Very high Friction in the Bowden tube

[polymorph 1]

I'm trying to get the filament out to start over, so I can print that new friction plate with a ball bearing. However, I can't get the filament to come out. I've even turned the heat up to 225C and let it sit for an hour to get it warmed up all the way through. I pulled with pliers 'til it snapped off. From the way the tubing moves, it is jammed up in the head.

Any suggestions?

BTW, I'm AlienRelics and Polymorph. I didn't mean to log in twice... I forgot I'd already created an account and made another.

[gael 0]

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

[polymorph 1]

There is that step in the instructions where it says to push the tubing so it sticks out 8mm. Then after you pull it back, it says again emphatically that it must stick out 8mm. But pulling it back in the plastic compression fitting slides it back 2mm. So I pushed it out another 2mm, so it stick out 8mm -after- taking into account the pullback in the compression fitting.

Was that wrong? Have I compressed the end of the tubing so it constricts too much?

http://wiki.ultimaker.com/Ultimaker_rev ... usion_head

Sigh... looking over it again, I see it does -not- say 8mm after pulling it back. I also see I mistakenly put the end -with- the blue tape in that end.

Now if only I can get it apart to start over.

[futurejames 0]

I looked up bowden tube size:

https://shop.ultimaker.com/en/bowden-tube.html

Ultimaker ships it out 67cm long (26.4")

[alaris2 1]

well done steve. you made the same mistake I did. we were too clever and tried to compensate for the 2mm but what the instructions fail to say, is that they already took that into consideration.

careful measurement shows that after correctly applying the horseshoe clip, the tube now only protrudes by 7.1mm. but this works, so don't worry.

nik

[polymorph 1]

I wonder what difference the end with the blue tape makes.

Well, this is progress. Tonight I'll heat it up and take the head apart. Cutting off a few mm from each end shouldn't cause it to be too short. I do have the other tube on the way, at least.

My big rush is that this weekend is a Maker Faire in Seattle, WA and our club, OlyMEGA has a big space there. Fortunately I'm not the only one displaying something, but I would like to have it printing. I was hoping to get my little CNC machine working, too, but it looks like this may take all my time before the faire.

[Daid 306]

 

I wonder what difference the end with the blue tape makes.

The blue end has been drilled wider, so it's easier to stick the filament in it from the extruder side. Putting this at the hotend side will create plugs.

[polymorph 1]

I wonder what difference the end with the blue tape makes.

The blue end has been drilled wider, so it's easier to stick the filament in it from the extruder side. Putting this at the hotend side will create plugs.

Sigh... so I've heard. :'/

I'll keep that in mind when I reverse it, and rather than trim it perhaps I'll push something tapered into it to rewiden it.

[futurejames 0]

Now it seems to work fine and I can print with the indented 3.0mm filament...

Hi Gael,

Are things still printing OK with the 3.00mm filament and the bigger bowden tube? I found some cheap PLA but it appears to be 3mm, and want to know if it'll work with the bigger tube.

[gael 0]

Hi!

I have been accumulating about 20 hours of printing since I upgraded the tube without any jaming.

I also have less stringing (which is logical) and unloading/loading the filament is a breeze...

++

Gaël

[polymorph 1]

Hm. Forum didn't post my message asking for advice on removing the tubing, I didn't notice. Just as well, figured it out.

Partly disassembled the head. Took the long bolts out, heated it up, head pulled right off the tubing.

Took the blue clip from the compression fitting. Holding the compression fitting down, but the tubing will not pull out. I'm afraid to use too much force for fear of damaging something.

The compression fitting dimpled the tubing, and the filament still inside had partly melted, filling it so the still expanded portion below the compression fitting could not compress. Got both ends of the tubing free, pushed the filament out rather than pulling it back. A bit more effort and the tubing came out of the compression fitting.

I had to pull -really- -hard- to pull the filament out of the tubing. That does not seem right. Checking a few places on the filament, I find it is oblong so it is up to 3.05mm diameter in places. I'm sure if I check more thoroughly, it is larger in other places. Making the tubing that tight a fit seems like a mistake. With 4mm ID, no tapering of one end would be necessary. I didn't have any problems inserting it into the untapered end, anyway.

I can clearly see, now that I know to look for it, that the inside of the blue-taped end of the tubing is tapered inside.

Looking at the compression fitting on the Bowden feeder end, I don't know how I'm going to get that out. It is meant to be a one-time, permanent connection. I may leave it where it is at, and trim the end at the heater head beyond the taper.

I don't understand why it would be such a tight fit. Reinserting the previously driven filament, I get it about 1 ft (sorry, 300mm) inside and I can barely push any more by hand. Are only a few of us having a problem? Did they recently change tubing? I got mine a few months ago. I feel like we need a 3 piece driver using curved pulleys like on the MakerBot driver, so the filament is kept mostly round and it doesn't have to dig in nearly as much.

I think some of the friction is from it being out of round, and some is from the very rough, toothed surface against the inside of the tubing. Without the back pressure created by me putting the tapered end at the wrong end, less pressure should be required. The first thing I think I'll print is that pressure plate with a ballbearing holder, that should also lessen friction considerably. All meaning the filament should have a lot less flattening. Then later I want to make the Bowden Feeder replacement that uses MakerBot's half-round pulley driver.

[joergen 2]

Took the blue clip from the compression fitting. Holding the compression fitting down, but the tubing will not pull out. I'm afraid to use too much force for fear of damaging something.

The compression fitting dimpled the tubing, and the filament still inside had partly melted, filling it so the still expanded portion below the compression fitting could not compress. Got both ends of the tubing free, pushed the filament out rather than pulling it back. A bit more effort and the tubing came out of the compression fitting.

I had to pull -really- -hard- to pull the filament out of the tubing. That does not seem right. Checking a few places on the filament, I find it is oblong so it is up to 3.05mm diameter in places. I'm sure if I check more thoroughly, it is larger in other places. Making the tubing that tight a fit seems like a mistake. With 4mm ID, no tapering of one end would be necessary. I didn't have any problems inserting it into the untapered end, anyway.

I can clearly see, now that I know to look for it, that the inside of the blue-taped end of the tubing is tapered inside.

Looking at the compression fitting on the Bowden feeder end, I don't know how I'm going to get that out. It is meant to be a one-time, permanent connection. I may leave it where it is at, and trim the end at the heater head beyond the taper.

I don't understand why it would be such a tight fit. Reinserting the previously driven filament, I get it about 1 ft (sorry, 300mm) inside and I can barely push any more by hand. Are only a few of us having a problem? Did they recently change tubing? I got mine a few months ago. I feel like we need a 3 piece driver using curved pulleys like on the MakerBot driver, so the filament is kept mostly round and it doesn't have to dig in nearly as much.

I think some of the friction is from it being out of round, and some is from the very rough, toothed surface against the inside of the tubing. Without the back pressure created by me putting the tapered end at the wrong end, less pressure should be required. The first thing I think I'll print is that pressure plate with a ballbearing holder, that should also lessen friction considerably. All meaning the filament should have a lot less flattening. Then later I want to make the Bowden Feeder replacement that uses MakerBot's half-round pulley driver.

If your filament is this much deformed, you should really dial back on the filament tension screw, as it is counter productive in many regards.

the tube has a nominal ID of 1/8in (3.175mm), which leaves enough room for most filament diameters (ranging from 2.8-3.0mm), and even a 3.1mm section should be able to still move reasonably through the bowden. a 4mm ID tube (as suggested elsewhere), isn't really the right solution for this problem, since it would be much easier to simply not deform the filament when it's running through. I am still using the V2 bolt, and I have no issues with skipping/grinding (I also don't do high pressure prints right now, but will go back to it).

tapering it on both end isn't wrong, and putting the tube in the wrong way, isn't a bad idea:

Se http://wiki.ultimaker.com/Jamming and http://forum.ultimaker.com/viewtopic.php?f=7&t=102

this allows for a much higher junction compression in the top part of the PEEK.

Testing how the filament slides past the interface between bowden and brass tube by hand is absolutely mission critical, and "by hand" i mean by hand, not pressing a button in printrun.

in regards to the tube, it can really move only downwards through the clip, not in the other direction, so it is much easier to just push it all the way through and refeed it from the top. just don't forget to clean the metal teeth in the retainer clip from any PFA debris, and make sure the section you are insering is free from significant scratch and bite marks.

removing any filament from the tube should be too hard once you have taken it out. use some virgin filament to push it out in the direction that is shorter or easier.

[polymorph 1]

It was slipping, or I'd not have turned it up that high. I agree that it is counterproductive!

The tapering shown in the link is more of a countersink, something I think I'll do after trimming the end.

I'm hoping that fixing the taper thing and printing a ball bearing pressure bearing will reduce the force required. Perhaps I need to turn the temperature up slightly, I had it at 210 but it will melt the filament quicker at a slightly higher temperature.

[concreteturtle 0]

Hi Guys,

I have exactly the same issue with my new kit. I can force about 2 inches of the provided filament into the flared end of the bowden tube, but then it get too hard to push even with both hands!

Maybe the bowden tubes in the recent batch of kits is too tight?

Is there anything else I can do to get up and printing?

I'll send a message to support and let you guy know what I find out.

CT

[polymorph 1]

I could not remove the tubing from the fitting on the motor end, so with a brand new single edge razor blade I trimmed off the tapered part. Then as suggested, I put a slight internal chamfer in the end of the tubing where it pushes into the brass, but using a countersink bit because it gives a much cleaner finish than a drill bit.

Now it moves so smoothly that only a fairly slight push by hand with the head at 210 will feed plastic easily.

I trimmed the end of the PLA filament with a flush cutter. If you use regular wire cutters, it will mush out the end into a chisel shape with wide ends, and you may experience the symptoms you are getting.

Sigh... but now I have software problems. I'm using Cura, which worked before, but now it is extremely finicky about connecting to the com port, or it freezes while trying to send the Gcode, as soon as I try to set the idle temp or move any of the steppers. But that's a problem for another thread.

[futurejames 0]

My new PFA tube just got here. 4mm ID 6mm OD.

After a bit of monkeying around, I got things working. I can tell you both owen's bowden clamp and pit3k's bowden clamp are mandatory. Print out whatever is bigggest/strongest from the provided STL files.

So far so good. I'm going to try some slightly larger diameter PLA and see if it can handle it.

[polymorph 1]

My laptop is suffering from Windows rot. My netbook connected without problems (cross finger, knock on wood) and printed a new ball bearing pressure plate. Next I think I'll print both of the parts you mention so I can use the 6mm/4mm tubing I bought.

I also discovered that my temp was far too low (210C) and now have it at 230C. I did find that I need to print the outline 6 times to prime it properly, as it tends to dribble when just sitting there hot before the print. I also bought a digital micrometer good down to one micrometer, it works better for this than my digital caliper to measure the filament.

Also, the pressure on the feed bolt is somewhat sensitive, in that too much causes too much friction on the pressure plate, so there is a relatively narrow range of pressure that is just right.

I have other ideas to talk about but I should not take this too far off topic.

[alaris2 1]

thought I'd add a 'me too' to this thread.

my machine has been working perfectly for maybe 30+ hrs, then suddenly tonight it stopped feeding.

the symptoms are worth being aware of - the shoelace pattern on the filament is normal, indicating the extruder is working correctly, apply some manual force and the filament does move through, but let go and it stops. the extruder doesn't have enough force to move the filament through.

the reason? filament had varied slightly from the 2.88mm it started at, to 3.01mm at this point.

I removed the filament to see exactly what gael posted a photo of earlier in this thread. it was hard work pulling the filament out - not just out of the hot end but out of the tube.

conclusion: the fault is definitely the ID of the tube. as the filament varies the print quality varies (I've posted photos of this before) - this may actually be because of increased friction I now realize.

I really don't want to have to mod the hot end - but I see no alternatively (other than throwing this filament away).

does anyone have any nice hotend mods they'd like to share - if I'm making one change I might as well make a few..

has anyone made a quick release interchangeable head yet? I saw Daid working on something related a while ago..

[joergen 2]

conclusion: the fault is definitely the ID of the tube. as the filament varies the print quality varies (I've posted photos of this before) - this may actually be because of increased friction I now realize..

well, it is very unfortunate, but it seems a complete batch of PFA tubing was bad from the manufacturer... it happens, since the OD is very easy to measure during manufacturing, but the ID isn't. I guess I got lucky when I bought my PTFE tubing here in the US, since they are quite rigorous with their quality control... it is basically the same as with filament: cheap ones vary greatly in diameter, more expensive ones are more constant in their dimensions. you get what you pay for.

 

I really don't want to have to mod the hot end - but I see no alternatively (other than throwing this filament away).

does anyone have any nice hotend mods they'd like to share - if I'm making one change I might as well make a few..

Taylor made a new part to replace the PEEK, and Scott Mayson has a mod on

http://www.thingiverse.com/thing:20535

Since they both reflect a discussion we had earlier: http://forum.ultimaker.com/viewtopic.php?f=6&t=184, I can highly recommend this mod.

the easy part of this mod is that you can make the part yourself, with modest tools (M6&M7 tap + M7 die, plus access to a lathe or at least a drill press, and a 5/8in PTFE or PEEK rod). or you can contact taylor, and see if he can sell you a part. totally worth the effort, since I can't think of a scenario where the M7 connection could ever pop out again.

[ataraxis 51]

hey gael! do you still use your 4/6mm tube? did you had any problems with it so far?