Ultimaker 2 Spring Replacement

small tube to replace the spring in the Ultimaker 2. THis fixes the Teflon Coupler in place.

3D printer parts and enhancements

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I have been trying to get more reliable prints. One of the reasons my prints failed was because of the PTFE coupler moving during retractions, allowing small material to get in between the hot-end and the coupler. The spring is not needed anymore after the announcement that Dual Extrusion was killed off for the Ultimaker 2.

This little tube will fit exactly over the PTFE coupler and inside the print head. if you keep 1 MM of space it will also fit nice and tight.

when assembling, make sure everything is straight. apply final pressure (but not too much! with the 4 corner screws from the top of the hot-end.

I have had a great improvement in retraction performance and reliability. Looking forward to comments.


i printed this with Colorfabb XT at 30 mm/sec with fans at 100 percent, 242 degrees. printing too hot, without fans or different material might cause this not to fit. experiment untill it fits perfectly.

Materials and methods

Colorfabb XT (CLear)



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269c77b576d6f30b92552d48c7bba569?default=blank&size=40gr commented ago

Check out this version with a slot in it so you can see the bowden to make sure it is seated in the teflon coupler.

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730a061596c420c8915d9f20bd5d89e1?default=blank&size=40Marcus Wolschon commented ago

My mistake.

This made me curious and I took apart the entire assembly.

Aparently in the dim light of the 32C3 hackcenter I didn't do the Olsson Block upgrade properly.

The metal ring with the holes was not tied down deep enough. So my nozzle, heater block and PTFE liner where 3mm too high up.

730a061596c420c8915d9f20bd5d89e1?default=blank&size=40Marcus Wolschon commented ago

I meassured 7mm + the recess in the top metal part.

The spring replacement is seated properly in the metal and around the PTFE liner.

85c8811cd4fab379bdc6154f51227759?default=blank&size=40KorneelB commented ago

Hi Marcus;

first of all my apologies if i came across as hostile, that was not the intention.

what I was suggesting regarding the Nylon is not to print with it, but to use it for cold pulls.

from what you are suggesting now I agree with your mataerial choice for printing. I have testsed quite a bit with Ngen and am very impressed with it's printability and the post-print properties.

as far as the cold pull; you'll clear a lot more debris and old filament when using Nylon. please also see this:


730a061596c420c8915d9f20bd5d89e1?default=blank&size=40Marcus Wolschon commented ago

Why are you suggesting me to get Nylon?

You don't even know what I'm printing and what properties is shall have.

I never used Nylon, have no experience with it and from what I hear it doesn't stick well to the glass bed. That doesn't sound reliable enough for technical parts and is way too string to be easy to sand and polish by hand for artistic parts.

I print technical parts unobserved. Reliability is key. PLA/PHA has shown to be extremely reliable and now I have 2 large 2.2Kg spools of nGen based on the promise that it is even more reliable. I'm still in the progress of getting it to work and proving that reliability.

For artistic parts I have finally completed all preparations to start testing 2 kinds of technical wax. A material I have some experience with on my CNC mills.

I'll meassure my hot end. Maybe the dimensions are different.

I'm pretty sure the top part did fit into the recess properly but I will check again after hours.

85c8811cd4fab379bdc6154f51227759?default=blank&size=40KorneelB commented ago


probably spending too much time on this but here goes;

the space between the 2 hot end holders is 17 mm as per the cooling rib spec :


the bottom is flat, but the top has a 3 mm clearing (as per belows post) making the total gap 20mm.

the hot end Coupler has a 4 mm "neck" as per https://github.com/Ultimaker/Ultimaker2/blob/master/1310_Hot_end_Isolator_(x1)/B1310-Z2P-A%20Hot%20end%20Isolator.PDF . then the PTFE coupler has a 4.5 mm neck. adding the 1 mm spacing between them leaves a 20-4-4.5-1 = 10.5mm area to bridge. the gap should be between 0.5 and 1 mm so keeping any printer tolerances into account the spring replacement i designed should be around 10.5 to 11mm. looking at the STL above, it says it's 11mm..

if it would be 3 mm too long, the stl file above should state it's 14mm..

so I think you might either be installing it incorrectly or you might have printed it incorrectly..

85c8811cd4fab379bdc6154f51227759?default=blank&size=40KorneelB commented ago


are you sure the printed spring replacement actually slides into the top hot end holder?

you keep saying it's 3 mm too long, and the gap in the hot end holder top plate is exactly 3 mm's deep... https://github.com/Ultimaker/Ultimaker2/blob/master/1307_Hot_end_holder_top_(x1)/B1307-Z2P-B.PDF .. can you verify?

85c8811cd4fab379bdc6154f51227759?default=blank&size=40KorneelB commented ago

well, the filament responds quite differently, i've run several tests with it as well and it does seem to bulge out a bit. 3 mm is quite a bit, but if i read your blog correctly, you've been having quite a bit of extrusion issues, that might be a cause?

filaments do NOT produce the same height, all filaments respond differently.

I have 3 Ultimaker 2s myself with this spring replacement installed and I've personally installed this in multiple other Ultimaker 2s with a lot of other people also printing and installing it. you are the first one to mention that it's 3 mm too long.

i'm also using the Olsson bock so that's not the issue.

either your print was wrong or my design is wrong. now all signs post to that my design is not wrong ;)

anyway, in Cura, if you just change the sizing and shorten it by 3mm with the "shape lock" off, you can lower the height by 3mm.

are you sure you tightened steel coupler enough on the head? you might have a large gap between the coupler and the PTFE coupler..

furthermore, i would recommend to get some nylon and stop performing cold pulls with PLA and\or NGEN since it is most likely to break and you will get way btter results with Nylon...

730a061596c420c8915d9f20bd5d89e1?default=blank&size=40Marcus Wolschon commented ago

I do not have XT Clear, I never used XT at all and HOW should another type of filament make the object 3mm shorter?

All filaments should produce the same height.

It is serveral millimeter too long for an Ultimaker II toolhead with the usual Olsson Block and the original Ultimaker glass fiber reinforced PTFE liners.

and the toolhead can not be assembled.

85c8811cd4fab379bdc6154f51227759?default=blank&size=40KorneelB commented ago

then there's your problem..

try XT Clear with the properties I've mentioned above..

730a061596c420c8915d9f20bd5d89e1?default=blank&size=40Marcus Wolschon commented ago

I used nGen since I'm currently experimenting with it.


85c8811cd4fab379bdc6154f51227759?default=blank&size=40KorneelB commented ago


so am I :)

so what material did you print the part with?

730a061596c420c8915d9f20bd5d89e1?default=blank&size=40Marcus Wolschon commented ago

I'm using the standard Olsson Block on an Ultimaker II (extended).

I can not insert the 2 bolts of the"top portion" fully without sanding down your part heavily.

If I don't sand enough I may juse barely insert the bolts but the nozzle will be at an angle and touch the thin steel sheet.

85c8811cd4fab379bdc6154f51227759?default=blank&size=40KorneelB commented ago

@Marcus Wolschon

did you print this in Colorfabb XT with the specs i mentioned above? if you use a different material or different settings you will get exactly the issues you mentioned.

I have now printed this a lot of times, and so have many others without issues..

the length is good, the top should fit inside the opening in the top portion of the head. if you don't fit this in, and it will be a tight fit, it will be too long.

730a061596c420c8915d9f20bd5d89e1?default=blank&size=40Marcus Wolschon commented ago

This is too long.

The inner diameter is a tight fit and needs a round needle-file to make it fit.

The length needs to be reduced by serveral millimeters.

Else the hotend will not fit together anymore.

While doing that, you need to keep both faces perfectly flat (to not damage the PTFE) and perfectly parallel (so the nozzle stays in the center of it's hole and doesn't touch any side=loose heat).

...no easy task.

730a061596c420c8915d9f20bd5d89e1?default=blank&size=40Marcus Wolschon commented ago

Does it work well?

Any problems?

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