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Shock absorber bowden tube

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i want to share with you my experiences and my solutions...i received an Ultimaker about 1 month ago, 1 day to setup and 1 month to obtain a decent print...i had encountered ALL problems described there that involving extruder/bowden (plug, bowden slipping out from head, from motor and, of course, grinding...grinding a lot!)...

After some big plug i need to cut the bowden various time and, at the end, the bowden tube became too short to working properly (i had contacted Ultimaker for this problems and they have sended some replacement parts...i think can arrive next week).

While i'm waiting for replacement parts i can experiments some solutions (one more fail don't care!) but every adjustement i can apply give to me the ability to print, for maximum 20/30 mins (after that time one of the problems happen...EVERY TIME).

After about 1 week of continuos fail (and A LOT of head deassembly/assembly) i sadly admits can't be print with my printer; turn it off and watch some London 2012 female springboard...while watching it an insane idea coming from some black part of my head...let me share it to you:

A lot of people having problems with Ultimaker but the most common issues regarding:

- Jamming/Plugs (bowden pushed out from the head and material depositate between bowden and insulator)

- Slip of bowden from head/motor

- Grinding

Mumble mumble...and if this isn't the real problems but only the sympthoms of the REAL problem? What are the common thing that cause all of these problems? The pression of filament!

All problems happen because the filament contiunues to be inserted in the bowden by the motor also when it can't receive anymore and, in this case, only 3 things can happen:

A: bowden pushed out from the head (jamming and slip)

B: bowden pushed out from the motor

C: grind (if bowden can't be pushed out from head or motor)

...as i said before my bowden became too short, i can't print and this give to me the ability to try some extreme solutions: i had pick a fuel tube from my garage (really elastic and flexibile but with no resistance to temperature) cut 6/7 cm of bowden, put one end to the head (longer), other to motor and between this 2 piece the fuel tube...of course i need to fix in some way this conjunction (i had try with every glue but with no success) and use 4 pins to join them (of course the pins passing at lateral side of bowden/fuel tube not to the center!):


I hopeless try to print but incredibly...IT PRINT!!! I can't believe!!! But this isn't all: they printing really really really well!!! The prints that come out from the printer is better than ever...during the printing process the fuel tube absorbe the excess of extrusion and expand to contain (and accumulate) it...the results is a LOT more regulars and NO MORE GRINDING, JAMMINGS or SLIP of bowden...WOW!!!

To better explain i attach an image of the standard 50mm cube that i use to test the printer...the left cube has printed with standard tube (until grinding of course) the right is printed with fuel tube addon...awesome uh? :D


Yes i know...isn't a good design but hey...IT WORKS! (and, more important, this is the first thing that working and resolve all my problems!)

Finally i can print the Owen's clamp and this is simply awesome (watch yourself) AND I CAN WATCH TV ON SOFA WHILE PRINTING:


Don't know if this solution is applicable to someone (first of all you need to cut your bowden and i don't think is a good choice...but if you can't print in any way in this way you can!) but, again, i had encoutered all problems that involve extruder/bowden and 1 fuel tube and 4 pins resolve all of it (and don't think i remove this bowden also when new arrive)...

Thanks to all for your support (i'm reading really a lot of your messages...the most interesting for my problems is viewtopic.php?f=6&t=995)...i'm going to print somethings!

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Wow...really nice! By the way my most important problem is i can't print anything before the "fuel tube addon"...this mean that, unfortunately, can't print the owen's fix or everithing else can help me (it fails every time for some reason, also with simple 50mm cube as you can see)...

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Watching TV while printing is fantastic! :D

Yes, i can print little object if place it in centre of bed but i need to print somenthing larger (the reason why i had bought the Ultimaker is to print this thing)...by the way every print before fuel tube fail after max 20/30 mins (with a jamming of grinding)...with fuel tube i am printing for about 2 days (still printing now) without adjustement of screws and without jamming/grinding! I don't know if heir elasticity resolve something but seems like it absorbe the excess of filament quantity/pression and regolate the pushing into the nozzle (the objects is really more regular now!)...

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Looking at it I would guess that it is likely the sort of hose you would find on a lawn mower or around cool areas - some sort of PVC hose.

The black stuff you're talking about is probably a synthetic rubber hose, depending on the reinforcement may be used for the injector rails where there is more heat and pressure.

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I received the new bowden from Ultimaker, mounted it and nothing works again (also tried a new nozzle to be sure the problem isn't regarding it)...no more plug but A LOT of grindings (i had used about 350g of transparent PLA during weekend to try get a working Ultimaker...with absolutely no success and a mountain of half printed enclosures)...

Today, while completely desperated, i had reinstalled the "shock absorber bowden" but for my curiosity i had maked a little more change (i had used the cutted bowden piece from where i removed the plug with a Dremel..yes i know, it's a really brute force attack but i need to know):


In this way i think can obtain 3 things:

- Length of bowden can be adjusted (i can change it moving up or down into the owen's clamp)

- If the filament pushthe bowden out push out FROM the clamp and not from the insulator)

- The heat coming from the nozzle into the bowden can go out

I'm printing a big object from about 1 hour without any trouble...update coming when (and if) finished...

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But there is substantially less force on the bowden section that forms the seal now in terms of the extension and retraction, it is all taken up by the PEEK/Brass part, owens clamp and the tie rods on the head.

I would be more concerned about the difficult of inserting the filaments as well as whether the filament will buckle at that point because the tubes aren't really well supported anymore.

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I would +1 phut. I've been able to transition colors in the middle of prints (very cool for logo extrusions, but requires some trial and error) by snipping pieces of filament and creating "queues" of filament. If there isn't a complete pathway to the head I don't think that would be possible...

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