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PTFE tube/heat break/heatsink  

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Lize
 Lize
(@lize)
Estimable Member
PTFE tube/heat break/heatsink

After a time away from 3D printing I'm back!  I had a clog and I couldn't readily get it flowing, literally nothing would come out, couldn't do a cold pull, couldn't push it through and the filament broke off flush at the top of the PTFE - and then various events in life got in the way.

I've just disassembled the heat break (with sink in situ) from the heat block and taken the nozzle out.  The PTFE tube was really jammed and it was only after a fair bit of trying that it would come out but only by a bit and I couldn't get it out any further.  It pushed back in though and I think possibly a bit further than before although it doesn't look much different at the idler.

Before this terminal jam I had noticed that ASA had minor flow issues and looked a bit blobby although the prints were still useable.  I can't really remember what happened before the last jam, I think I did have a jam and did a cold pull and I'm wondering if I dislodged the PTFE tube a fraction perhaps.

Anyway I've managed to extrude the stuck ASA and run a fair amount of cleaning filament through, just going to have my dinner and then will try some PLA calibration squares so fingers crossed.

So my question is how do I know if the PTFE tube is at the bottom against the heartbreak or if there is still ASA in there, the cleaning filament ran clear after a few extrusions using load function.  Shall I just see if it jams again?  I didn't take the heatsink off the heat break as I haven't any thermal paste, should I order some in anticipation?

Thanks

Posted : 09/07/2021 7:26 pm
Diem
 Diem
(@diem)
Noble Member
RE: PTFE tube/heat break/heatsink

So my question is how do I know if the PTFE tube is at the bottom against the heartbreak or if there is still ASA in there

A cold pull should fetch out any residue.

Cheerio,

Posted : 09/07/2021 8:19 pm
Lize liked
Lize
 Lize
(@lize)
Estimable Member
Topic starter answered:
RE: PTFE tube/heat break/heatsink

So, after live Z a few PLA prints were fine.  I then did one with ASA and the problem re-emerged.  It printed OK but struggles to unload ASA, I now remember this was what was happening before the complete clog.  So I'm wondering why ASA is problematic to unload and PLA and PETG aren't.

To get it unloaded I had the temperature high and pulled whilst unloading and had stupidly failed to unscrew the idler door so you'll see the gear marks in the filament.

I've just found a couple of orange old cold pulls in the scrap box and also in the photo is the ASA black one from the unload.  Not sure if there is a problem that can be spotted with the orange ones but looking at the black one I think I have introduced more problems than before!

Am I right in thinking the PTFE tube isn't against the heartbreak (where its pulled either the previous grey PLA or cleaning filament out)  and I'm not sure the nozzle has a gap as well although its not oozing at the heater block?  I'm thinking I need to take it apart again and change the PTFE tube and make a better attempt at fitting it and the nozzle back together.

 

Posted : 11/07/2021 2:39 am
Diem
 Diem
(@diem)
Noble Member
RE: PTFE tube/heat break/heatsink

@lize

It's certainly a suspicious shape.  I've never cold-pulled ASA so I'm not sure how much stretching to expect.

If you've been struggling to pull the filament and using odd tools to grip it you may well have damaged the PTFE tube so changing it makes sense in any case.

For reassurance you could contact Prusa Support; show them the picture, and let them take you through the checks:  Log into your Eshop account, navigate to support and live chat is at bottom right in most browsers. If not you may need to disable your ad-blocker temporarily.

Cheerio,

 

Posted : 12/07/2021 4:37 pm
Lize liked
bobstro
(@bobstro)
Illustrious Member
RE: PTFE tube/heat break/heatsink
Posted by: @lize

[...] Before this terminal jam I had noticed that ASA had minor flow issues and looked a bit blobby although the prints were still useable.  I can't really remember what happened before the last jam, I think I did have a jam and did a cold pull and I'm wondering if I dislodged the PTFE tube a fraction perhaps.

This sounds similar to an issue that caused many problems for some users a couple of years back. For some reason, Prusa doesn't use the collet clip on the V6 hotend assembly as shown in step 19 of the E3D V6 hotend assembly instructions. I recall a number of users printing or buying one to add. I have not had problems myself, but keeps notes on this "just in case".

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 12/07/2021 4:42 pm
Lize liked
Lize
 Lize
(@lize)
Estimable Member
Topic starter answered:
RE: PTFE tube/heat break/heatsink

Thanks for the replies, very helpful.

Being a little perplexed about why the PLA and PETG is fine and the Fillamentum ASA fails to unload every time I've just thought to check the box and recommended is 240-255 but the pre-set Slicer profile is at 265 so will do a cold pull and retry at a lower temp.  I'll make conscious note to check new filaments against profiles in the future rather than just rushing ahead in excitement!

I think I should clean it out and replace the PTFE tube.  I'm tempted to buy a new assembled hotend and  I can then carry on printing without fuss and then take my time making sure the current one is spotless and have it as a spare.

I will definitely add a collet clip assuming the printed housing part doesn't clash with it.  Once I'd disassembled even though I couldn't readily get the PTFE tube out pushing and pulling on the tube easily moved it and the collet together and there was slippage of the tube.  If it had moved up a fraction then it could certainly be a source of stuck filament and pulling more would exacerbate it.

My usual filament supplier doesn't do hotends but they do have some polypropylene I've been wanting to try on sale so every cloud has a silver lining 😀.

 

This post was modified 5 months ago by Lize
Posted : 12/07/2021 11:12 pm
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