip and immediately the print was over. Unlike PLA where under extrusion will droop or wrap but still basically stick - I found the XT stopped sticking to the print and started flailing in mid-air or sticking to the nozzle. I was printing with ColorFabbs recommended settings - 240c / 70c. Standard 10mm3 Cylinder test. With PLA and the Brass 0.4mm nozzle this machine did 10mm3 pretty nicely, before and after the XT test. I have happily printed thousands of hours of PLA on hot clean glass, but this XT stuff just seems like too much trouble to bother with. So, what am I doing wrong, or is this material just impractical ?
  5. Confirmed - UM2 GCode from new Cura is no good for Octopi. First test failed because the bed didn't even raise. Anyone have any info on getting REPRAP format GCode out of new Cura, for use with Octoprint and a UM2 ? I am also trying to update with the latest Cura - I use Octopi to deliver the prints to the UM2 which is operated remotely. Previously we had to use the REPRAP export GCode format - but I don't see an equivalent in the Cura Prefs for the machines. With respect to heat-up, I always manually heat the bed to 75c, then manually heat the head to 230c, and whilst watching the camera feed on the Octopi, I push extrude 2 or 3 times and watch the filament come out into a ball. I also hit the home head a few times and this eventually makes the ball of filament fall to the ground. Just as it does that I start the print. This ensures a fully primed head and gives great results on the first layer. Maybe the standard UM2 GCode output from Cura will give the sam results as the REPRAP mode previously used, although I seem to recall that the UM2 output does NOT include the temperature ? since it is set by the filament selection in the UM2. Having said that I see that the Cura version does allow selection of temperature - so maybe that overrides the setting in the UM2 ? Anyone have any answers here ? Thanks. !
  6. I am also trying to update with the latest Cura - I use Octopi to deliver the prints to the UM2 which is operated remotely. Previously we had to use the REPRAP export GCode format - but I don't see an equivalent in the Cura Prefs for the machines. With respect to heat-up, I always manually heat the bed to 75c, then manually heat the head to 230c, and whilst watching the camera feed on the Octopi, I push extrude 2 or 3 times and watch the filament come out into a ball. I also hit the home head a few times and this eventually makes the ball of filament fall to the ground. Just as it does that I start the print. This ensures a fully primed head and gives great results on the first layer. Maybe the standard UM2 GCode output from Cura will give the sam results as the REPRAP mode previously used, although I seem to recall that the UM2 output does NOT include the temperature ? since it is set by the filament selection in the UM2. Having said that I see that the Cura version does allow selection of temperature - so maybe that overrides the setting in the UM2 ? Anyone have any answers here ? Thanks. !
  7. BEFORE AND AFTER MAINTENANCE, 30 Minutes from zero to hero. Read about it here: http://umforum.ultimaker.com/index.php?/topic/8467-serious-underextrusion/?p=80124
  8. Hi There. So - here is a great example of what some careful maintenance can achieve. Witness the photo below which shows a 'before' and 'after' maintenance on the SAME printer, about 30 minutes apart. Here is the story: - I have had this Ultimaker 2 since November 2013. It was not until May 2014 that I started evaluating its performance - since until then I was quite happy with 0.1mm layers at 50mm/sec speed - and most Ultimakers can do that *fairly* well - even sick ones. Anyway - as soon as I first did the 10mm3 test - I could see I had a problem. To cut a long story short (long story is at http://umforum.ultimaker.com/index.php?/topic/4586-can-your-um2-printer-achieve-10mm3s-test-it-here/) I fixed this problem once before, with *alot* of work and research. The good news is that that knowledge is now pretty well known, so today when I blew the dust off my UM2 after several months, I was prepared. Over the summer I really hammered the UM2, printing a batch of 200 prints of the same thing, each took about an hour. As the batch progressed, the quality deteriorated a little, so it was clear something was 'wearing out'. At the end of the batch I shut down my little factory and got on with something else. Today I came back to the UM2, just as I had left it (in my garage), and the first thing I did was run a 10mm3 test. That is the green one on the left of the picture. As you can see - its a total fail. Fortunately, I knew what to do - and here it is: 1) My printer has been stored in a (cold) garage (in the UK). Its not really damp as such, but its what you might expect. I had left the filament loaded and on the spool on the back. So, we can probably expect the filament to be a little damp. 2) I brought everything inside for a bit of TLC. 3) First task, take the old filament out. As it happens, I ended up with the filament getting jammed in the bowden tube on the way out - due to an oversized blob at the nozzle end. I removed the 2 bowden clips and got the tube out, with the filament still stuck inside. After a bit of work with pliers I got the filament out. Now - important - I took this opportunity to lubricate the bowden a little - I got a length of filament and sprayed it with silicon lubricant spray - then worked it back and forth inside the bowden tube for a while. You will feel the (noticeable) difference this make. 4) Next, I did the hot-in-cool-out process, (some people call it 'atomic' I believe). Basically, with the bowden removed and filament manually fed into the top of the heater block assembly, heat up the head to 190 degrees (or a little hotter) and push the filament through until you get plenty coming out. Now let the nozzle cool to 90 degrees, and as soon as it does, pull the filament up and out on one quick jolt. You will get a nice little rocket shaped tip to the filament. If you study this tip you can learn alot about the state of your head. For example, if its covered in old filament, you may want to repeat the process a time or 2 more, to clean out all that old stuff. Also, look at the *shape* of the rocket - this is a cast of the inside of your head block. A perfect cast would have the 3mm filament join seamlessly to a 3mm diameter rocket with perfect smooth sides and a smooth taper to the 0.4mm tip. What you might see instead is buldges, particularly at the junction of the filament and where the rocket starts (there are photos of this in the 'long' thread linked above). The buldges may indicate problems with the assembly, or the teflon coupler. You might have a stretch between the 2 pieces if you pulled hard, so ignore that. 5) In my case I was pretty certain the teflon coupler was worn out, from previous experience, so I disassembled the head block and took out the white teflon coupler. As I expected, looking inside the hot end of the coupler there was buckling inside with a small cavity in the walls before the filament exits the coupler. I believe that the filament gets jammed on this, both when loading filament (thats a good sign of this problem) and also whenever snags in the filament go through (particularly when the feed motor has chewed the filament a little). I had a spare Teflon piece in stock so I quickly replaced it. 6) Having meticulously reseated the bowden tube (make sure there is no gap between Bowden, teflon and nozzle sections of the filament path), I put on some nice, new, dry Faberdashery PLA, from loose wrap of material. 7) See the after picture. This was literally the next print. You can see that the results go from zero to 10mm3. If i had time, I would have also dismantled the feeder mechanism and cleaned out all the little PLA chips which build up in there. Summary: - Get a spare Teflon Coupler or 2. I believe this is the #1 fix for under extrusion. - Lubricate the Bowden tube - Clean out the nozzle with the hot in- warm out method - Use dry Filament, on a loose spool. I will also run a little sewing machine oil into the rails, since this UM2 had such a hard run, and probably grease the Z axis. However these things wont really help extrusion, but may keep it running quiet and accurate. Finally - I believe Ultimaker have now created a glass-impregnated Teflon coupler, (Mine are all the original type) and I suspect the glass might help keep them going longer, since overheating and general heat-fatigue seems to be what makes them deform. I hope this helps. Cheers
  9. So.... I have now completed 70 prints (140 half parts).... So far so good. The Faberdashery PLA is working out very nice at 0.2mm/75mm/sec. This is about 120 solid hours of printing. However. I have started to hear the UM2 groaning a bit when the head moves across. I have a feeling it wants oil. So far I have done no lubrication. Grease on the Z screw, I am happy with - and I have the UM supplied stuff. I am still trying to get hold of some sewing machine oil, but I was not really sure what to lubricate - I read somewhere that the X/Y is 'self lubricating' - is that true ? Do I actually put oil on length of the metal rods ? I presume the bearings into the frame dont need oil ?? Could you explain precisely what "Smooth Axis" and "Cross Rods" actually means ? Thanks Mark
  10. A bit more information for the mix. As you may have read a dozen pages or so ago, I went through a long testing process to find out why I had under-extrusion problems and alot was learned. In my case the biggest problem was a melt-distorted teflon coupler, but it also became clear there were alot of other smaller things which contributed. Anyway - after replacing the teflon coupler, I was finally able to start printing at 0.2mm and increasing speed a little. Having printed for 6 months at 0.1/50mm/s I was actually very pleased with the results at 0.2mm/50mmsec - particularly for engineering parts. For the last 2 weeks I have been engaged in 'mass production' of a piece to be used in an Artwork - the artist wants 150 of the same thing, and each print is nearly 90 minutes. The benefit of mass production, is that you really get to see the consistency of different changes. A bit like printing this crazy cylinder over and over (you remember doing that ??? !). So, after a few tests, and with an acceptance of some quality drop, I chose to print at 0.2mm and 75mm/sec - for the most part this gives pretty good results. Also I found another great tip - my print is basically a big antique doorkey, and the prints are done in 2 halfs, split down the center of the shaft. This allows you to print both as semi-cylinders then glue them together for a perfect (ish) print, with no support. I soon realised that the Ultimaker 2 was spending quite a bit of time laying down base layers for the 2 sides, which I was about to stick together and no-one would ever see. Eventually I discovered a checkbox in the expert options of Cura which allows you to skip the base layer. Now my prints go right into 20% fill from the first layer, saving about 10 minutes printing those filled layers. There is another benefit too - previously I had been superglueing the crisp flat bases together to make the cylinder from 2 halves. This was a tricky business with little room for error and issues like superglue ooze and that white vapour mess. Anyway - having skipped the flat base layers, I am now very happily using a glue gun, and the honeycomb 20% fill is the perfect base to apply quite alot of glue on one side, then gently mate it with the other - with the option to shift the positioning for a few seconds to make it perfect. I am really delighted with the results, and the glue gun material has plenty to cling onto inside the 20% fill matrix. Finally - to the latest lesson. With this mass-production build I am getting through quite alot of Filament (all PLA). I started off with 2 reels of Ultimaker Black PLA, and this went reasonably well. One reel started to get 'tangled' as it got to the last 30%, and this did cause a few under-extrusion jams. I ended up spooling it off that reel and onto another reel by hand, and following this, the reel continued without any clogs. So, where to buy more Filament in the UK. Well - my UM2 has a custom made home in my quite full garage, in a little alcove with a sliding platform so I can slide the UM2 forward to get to the filament. I dont have the space for a floor mounted giant spool - so I am sticking with the regular reel on the back, and 2 filament guides. The only reel-based PLA I could find easily in the UK came from 3DFilaPrint. The buying experience was very good, and a reel of black 3mm PLA was promptly delivered at very reasonable cost. However.... as soon as I opened the box I could see that the PLA (from "RepRapper") - was not the same grade as I had been using - the Filament surface is very matt, and textured, and the material is slightly 'biscuity' - like the density is lower ??? It measures out at around 3mm even, which was a bit of a worry given all the clogs I have suffered. Anyway - I gave it a try - initially I was a little surprised to see the material looking slightly 'pale' as it came out, a bit grey / charcoal rather than deep black. The print started OK, but after about 10 minutes the whole system was totally jammed up and the rest of the print was ruined. Clearly either the rough texture or the diameter of this material is not going to fly reliably in my UM2. Also, as I removed the sad looking print from the glass I realised that the actual printed filament was not the same as previous PLA prints - rather than a rigid print, this one was rather floppy - so again I think the density/content of the material probably translates into the print. Very sorry 3DFilaPrint - great service - but this Rep-Rapper material (for me) is scrap. Fortunately, I had also placed an order with Faberdashery. I have used their white PLA before and had great results, but being a space-limited 'reel' person, I have a big problem with the loose PLA idea (even though I know this can contribute to avoiding underextrusion). Anyway - I took 100m of Black Faberdashery PLA and wound half of it onto a reel (that took about 20 minutes...). This is now medium loosely wound. The next print could not have been more different - crisp, black, and consistent - nothing like the rep-rapper aborted print, and actually quite alot better than the Ultimaker PLA prints (of which I had already done about 50). Faberdashery filament measures 2.85mm which is also great. So, to summarise - all PLA is not equal. In my experience: Ultimaker PLA : Pretty Good, but hard to buy in the UK Faberdashery PLA : Excellent, easy to buy in the UK but not on a reel RepRapper PLA (from 3D FilaPrint) : Easy to buy in the UK, but Unusable ColorFab PLA/PHA mix : Had some extrusion problems with this, although it was some time ago. The 2 symptoms of bad PLA, are tendency to under-extrude (because of diameter related jams, possibly surface friction, and poorly wound-on reels) and quality of finished prints - whether crisp and rigid or 'stale bread - bendy' As I have said repeatedly - this whole extrusion path is a symbiotic system - all the parts need to be right to make it reliable - most often its not a single problem causing under-extrusion, so there is no single 'quick-fix' Cheers Mark
  11. Thanks for the tips. Incidentally I think I may have a loose rod - its clunking alot more than it did when it was new and I have a feeling there is some forward to backward play in one of the side rods. How do I fix that? Also, I noticed what may be a design-flaw, and lead to failures long term - the LED lighting cable is fouling one of the pulleys, and I am sure its going to eventually wear through it. I have posted a video here: http://www.gallery.co.uk/private/UM2-LED-Fouling.mov I will try to reglue the strip once this print is done, but I have noticed all along that the LED strip is trying to come off in various places. Cheers Mark
  12. Hi Folks. I am about to start a long run of prints (of the same thing) which will go on for several weeks. Maybe 100-200 2-hour prints. My UM2 is already 6 months old, and I have not done any maintenance on it (except replacing the Teflon coupler and the Bowden tube). I wonder if anyone can tell me the procedure for general maintenance on the UM2. What should I be servicing before I start the run ? Thanks Mark
  13. So... The new Teflon Piece arrived, and it made a big difference as you will have seen from my previous posts. Today I changed the material and took the time to perform a test of the 'hot push, cold pull' with the new teflon. You can see below the difference between the results from the old melted teflon and the new shiny teflon. The bulge at the neck on the melted teflon sample is where the filament was getting stuck and causing extrusion restrictions. Before Replacing Teflon - note the neck bulge : After replacing teflon - much cleaner
  14. Hey Folks. So an update from me. UM sent me some replacement parts, and I just fitted the new Teflon Piece, new Bowden Tube and new bowden tube clip on the print head end. I also printed a little pulley to help position the filament before it hits the feeder. First print, all defaults: Thats a result... no babysitting, no extra hot, no flow rate mods. 220 degrees right from the file, no tweaks. So... I think we can conclude that the issues I was having were related to 'snags' in the Teflon and perhaps the bowden. Also, I noticed that the old bowden tube was decidedly floppy at the print head, and I could see the internal dimension was larger that end compared to the feeder end (wear ??) the new bowden does seem to be more firmly fixed into the print head. However...... I still had a problem loading material, it stuck at some point inside or past the teflon piece and would not load. I tried straightening the filament, and loading again - but still stuck. So, I just homed the head, and used move material - this time it came out fine. The critical point here is the location of the head as we get material flowing. When in the material load position its front and centre, with the bowden tube quite 'stretched' out, and probably pulling and causing a bigger curve at the head end. When homed for move material - the head is back left, with much less pressure on the bowden tube. I believe this may be important, and perhaps the material loading head position should be further back. Also, I am hoping the filament will feed in OK at the start of each print, after its 20mm retraction after printing, I have also got a new nozzle, and the newer weaker spring for the feeder - I may add them next, but I think for the most part my major problem is much better. I suppose the question is whether this is going to be regular maintenance for UM2. Are we going to have to change the teflon piece every 4 or 5 months ? If so, I think UM need to make this a low cost sundry item easily available to order from their site (and perhaps at international local vendors). I didnt go as far as printing one of the alternate feeders, although I suspect they will add a little more. Ultimately, as I suspected, this whole issue is controlled by a symbiotic family of: 1) Control of angle of filament as it enters the feeder, plus - on the floor coming up is better than on a reel on the back. 2) Feeder tension, design etc. Make sure its not full of bits of torn up filament. Alt feeders may help a little. Feeder can cause filament dings when it skips and these get stuck further down the path. 3) Clean path into the feeder end of the bowden tube, otherwise feeder kicks will snag here. 4) Friction in the bowden (some people tried WD40 with improvements). If the feeder is chewing the filament, it may snag more everywhere, maybe less tension needed ? 5) Angle of Bowden tube into Print head - same as into the feeder, needs to be straighter, to help it as it hits the teflon etc 6) *Critical* - teflon part condition - age seems to create distortions which are prime points for filament snagging, especially when loading new material, and starting a print after the 20mm retract. 7) Temperature - for fast prints a bit more heat can help keep things moving, but this might end up compromising the teflon creating issues down the line. All these things need to work in harmony - so stop looking for the 'one fix' for this problem and embrace a holistic approach to the entire filament path. Thanks for everyone's support and comments. Next time I print for real, I might actually try going faster than the stock 50mm/sec 0.1mm layer....... Now my UM2 is going back into the garage, and my relationship with it will be thru Octoprint again. Cheers Mark
  15. Just a quick Update from me. I am still waiting on the replacement Teflon Piece etc from Ultimaker. I don't have any indication of when it will arrive. Meanwhile, I carry on printing with great care. Most of the problems caused by the distorted Teflon (apart from limiting speed) are problems loading filament (at least 50% of attempts the end gets stuck in the teflon and never hits the nozzle. Also I am having lots of problems now at the start of prints. There seems to be some issue related to earlier retraction and not getting enough filament to the head early on in the print. I will often get massive underextrusion for the first 30 seconds - this usually messes up the first layer so bad I have to abort. I think the retracted filament is getting snared up in the teflon piece's distorted ripples (see earlier post with photo). Since I brought the UM2 into my office for all this testing (from outside in the garage), I am using the front panel printing off SD. Ironically when I used to print remotely via Octoprint I always hit the 'extrude' button a couple of times right before starting to print, and waiting until I saw a blob form, then drop to the floor - so the nozzle was always perfectly primed when the print started. With the front panel method I don't have such an easy time. Anyway. Once I finally get the new teflon tube, I will do the test cylinder prints again, and hopefully we can draw some concrete scientific conclusion from this whole story. My feeling is that the new Teflon will help alot, and combined with a filament feeder, I might possibly make it to 8mm3 per sec... Here's hoping...
  16. I did print at 230, with 95% flow: For my tests, temperature was just one variable. Up to 240, it adds a percentage improvement, down to 210 its worse. The biggest improvement comes from manually feeding the filament into the feeder, and praying there is nothing going to get stuck in the rut in my Teflon. Switching from 100% to 95% flow feels like maybe it helped, but really I think the problem is NOT about over-pushing beyond what the nozzle can deliver and its more about achieving a clear, unobstructed path for the filament from the reel to the nozzle. I do also feel like my feeder is overly aggressive when it kicks, and I hope to put in the newer (weaker) spring. I also want to make it a gentler path along the tube and hot end somehow. So, my plans include: 1) Replace Teflon 2) WD40 in Bowden 3) Weaker Spring in Feeder (to reduce kick-damage and later problem with nicks) 4) Burn out the nozzle 5) Finish my design for a 'feeder - feeder' "Feeder-Feeder version 1.0" - needs further work: Not 100% certain it will help, but feels like it might. Meanwhile, I can print slowly and mostly it works OK. I am having problems loading filament and I am pretty sure the end is getting snagged in the Teflon. I plan to start sharpening the filament when loading. Cheers Mark
  17. I only tried once. With PLA and UM2 I print direct onto the hot glass (60-75c) and it sticks well. I only get warping with PLA with a large base print and thicker material around the edges (a thin print doesn't warp). I tried the same thing with ABS and it was a total fail. Layer 1 looked great but before long the whole print came off the glass. So, printing ABS onto clean glass does NOT work. I believe the answer is to coat the glass with an ABS/Acetone mix fluid, there are posts in the forums about it. 'Magic' Juice seems to be the correct approach, although I never tried it. PLA works well for me - the main attraction of ABS would be to make joining pieces together easier. Cheers Mark
  18. How do you think this will help ? I guess the only effect is to move the teflon away from the heat. However its creating a larger void into which stuff might snag ? Doesn't turning the coupler change the space between the coupler and the heating block ? The teflon seems to just sit inside the coupler, pushed in with the spring. Clarification ?
  19. OK, so when I had the head open I did fire a gas torch down the head for a while. Not quite exhaustive, but I wasn't ready to start disconnecting the temperature probe and heater. I did try pushing filament through the teflon. For the most part it works fine, and even with quite curved filament it goes through fairly smoothly - HOWEVER, there most definitely is a tendancy for snags (like the start of the filament) to hook into the rut in the far end of the teflon - so if there are any dings in the filament I would guess they will snag inside the teflon (but we dont know how hot it is down there so maybe its different during printing. The feeder tension has not been adjusted since new, the white marker is at the TOP - I guess this is minimum - its an early UM2 - spring seems *very* strong. Maybe I need the weaker spring ? Now to some more encouraging information: The next thing I started to look at is the feeder. I took it apart and found tonnes of plastic dust: Anyway - I cleaned all this out, and I also looked at the filament path going into the feeder. It looked like the plastic cutouts where the filament enters at the bottom were messy, so I filed them out Then, I put it back together and decided to try something different. Basically I really babysat the filament entering the bottom of the feeder. I held the filament so it had a clear path into the feeder, without pulling against the curve. I didnt really apply much pressure, so mostly I was easing the filament in, saving the feeder from the extra problem of the curve-pressure. Then I started a print - 240 degrees at 95% flow, with me babysitting. The result ! Amazing improvement: All the way up to 9 with only mild incidents. Interesting - this suggests that fundamentally the material CAN flow through my hot end (even if it might snag on dings in the filament). next I wanted to see how it worked at 240 / 95% if I didnt babysit the feed-in : So, pretty good still, barfed at 8mm. This is 240degrees, 95% flow, no babysitting (just making sure the filament was not stuck somewhere on the back- just very loosely spooled hungg on the holder, wide loops of faberdashery non-wound. Next, to answer your question, I tried the same thing at the default temperature for the cylinder, which appears to be 220 degrees. This is 220 degrees, 95% flow, no babysitting of feed in: barfed at 6mm. So. Let me summarise what I think we have learned. 1) The Teflon part gets distorted over time and can potentially cause dings in the filament to snag and create an extra load on the feeder 2) The nozzle can be blocked, and we suspect it may not give 0.4mm beads, so some alteration in the volume calculations is required. 3) The feeder may be contaminated with old debris. 4) Printing at 240 degrees definitely helped - perhaps its generally reducing the pressure, or maybe its moving the heat up the hot end and making the teflon hotter and more tolerant to dings in the filament. 5) Feed in to the feeder seems to be pretty important on my machine, and the filament inlet seemed to be a bit sharp. All those people saying put the filament on the floor are probably right - the pain of getting off the spool and into the feeder seems significant. The end of the roll gets more curved and this hurts the feed-in to the feeder as well as creating more pressure all the way down the bowden tube and in the teflon part. I think the overall message is that this filament path is a symbiotic system - all the pieces are playing a part and failure can be a combination of cause and effect across multiple parts. This may be why some people who replaced a single part did not solve the problem. For me - I am going to design a guide to do what I was doing with my hand in the photo above - to keep the filament straight into the feeder, probably around a large radius. I want to replace the teflon and nozzle. Maybe I will try one of the alternative feeder designs. I think I am approaching the end of this investigation. I will test again with the guide etc, and if I get new parts. Thanks to everyone for your comments and suggestions. I hope the information I have added to this thread will help those that follow. Cheers Mark
  20. Well, i didn't really see any way to clean up the deformed lip. I put a drill through the teflon piece, but the 'rut' in the teflon is a temporary *widening* of the shaft - so it could be a 'catch' point for unevenness in the filament - where the filament might have been carried along in the tube, with the kink riding along the inside of the bowden tube - then it gets to the rut in the teflon and it pops into the rut and stays there. So this print is after I reassembled the head, with some very minor clean up of the teflon. I think there is more going on. I would really like to replace the teflon. No answer as yet from the 2 emails sent to Marrit at UM requesting a replacement (under warranty or chargeable) Do I have the worst results of anyone on this thread ? Anyone failing earlier than 3mm cubed per sec ? Mark.
  21. OK, here is a print at 95% flow at 210 degrees. I used a fresh bit of filament which had not been retracted. My UM2 simply cannot feed fast enough to get past 3mm. First I see thin extrusion (does this mean blockage has started further up ???) Then I get feeder kicks, and then major under extrusion. So, to be clear - I do see under extrusion starting sometimes BEFORE the feeder kicks. Where to now ?? Mark.
  22. Normally about 10 degrees (outside) but for the last 3 tests and hot end investigation I have brought UM2 indoors where its 20 degrees Doesn't seem to have helped. Thanks Mark
  23. OK, so I am trying visualise the path of the filament through the hot end, to see where it might get snagged, apart from simply being constrained by the nozzle : I can see 2 places. First here is a breakdown of the parts: and here they are assembled: Some parts are HOT and some COLD and *maybe* some are 'WARM' ?? The heater block and nozzle are definitely HOT, and any material inside these bits will be molten, and presumably wont 'snag' I am not sure what the temperature state of the 'metal coupler' is. Since its screwed into the heater block I would guess its pretty hot - and the 3rd fan is doing its best to cool this. Judging by the heat damage to my teflon piece, I guess its not doing a perfect job and the teflon is also getting pretty hot. Now... how hot ? Hot enough to melt the filament ???? or just make it pliable ? Presumably if its pliable, it may also be losing its stiffness in the teflon / coupler stage, and this may mean that the mechanical movement of the filament behind it may NOT be full transferred into moving the filament in the Teflon / coupler stages. So, we are probably getting deformation of the filament here, and it might even be squeezing back from the nozzle up to fill any void in this area. Teflow is non stick and presumably this stops filament sticking and drying on the teflon. So, it would be nice to know the state of the filament as it passes through this sequence of pieces. I made a movie of the path through the hot end, and there are 2 places where we have potential 'voids' - they are the white rings in the movie below: The first white ring is where the Bowden tube sits inside the teflon piece. I presume this should be pushed as hard as possible to make this ring zero. I think the temperature here is cool, so no chance of melting and filling this void - BUT this is a 'catch' point for any dings in the filament - such as those in my red filament photo in an earlier post. So we could get some resistance here. However, lets think about the second white ring, which is the junction of the teflon and the heater block *inside* the metal coupler. This gap is HOT - presumably very hot. The teflon appears to be pushed in using the spring, I suppose to close up this gap - but I can't tell if it makes a flush fit (anyone know ??) - however, whenever we pull out filament from the hot-in cold-out cleaning method, I see a plastic ridge from about this point, which suggests there is a gap here. However, these ridges may also be from the rut just inside the bottom of my teflon piece. I would like to think that this gap between the pieces is hot enough that its NOT going to catch any filament dings. However the rut in the teflon probably is not so hot Here is a good example of the effect on the filament: So, anyway - there are my observations on the hot end. Analyse away - and let me know what you think I should do next to get myself printing more than 3 cubic mm/sec Mark
  24. OK. more info, 1) After the last test where the feeder had skipped at 4-5mm, I noticed nicks in the filament, inside the bowden tube. Its possible that these get more blocked when they hit irregularities inside the teflon tube (see below). So the Feeder *is* chewing up the filament a bit as it skips, and this might exacerbate the problem by creating more resistance when those nicks hit the teflon. Next - Hot End !! I dismantled the head, to take a closer look at the teflon. As suggested previously, it does appear that my teflon is compromised. You can see that there has been melt-compression around the hot end, and the teflon has deformed, creating a circular rut (ring) just inside the hot end before it hits the metal section. This has the effect of 'catching' any irregularities in the filament, for example when loading, the flat sharp end of the filament can get stuck in the rut and this prevents it advancing. I would also expect that the filament nicks made when the feeder skips would ALSO catch in this rut, creating a knock-on jam which makes more nicks etc etc. Catch 22. Going to think what to do next. Suggestions welcome. Mark
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