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keukpa

It's all in the PTFE Coupler!!!!

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OK,  (Stick with it, it ends well!)

So I've had my Ultimaker 2 for about 6 months now, and I've never really been that happy with it. Skipping on extrusion, so I make it hotter, stringing on extrusion, so I make it cooler, skipping, and on and on....

Then I kind of get this sorted and the next problem is that after a successful print, in order to be able to print again, I need to remove the filament and CLEAR the entire hot end, which means taking it apart....

about 50% of prints would fail 1/2 way through.... not going good, my other printers are far better, yet I've seen people print with this and I think why can't I?

So, I'm the kind of person that likes spares of EVERYTHING, you know, just-in-case... so when I got my printer I bought a full hot end replacement kit....

Playing about with the printer a few days ago, I thought I've had enough....and I was THOROUGHLY cleaning the head and thought, hmmm the isocoupler thing looks a little crap, so I got out my new spare, and looking at the shaft of the two PTFE Couplers, my current one was much wider than the new one... which also looked 'better quality' so I thought I'd swap that over...

Well..... OMG!

What a difference this has made, I have printed and printed and printed since this simple swap, and not had ANY problems, this is now a FANTASTIC printer... I'm just sad that the initial PTFE that came with my UM2 was so poor.

So, the point of this post, don't give up, if you are having similar problems as me, get a spare PTFE and swap it over.... £11 'upgrade' and my printer is sweet!

Cheers,

Keukpa

Edited by Guest
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I have a problem with my PFTE thing sliding up and down during atomic pulls which in effect renders me stuck to not being able to do them anymore which is worrying as i cant unblock my nozzle anymore. Its like the spring inside is not doing its job? do i need a new spring or something? have i installed it right? The filament i pullout during my failed atomoic pulls even looks weird, like filament coming out from within the filament? alien filament? I really need to sort this though as i have a massive job coming up, and dont really want to buy a new print head unit every time i need a new PFTE coupler. I tried to fit it the best i could, but even though it looked identical to the old one, it doesnt seem to fit the same at all and sits waaay to high still... :( ive been using it a fair bit since the change, but am dreading a serious nozzle block as ill be doomed then.

Here is the result of an attempted atomic pull

20150825_122428.thumb.jpg.f5273b40ec23e769a5ccdedec5dde4a1.jpg

compared to what it used to look like...

20150426_145409.thumb.jpg.c3c0b9fd35e088bdfe7df3faf94bd42d.jpg

20150825_122428.thumb.jpg.f5273b40ec23e769a5ccdedec5dde4a1.jpg

20150426_145409.thumb.jpg.c3c0b9fd35e088bdfe7df3faf94bd42d.jpg

Edited by Guest

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OK, my coupler moves so much now after changing it? i am now completely screwed. If i cant fix it, then my time with this printer is over unfortunately all because of a 10 buck part, great. im seriously annoyed, and am getting tired of taking apart the print head. I have no idead why the coupler moves so high effectively blocking me from doing atomic pulls, but it ok-ish during printing. If anyone has any suggestions i would greatly welcome them as otherwise my time on this forum and printer are over for good... ill have to start looking for alternative printers without the stupid PFTE thing.

my dumb coupler.

20150829_134712.thumb.jpg.2a029e92d72dd96980fc6fda2382dabe.jpg

Im getting tired of tweaking and was hoping i did enough, i had just started a massive project so im extremely annoyed hence this ranting post, but now fully understand why so many people have poor quality prints. As the title puts it so correctly its all in the damn coupler. :(

20150829_142301.thumb.jpg.ab38996aa1a9e190feea98349db59ce3.jpg

this is during printing? why is the coupler lower now? I can only do atomic pushes now not pulls, lol. so fricking annoying. I get that damn clicking noise again now that i cant do atomic pulls anymore, im gonna smash the printer before long if this continues.....

Do i need a new spring.....? I cant see any reson why the coupler would need to move at all. Why isnt the design of it don to prevent to moving. This has single handedly destroyed my entire perfect image of this printer.

20150829_134712.thumb.jpg.2a029e92d72dd96980fc6fda2382dabe.jpg

20150829_142301.thumb.jpg.ab38996aa1a9e190feea98349db59ce3.jpg

Edited by Guest

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Thanks for the reply, I wasnt aware it could be done any other way. there was no gap when i installed it, but as soon as i attempt an atomic pull, it moves up? like the melted plastic inside is forcing the ptfe coupler to raise. I would love to solve this so i can actually clean the nozzle, as now i am having no choice other than to print with a blocked nozzle, and the results are not that great to be honest, but seeing as i have a tight deadline, my only other option would be to buy a new nozzle or entire head assembly, and then to examine this one in the meantime.

Please correct me if im wrong, what you are saying is to unscrew the stainless steel coupler put the pfte coupler on it and then screw it onto the heater block. I think i did that most recently, but I noticed that the more i twisted the stainless steel coupler the pfte coupler would rise? which left me at the problem im at now?

My main question is, why does the PFTE thing move up, or at all? and is there a way to install it to prevent this? I will have yet another look after my current print is ready, but am slowly loosing faith due to most likely doing the same things wrong, not really knowing how to do it right even after looking at the instructions on the web. If only there was a clear video showing how to do it right? It doesn't take long to do and is essential so i dont know why anyone from UM hasnt done one to help those with this issue. But it looks like i'm the only one :( (even though i doubt it, i reckon other people just carry on printing in a poor quality and just not knowing why.)

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Ill post a video of me doing it all, and if you could tell me what im doing wrong, i think thats the easiest way as i cant see how putting on the coupler before or after the stainless steel coupler will make any difference as it moves later regardless. Could i replace the spring with a solid cylinder of steel, to prevent the thing moving up, is the spring really essential? im not too good with taking things apart, and putting them back together, but have managed in the past with a bit of common sense but this puzzles me seeing as i essentially just replaced one part that didnt move for one that now does, causing me endless problems.

Edited by Guest

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After extensive nozzle cleaning and atomic pulls. i've come to the conclusion that the coupler is at fault after like 1 months replacement, great. Not too happy there, now i need to buy some more. And the gap between the coupler increases if i push the filament in too hard, and the plastic melts outwards and forces the coupler up. trouble is during long prints the pressure can occasionally slowly build up and push out against the coupler and hardening causing a slow jam and there is nothing i can do about it. Seriously worrying. Even after like 20 atomic pulls the dreaded clicking is happened again, which to me is a sign of a dying coupler or blocked nozzle. So back to my emergency style of printing with a damaged coupler for me again. This coupler business is such a drag, and my worst experience regarding the UM2, it causes all my problems. Especially when printing large objects which i needed to do recently, ill just have to sand them harder by hand. If you print a lot then its just a matter of time till this issue affects you too, or it already is...........:( Good times are over for me....

Edited by Guest

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If plastic is getting between the coupler and the hotend there must've been a gap between them to start with I think. Make sure that the top of the heaterblock where the PTFE mates with it is completely clean before installing the PTFE and make sure that it is seated all the way down.

I can't remember seeing/hearing anyone having a problem where the PTFE moves up when you push filament down. The other way around though happens quite a bit.

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Ill film it in action, very weird. At least my method of damaged coupler printing is working for the time being. Otherwise my job is not gonna happen... If i push filament in it goes up, and if i take the filament out it goes down...weird. makes atomic pulls almost impossible.

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Here is my coupler going up when i push in filament for an atomic pull, and then back down when i take it out? i cant print anything anymore without a jam, so i have no idea what to do. change mozzle, change head unit,......no idea. and i just started a massive project, i'm totally screwed. cleaning doesnt seem to help. maybe 50 atomic pulls?

 

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@martijn - you need to see this.

So, this is hydraulic pressure, a backlash of liquid plastic from the block inside an upwards.

It is like @iroberti writes, very important that the the things connect:

Steelcoupler all the way down (lifting the block inisde) to increase spring pressure,

totally clean hote-end-top-end so no leaks between teflon and block.

Could also be due to too large block entry hole (manufacturing mistake),

or (really!) too thin filament.

There is a fix for this: The "Korneel Spacer".

Find it in the forum. Essentially, it replaces the spring and makes all

hydraulics in your case static = nix more problems.

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Yeah I was thinking about something like that, but Im not sure why its doing that now only when I have replaced the coupler. The first time I admit I may not have cleaned everything perfectly, but the second time I cleaned everything to a perfect finish before I installed everything correctly and made sure everything was touching what it needed to touch and all that. I really didn't want to waste time ordering new components but it appears I have no choice, Ill think about ordering two new head units, so that I can clean one and have it ready for when the other one fails. I really hate taking things apart though, its one of my pet hates. Especially when I don't understand why I didn't have the same problem before. Thanks for the feedback though.

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Teflon could have too small inner diameter, providing a too large footprint for the

upwards hydraulic pressure, or spring is somehow too soft.

Here is a dirty fix: Find spacers with an 8mm inner hole, put on top of teflon underspring to

increase pressure.

But you have to clean up everything first...

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Well a couple of cups of tea a pack of custard creams and 34 pulls later i think my nozzle is clean now, lol. I was getting depressed around 24 pulls because it appeared to be getting worse again, but alas around 31 it seemed to clear up completely, but the motor still clicked like crazy when i loaded it in, so not sure what the problem is there. Im gonna order a ton of new nozzles, PFTE couplers and probably a few metal coupler parts too just to be sure. I did have a few jams earlier when the printer was essentially burning the filament for like 6 hours straight, a couple of times, but i thought i cleared it, i guess not. I did not look closely enough, but who knows, if it really was the nozzle or the coupler or the feeder?

20150903_223119.thumb.jpg.17852a79f3ee7e28affcc0afb36c46c2.jpg

20150903_225723.thumb.jpg.11a818c91d9d2c1bc5da5f49a757250d.jpg

Will standard PLA be OK for this new 'spring', it doesn't seem that hot there? and I don't really want to buy a whole roll of harder material that will probably jam my printer anyway.

20150903_223119.thumb.jpg.17852a79f3ee7e28affcc0afb36c46c2.jpg

20150903_225723.thumb.jpg.11a818c91d9d2c1bc5da5f49a757250d.jpg

Edited by Guest

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Will standard PLA be OK for this new 'spring', it doesn't seem that hot there? and I don't really want to buy a whole roll of harder material that will probably jam my printer anyway.

 

I have not tried it. mine is printed in clear XT, Korneel is also using that.

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Ill clean everything up again and see what happens, but im thinking the PFTE coupler i got was faulty, seeing as ALL the problems started when i got it. and it was fine before. I hope this just does not make things even worse.

EDIT, I've decided that instead the nozzle was just very slightly blocked causing constant slow jams, so I've left the coupler in and have had no problems since.....i just make sure the nozzle is 100% clean before a print now, and would suggest everyone to do the same to prevent under-extrusion as this in my opinion is the main cause.

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