destroyer2012

I think the easiest way for you to solve the problem is to email ultimaker and have them send you new filament that is smaller. The fact that they provide filament which is too big for their own bowden tubes is a defect, and it should be corrected by them. DO THAT BEFORE YOU TAKE ANYTHING APART or else fiddling might make things worse. If you do develop a plug you should read my post here viewtopic.php?p=5842#p5842 In the future you could try getting a bigger bowden tube although I suggest getting a PTFE tube that is 1/8" ID (3.125mm) as opposed to 4mm because with 4mm the plastic will flow backwards up the tube and cause plug-like symptoms. Or you could do what I did here viewtopic.php?f=6&t=995 which does involve a good deal more fiddling and in my opinion is not sufficiently tested (I've only printed one thing with this setup so far, but I've printed a lot of things with my 1/8"ID PTFE tube.) Good luck! I'd recommend to draw a line on your bowden tube just so you could know if/when it starts moving upward.

Pray tell what fan shroud are you using, and what fan? I am using gijs' fan shroud ( http://www.thingiverse.com/thing:21182 ) with the stock fan. I haven't had any problems with my fan cooling the nozzle too much but I am running KISSlicer which turns the fan on ONLY when making outlines and turns it off during infill and support. Oh the fan is off for the first layer too. I did have an issue with the fan cooling my heated bed too much when printing with ABS resulting in warping, but I re-started that print with no fan and it came out ok. So I guess some prints (ball-like object with support) want the fan on and some prints (rectangular object with no support and a lot of outlines) want the fan turned off? You know what would be good is turning the fan on only for overhangs and bridges, as well as for small layers. Because I can't see why you would need it on, for instance, the third layer of a cube build, since the adhesion there is fairly good.

Well I set the max speed higher (to like 10000) using Daid's build me marlin website. So rest assured I am actually running 70 mm/s (or at least trying to, skipped steps aside). So could it be that everyone else is running 45mm/s?? That would make sense...

I can't understand how you guys manage to retract at 70mm/s because anything faster than 40mm/s for me results in skipped extruder steps and failed prints. THat said I am now retracting 4.5mm but because I've switched to printing ABS my stringing has gotten a lot worse. Well not because I switched to ABS but because I changed my bowden cable to be 4mm ID, which is a lot stretchier, but also ABS itself is more elastic than PLA. So I think my setup is now requiring more retraction because the filament/bowden system is stretching more than it was before. Another thing is the ABS tends to make little blobs that hang off the side of prints rather than strings. SO for example the print head oozes while traveling so all the oozate ends up wiped off the part of the print it's arriving at, and this leaves a nice row of little blobs on the smooth surface of the part, signifying where a travel move ended. THe blobs are pretty easy to remove as there's almost nothing holding them on (and ABS is less sticky than PLA) but I also get blobs at the start of travel moves because 40mm/s is not fast enough. I wish we had some way of confirming what current my motor is actually getting without fancy equipment so I can tune my system to be more like yours (as I suspect not enough current is the reason why I can't get to 70mm/s).

But if you remove the horseshoe clamp.. nothing is holding the bowden tube in! No that method only works if the clip is still attached! I didn't mean to confuse you with my picture but I am using a printed bowden clamp on top of the head which is not in the frame! I merely left the white plastic clip in to help guide the tube a bit through the too-big holes in the wood. My tubing is PTFE so it's a lot more slippery than PFA and it is also slightly bigger on the inside (1/8" = 3.175 mm). So if my filament is too big for the narrow tubing it only has to go through a bit of it, and even it will still slide even if the filament doesn't nominally fit because of how slippery the tubing is. I'm starting to think that threading the end of the bowden tube is really the best way... Lots of reprap people (not to mention ultimakers) have had success with the threading method. see ( http://www.thingiverse.com/thing:5355 ) and tantillus. I did a one hour print at 0.16mm layer height yesterday and that worked perfectly. So I think this setup has some promise, but I was also thinking of printing out the hot end mount from tantillus to use on my ultimaker since that can fit a J-head which is a much better nozzle than the UM standard. Not to mention, that hot end mount has a built-in captive nut bowden clamp which might work better than our pressure fitting (tube constricting) setup.

So I installed my 4mm ID tube and printed out the clamps you suggested (they actually printed a bit too small so were even extra super tight! Had to use pliers to get the clamps open enough to put the filament through, and I think now they are never coming off. Filament travel through the bowden was unaffected by the uberclamps) TURNS OUT that my worst fear is realized!! A plug of ABS flows backwards along the too-wide bowden tube and increases filament friction tremendously. I took my head apart and this is what I saw: My solution: Jam a short piece of 1/8" ID PTFE tube after the 4mm ID PTFE tube, right before the PEEK part. It goes right after the PLA bowden clamp holds the 4mm ID bowden tube. The short length is not clamped but held in by the ABS filament itself and the pressure from the 4mm ID bowden tube from above. I'm sure someone can design a better bowden clamp part that has a narrower barrel diameter to hold the lower tube better but for now this seems to be OK. The length does not have to be perfect because you can just make it stick out too far below the wood part. This is ideal anyway IMO because it means the PTFE tube is under pressure going into the PEEK so a traditional plug is even less likely to happen. Here's a picture of my current setup, no trouble extruding into free air (as there WAS with just the 4mm ID bowden!) Notice the extra nuts I put between Aluminum plate and wooden plate to hold the nozzle from moving up and down.

Oh yea I did that with a brand new nozzle before I extruded plastic. Had to switch it out for my old one because I screwed up the tip with a pair of flush cutters (Don't use flush cutters to remove caked on plastic!!! Heat it up don't be lazy) SO yea I would heat it up before tightening. But don't over do it! The heater barrel breaks easily. Just an eighth turn past hand tight is fine. ANd if it still leaks then maybe turn it a bit more.

Once you've got the bed level what you can do is home the head, then use the ultipanel controls to move the head to the middle and lower it down until it just touches the bed. The ultipanel will tell you how far down (or up) that is, then just remember that level and put it into your slicer. That has worked well for me before I started using a heated bed. With the heated bed you have to remember that the bed moves upward a bit when it heats up because of expansion. So just wait for it to heat up and do the same thing. As long as you are always heating to the same temp and waiting a bit before printing (or your heating takes a long time) you should be fine. I was using acrylic to print PLA which was working great but now I've switched to kapton and that works well too (PLA and ABS). For leveling I use my 1" travel indicator and this http://www.thingiverse.com/thing:16630 Just maneuver the indicator so it is almost directly underneath the nozzle, then move the head (via software!) to the four corners and adjust until the needle doesn't move much. My aluminum platform is not very flat so that approach doesn't get very far but at least i know that the curvature is evenly distributed.

I am currently running with ABSOLUTELY NO TAPE whatsoever. The secret is to screw the nozzle on so it presses up against the aluminum block, then screw that assembly tightly so it presses up against the PEEK. You have to screw it in pretty tightly, but not too tightly! Because then it will break. I did use a couple of wrenches to get it tight but i turned the wrenches VERY CAREFULLY after having finger tightened everything, only about an eighth of a turn to get the nozzle to sit tight against the aluminum block, and about the same to get the aluminum block/nozzle assembly to sit tight against the PEEK. I haven't had any leaks, but I have been extruding with ABS which has a much viscosity and so doesn't leak very much. What happens when you extrude with ABS is the extruder gets hot enough to liquefy the ABS and that fills all the tiny gaps. Then when you go back to PLA you are not having the extruder hot enough to melt the ABS, so the PLA does not get through the parts where ABS has filled gaps. This should work with tape or without. As far as print temp, I have recently gone way down in temp, printing PLA at 180 C and ABS at 230. Just goes to show that a wide range of temperatures should work.

Maybe my driver pots are turned too high.. Well in any case I can tell you that running your steppers really hot for a short period (an hour or so) doesn't seem to have any affect. My steppers survived being at 80C for several hours and seem to work fine after. WHat I'll do though is turn the pots down and flip the steppers to the outside of the UM wooden box (with drive shaft pointing inwards and engaging the short belts). That should get them out of the hot chamber and turning the pots down should help them stay cool. I don't want to put a fan on them because I don't think it should be necessary... lots of people run mendels with no fans on their steppers and I haven't heard of a single failure.

I made a tRNA from ABS! Printed with 0.15 mm layers, using KISSlicer with support enabled, fan on during loops. ( http://www.thingiverse.com/thing:21527 ) I think the ABS version looks much better. Even though the PLA version is made with finer layers, the ABS color makes it much harder to see flaws.

So how hot do they have to get for the insulation on the coil wires to melt? I can't imagine my steppers are getting hotter than 100C but probably around there, which is likely not good :/. I've been suspecting this for a while but any ideas on how to tune the stepper drivers so the motors don't run as hot? I will move the motors outside the chamber but like I said even before the chamber they got pretty hot and I seem to remember other people saying the motors only got to about a lukewarm temp.. So I gotta be missing something here, right? How hot does your extruder motor get after like an hour-long print?

So you guys had no problems with plugs forming in the interface between 4mm ID bowden tube and 3mm ID heater barrel? Or did you use a short piece of 3mm ID bowden tube material in that interface? I was thinking about doing the latter...

What happens if the steppers overheat? this http://sine.ni.com/ds/app/doc/p/id/ds-311/lang/en says the steppers have a max operating temp of 40C but I know that I have had steppers run hotter than that even before I did anything with the heated bed. My extruder stepper runs very hot, probably hotter than 40C but I didn't measure it. I don't see what could go wrong? I can understand why stepper drivers overheating would be bad but I can't see how the steppers can be hot enough to affect their electrical characteristics... can they? Can you explain what exactly the danger is?

Gotta be careful with the blower though because if it blows too much you end up cooling everything inside the chamber. I guess I have quality ABS because there are almost no (smelly) fumes. It also helps to build at the right temperature, I think if you build too hot then you get more fumes. Yes I made the clamp out of ABS (luckily before the PLA one broke! Dodged that bullet) but I discovered that the actual clamp part has to be PLA, because PLA is harder so it actually bites into the bowden tube better. Also after trying an ABS clip I was having the bowden tube slide out and that sliding made the tube really slippery right where the clip was. So I had to rough it up with some wire clippers making shallow perpendicular gouges on the bowden tube to maximize the grip. And I am now using a PLA version of the "extreme grip cone" from here http://www.thingiverse.com/thing:11864 Printing a brand new one would help with the grip too but I've been too busy printing with abs. This filament I have is 3.04mm diameter, so it pretty much just barely fits and the slight compression of the bowden tube given by that clamp is enough to affect the filament friction by a lot. If I had the stock PFA tube it would not fit at all, luckily my 1/8" ID PTFE tube is workable. I've got a 4mm ID tube on order so that should be much better when it actually gets here. I recently printed this http://www.thingiverse.com/thing:13395 in ABS with almost no warp (the rounded corners of the objects did cause a bit of warp though, really unnecessary part of that model IMO) and I attribute that success in part to the chamber but mostly to the heated bed.

I decided my ultimaker could be improved by being able to print ABS. So naturally this meant making a heated bed, but recently I went one step further by enclosing the whole thing in a bunch of oven bags, in so making a sort of warm chamber. The chamber temp is not controlled and there's no fan in it, the bags are there just to keep the whole thing warm and help prevent warping. So underneath that 3mm aluminum sheet there are four 30 ohm power resistors JB welded to the bottom. A 100K thermistor in the middle of the bed provides the temperature readout. The wool towel clipped around the bottom serves as insulation. At the bottom of my UM frame I put a small perfboard with the solid state relays that power the resistors. 120VAC through 120ohms of resistance yields about 1 amp and 120 watts of heating power. That is a bit on the low side so it takes about 20 minutes for the bed to heat up. The slow heating was part of my motivation to make the chamber. The chamber itself is made of cut up oven bags, taped along outside the walls and on top. The cross bars on the xy gantry keep the top bag from falling down and fouling everything up, which is nice. Also after its been printing for a while hot air travels up and inflates the top bag a bit which further helps prevent it from snagging on stuff. I had to take off all the PLA stress-bearing parts, including my bowden clamp which was sitting on top of the insulating bag. I imagine i'll have to take off my belt tensioners before too long too, but they don't have to bear as much force as the bowden clamp did. Still trying to work out the bugs in the filament feed system (my ABS is just slightly too fat but it seems to work most of the time) so I haven't done any enormous prints or tried to compare warping vs non chambered setups. That is what i want to do eventually though.

In my opinion its way cheaper/more fun to build it yourself. Here's my solution: viewtopic.php?f=6&t=906 I do really like using it, I opted to build it myself to avoid the enormous shipping charges/ overpriced parts from UM.

Clearly it prints something before the tube pops out so there cannot be a blockage. Do me a favor and calibrate your E steps/mm and measure your filament diameter before starting the next print. Just FYI the method of calibrating E steps/mm is to measure the amount of filament taken in (distance to a line drawn on incoming filament) WITH the hot end still connected and at temp (you are measuring how much filament is being taken in by your extruder under operating conditions). Please expand on seeing a big space. Where do you see a space? Is it between the aluminum plate and wooden parts of the head? Are you suggesting that this space forms as a result of the bowden tube popping out?? I find that highly unlikely. How far up does the black mark go? See this thread viewtopic.php?f=7&t=987 How short is your bowden tube? It should form a half-circle above the UM most of the time. If it is too short then yes that is bad. What have you done after it pops out? Did you just put it back in or did you cut it off?

That's quite a lot! So the tube comes all the way out of the white fitting? When it happened to me the bowden moved up by approximately half a centimeter and I stopped the print immediately, took the head apart, removed the plug and readjusted the aluminum plate. After I did that I didn't have any more issues with the bowden tube popping out. Then I printed a plastic bowden clamp and am now using that. Double check that the blue horseshoe clip is sitting all the way around the white fitting and is not off to the side or something. You do have the compression fitting installed in one of the drilled out holes in part 8B, right? I think the drilled out part helps the fitting to actually grab the bowden tube when the tube is pushed up, since the conical indentation makes the fitting compress. Maybe you could take some pictures to help with the troubleshooting a bit? Perhaps what we (people with working printers) should do is just print out a ton of those plastic bowden clamps and send them to people who have problems. I could probably send you one.

WHen you are saying that the bowden tube pushes itself out what exactly do you mean? Are you saying that it is forming a plug at the top of the hot end? Or is it pushing out somewhere else? If you are having the plug being formed at the top of the hot end between PEEK and bowden then what I would say is cutting off the end of the tube is not the answer! The white plastic clip does not grip the tube well when you just put it on initially. It requires some force to actually bite into the tube and form indentations that result in a good hold. That force can be applied during extrusion, in which case the plug forms and the bowden tube moves up. Normally what people do at this point is take the tube out, cut it off, and restart the cycle. What you should do instead is initially make the bowden tube stick out too far, so there's a gap between aluminum plate and wooden plate. THen, when the plug forms, just take the plug out without removing the bowden tube and just adjust the aluminum plate up until its snug again. The plug should not form a second time, because the white clip has made its bite marks in the bowden tube and is now holding it securely. If you keep cutting the bowden tube and putting un-indented tube into the clip you are not changing any condition and the plug will keep happening.

If you are getting the plug issue then her's what you need to do: Take apart the hot end and stick the bowden tube down through the white plastic clip as normal, but make it stick out about 5mm farther than it says. Then put the blue horseshoe part on the white clip and re-attach the hot end. When tightening down the four long screws on the aluminum plate you should reach a solid end point with the end of the PEEK part about 5mm from the wood. The aluminum part is NOT FLUSH in this assembly, it sits about 5mm away from the wood. Get your screws pretty tight but make sure the aluminum part is roughly parallel to the wood. Now, extrude. The extruder may jam again and form a plug. This is normal. What is happening is the force of extrusion is pushing the bowden tube up, but that is causing the white plastic clip to dig in to the PFA tubing, making a tighter grip. Take apart the hot end one last time, but DON'T disconnect the bowden tube or loosen it in any way. Take out the plug of PLA and reassemble the hot end again and make sure to get those four long screws TIGHT, but keep the aluminum part parallel to the wood. The PEEK part should now sit closer to the wood by a few mm. After I did that I didn't get any more plugs, and I didn't ahve to cut off the end of my bowden tube or shorten it or anything.

I have now changed it to suck 3.5 mm and prime 3.5 mm, at 40mm/s. So just to clarify it means it goes back 3.5mm and then forward 3.5mm, so no net gain or loss of filament. KISSlicer lets you set suck and prime seperately, which is why I am reporting it like this. Other slicers (slic3r for example) have like a "retraction" distance and "extra filament" distance, meaning it normally sucks and primes by "retraction" distance, and primes extra by "extra filament" distance, if you set it to not zero. Anyway I have noticed I have a bit of play in my bowden clamp on the extruder side probably responsible for 1 mm of retraction distance. So if you have the stock quick-fit coupling with shim (resulting in zero play) you could probably get away with 2mm. I imagine since you are extruding extra filament (suck 2, prime 2.5 right?) what happens is it leaves a big blob at the start of an outline, and then when its done with the outline the head touches and melts that blob again, causing strings.

I'd just like to update that I figured out another mod which makes retraction work way better: Putting duct tape around the filament holding screw and lever. Like this: My extruder was rattling around a LOT on retractions before. After I did this, smooth & quiet, not to mention, zero strings. So after I did that I could do 40mm/s retraction speed just fine, and I realized also that it may have been working fine before, just my code was screwed up causing it not to re-prime the extruder as much as it sucks up the filament. SO now that I fixed that AND the duct tape, retraction seems to be working well. Look at this: THe top is messy because the head kept hitting the curling overhangs, but the bottom is string free!

Here's a video of my ultimaker printing this http://www.thingiverse.com/thing:21182 That noise is pretty much how it sounds standing right next to it.

I have recently succeeded in getting decent retraction. I am extruding blue UM PLA at 180C, and retract 3mm at 20mm/s, building at ~40 mm/s As you can see all i get are tiny strings the size of hairs, which is a major improvement. Daid's Build me marlin sets the E acceleration rate to 10,000mm/s^2. We can calculate how long the retraction takes using calculus: Se = speed of extruder, mm/s Xe = distance extruder has traveled, mm in our case it's 1.5, since we accelerate half the distance and decellerate the rest. Ae = 10,000 acceleration of extruder t = time extruder has spent accelerating, sec Te = total time spent accelerating, sec Xe = int(0,Te)[se(t)*dt] distance we have traveled Se(t) = Ae*t speed we are at, given time we have spent accelerating Algebra: Xe = int(0,Te)[Ae*t*dt] Xe = (Ae*Te^2)/2 Te = sqrt(2*Xe/Ae) = 0.01732 sec Assuming acceleration is constant we could reach (and the above calc. assumes we do) 173.2 mm/sec. Or seen another way, it would take 0.005 sec to reach 50 mm/s, roughtly a quarter of the time it takes to reach the middle of our acceleration path (and an eighth of the total path), thus it's a miniscule time compared to how long it takes to actually retract 3 mm. However there's also a jerk, saying how fast the acceleration increases, and I don't know what that is. With these back of the envelope calculations it seems to me that reaching 80 or 90mm/s is entirely possible, and there _would_ be a difference between specifying 20mm/s retraction and 80mm/s. But again depending on the jerk, maybe I'm wrong. It would be nice to know EXACTLY how fast the retraction is, so we can have the retraction work for everyone.