snowygrouch

Ummm well your post isnt very clear which doesnt help. "the extruder does not move" then later.... "the ultimaker prints fine" Also if you upgraded firmware, have you tried putting the old one back in ? Its not easy to diagnose anything with: no pictures no Gcode no firmware number

If you can I think 2 screws is better, how often do you need to adjust yours ? Except when I am modifiying something, I have adjusted them about twice in 6 months... C.

I changed the VmaxE to 35 (is 25 in new Marlin). This fixed the retration, but due to another change in Marlin I could only get reasonable speeds by multiplying all previous travel and print speeds by x0.6 No word back from KSlicer if there is a way to get it to work with Marlin for dual extrusion....hopefully this means he is working on it.... So at present I can print in dual sucessuflly with CURA 12.08 and nothing else. However as Daid says, at the moment the results are not really UMaker standard.

No idea Ian. Incidentally latest problem to fix is that the most recent Marlin firmware results in different retraction speeds because the Vmax E value is changed from 45 to 25 in the firmware (there may also be other things that are causing the issue too, in the firmware). So will sort that out over the coming week, I just did some test pieces and suddenly the retraction was completely rubbish and my KS prints came out looking like the useless rubbish that Netfabb used to make... Anyway, I will put all details on my website as and when I suceed with this, I think some others have the same issue (independant of the dual heads) so I am sure that collectively a good fix will be found. Regards C.

This is a great thread, my opinion would be that if you apply back pressure to any drive system you will inevitably get reduced extrusion. This is because of the highly elastic nature of the material being worked on. I think that in the short term, a big improvement can be to have two driven knurled wheels, rather than one. However I think that really great results can only be achieved by having a 3rd wheel with a rotary pot (or something) just "downstream" of the knurled drive wheel, that will measure the linear speed of the filament passing through. This would also really need to be coupled to a sensor detecting filament diameter in real time, to get really perfect extrusion at all times. I would be happy to help to do some mechanical design on this stuff, but I have no idea how it could be integrated into the functioning of the firmware/arduino etc..... C.

Very glad I found this topic, because I updated my firmware from the latest from Github (then modified it so the 2nd extruder worked), but now find that the retraction performance in Kisslicer is now RUBBISH. I thought I was going nuts an imagining it for a while, spent ages going over print temps, print speeds and slicer settings.... However, can someone confirm or not if there is anything I can mod in the firmware that will restore my retraction performance ? Or do I need to put the old firmware back in, and wait for a fix ? C.

I agree 100% with Joergen, its way too much messing around to find that stuff. Not everyone enjoys wading through miles of Github stuff and reading through release notes....

Me too....consider this a "pre-order".

Just make sure you watch the printer working when you have problems like this. Otherwise diagnosis is alot harder. If you can see the printhead hitting the warped egde, and you hear a BOINK ! sound - probably the belt skipped a tooth. If the motor is skipping you will also hear a very unhappy grumbling sound from the motor. When its a phyical problem like this, sitting and watching is very beneficial. If you are too buisy to do that then get a webcam and film your prints (with audio). Then if the print fails you can just quicky skip through the video footage to find what happened. C:

Looking at your print, my best guess is that the print is warping upwards (this is always worse when you have large angled beams like your model has). This has happened to me several times, what occurs is that the print warps - the printhead nozzle then hits the upturned edge on one of its moves with such force that a motor skips steps. Im not saying a slicing error is impossible, but I have not heard of any such problems with 13.03 (and have used it myself recently). Which leads me to suspect that its very unlikely to be the problem. Solving it is not easy, but you can try the following things. 1) rotate the STL model so that the parts where it warps UPWARDS are at a 45 degree angle to the YX axis. This just slightly softens the blow when it does hit (because the force is then distributed between both motors). However this only really works when printing roughly rectangular geometries. 2) Try printing the part in a different orintation, or separating then bonding together after printing. 3) Search out threads here on lowering warping and follow tips in there. 4) I dont know if the latest CURA has the feature, because I only just started using it a few days ago, but the latest Beta version of Kisslicer has a "hop" feature. This lifts the printhead during moves so that the nozzle does not hit the print. I have no tried this feature so cannot say if its implimented correctly. 5) Increase your layer height. This will give more clearance for moves during printing. I would suggest 0.3 to be max sensible height. 6) Decrease the distance between support and model, such that the support "ties down" the angled beams from moving upwards. Makes removal harder of course. 7) Edit the STL to have perhaps a small diameter post as part of the model that achieves the same things as #6 I mainly use Kisslicer, so perhaps one of the CURA experts can come in with more specific suggestions tha will be helpful to you. C. EDITS: Couple of extra thougts. 8) Although fan cooling as a whole, does make the part "warp" more - LOCALLY more cooling will lower the warping of thin edges of the kind you have on those leading edges of the 3 angled beams. So perhaps try to increase cooling there. 9) Increasing infill % might give the beams more stiffness and be less liable to warp. However how it will behave thermally is highly "form dependant" so its not a rule that will automatically be guaranteed to make the leading edge of the 3 round beams stay flatter. 10) I dont know if CURA has it (I think it does), but you might want to increase the "minimum layer time". This gives things like thin edges a bit more of a chance to cool... probably its set to 5 seconds or something right now. Try increasing that a bit...

Looks like hopefully an improvement, looking forward to seeing results. I dont think the standard ones have a particuarly well cut toothform...so might be a good jump in removing play in the system.

Looks great ! The trick to determining what the likely cause of a plug is, is the time it takes to develop. When you were getting almost instant plugs, this is a sign of a physical particle blocking the nozzle. When you get the "traditional" plug, caused by *blah blah blah look at the threads on that stuff * it will develop slowly and starts with slight under extrusion and can take hours of printing to result in a full blockage. Glad it works.

Yes, but its not very nice. Take off the nozzle, and hold it with pliers or whatever over a candle flame for a few mins. Unless what is in there was metallic blocking it, it will get carbonised and turn to ash. Clean it up as best you can, reinstall and flush PLA through by turning the extruder wheel by hand with the hotend at 220C or whatever. Probably you will get black rubbish coming through for the first few cm of filament. Also what I have done when I got a 2nd hand V1 hotend to build my dual setup (it was full of old solidified PLA). was to put in a vice, and hold a solering iron against the nozzle. Then I was able to pull the "plug" of PLA out with tweezers. This pretty much pulled out most of what was in there at the same time.

I am highly suspicious about your hotend temp. If you can be bothered to do so, I recommend boiling a cup of tea (obviously dont bother to put the tea in) lower your bed to the base and immerse the thermocouple in the just boiled water. Obviously it should read about 95 Deg C by the time you put it into the mug and did the rest. Just one possibility....

Hi Daid, So this looks officially like there is a bug ín Dual Extrusion when using it for support structure somewhere between ver 12.12A and 13.03 Regards C.

I have looked a bit about the "should we go to ARM" stuff on the net. Which in principle I am very keen on (in theory), have always been a massive fan of ARM CPUs apart from anything else. However before I had an ARM Ultimaker I would much rather have first: 1) Upgraded CURA with new slice engine in background 2) Really good dual extruder support So there you go, or to put it another way, #1 and #2 there have actually stopped me from being able to do what I need to...and the ARM board would not fix either #1 or #2. However I am sure its something (or similar) that will need to happen in the next couple of years, as the complexity of the control logic increases.

1) what kind of plastic are you trying to print 2) Which program are you using to slice 3) how big is the part (ie now long are the prints) 4) What temperature are you trying to print at 5) Do you have the fan on, if so after how many layers 6) Did you make sure that there are no gaps in the hotend when you assembled it 7) Have you checked you assembled the hotend correctly ? You can get the orientation wrong I believe with the new hotend 8) what print speeds are you using 9) Pictures help alot,...take pics of your hotend so we can see how you have assembled it We are not really interested in what you did to fix the blocks, but more what you were doing when they happened. Also, there are ALOT of old threads on this stuff...have you checked them yet?

Yes the support in CURA is fairly fluffy, however it was so thin it was just turning into a ball of fur. I had to tweak the flow to 120% in the Ulticontroller to get the layers to actually stick (this is with E set to 835) (so to clarify the main part was printing fine, so after I tweaked the flow up, the main part was slightly over extruded but the support was then just about ok). For people with 2 identical extruder setups this will be much less of a problem I think

If you dont mind taking the thing apart a bit - boiling water is always a winner for testing TC, because you know its basically exactly 100 Deg C.

It worked with my own firmware build, and Cura 12.12A Thanks for the tips.

Is now working using CURA 12.12A (apparenly later versions have some issue when selecting the print support from 2nd extruder option). Built own firmware as Daids builder website is down. Some odd tool movements shown here.... Support (in blue) has printed very poorly as I cannot edit "steps per e" for each extruder indepedantly. My "top down" feed for extruder 1 likes about 835 steps but I think the 2nd extruder with the standard position bowden needs nearer 860 steps. So the support is very under-extruded

All working now, built my own firmware and switched to CURA 12.12A However next problem is how to set the "steps per e" for extruder 1 and 2 independantly...

Ah HA ! Ok, that would certainly be one issue....haha Will change the firmware tonight as you suggest and see if anything good happens. Thanks ! C.

Hi Daid, Yes thanks, that is what I want to achieve. Hopefully can get there in the next few days. C.

I will try the older Cura tomorrow, still messing around with the TOOLCHANGE gcode window right now.