Is this teflon coupler gone?

[personal-drones 44]

Yesterday I successfully printed out the first half of a vase:

When I launched the print for the second half (after a couple of hours from the end of the first part, during which the machine was shut down), I immediately noticed that the filament was having an hard time at coming out. Nearly no filament was coming out. Mind that the first half of the vase had printed perfectly up to the very top.

So I performed a first 2x atomic pull, the outcome was kind of clean, no particular residues or carbonized stuff. Material is white colorfabb PLA. Tried to print again, and again it did not look good.

So I took out entirely the filament from the bowden, with the idea that some chewing might have occurred on the feeding point, and that I would cut out all the last portion of the filament that had "seen" the feeder, and start over.

Did another couple of atomic pulls to be on the safe side.

Re-levelled the bed, just in case.

So I started over, and although I could see some signs of underextrusion at the beginning, then it looked good enough. I let it go and went to sleep.

This morning, I go in the room and the nozzle was going around, a couple of cm above the first part of the print, extruding nothing. So all the tinkering of the day before had been kind of useless. I definitely was having some problem.

I decided, from the shape of the atomic pulls, that maybe I had to replace the teflon coupler. Luckily I had bought one spare a while ago, so I could try that.

I replaced the piece, and now apparently the printer is like new, no signs of underextrusion in the last hour or so of printing the second half of the vase. I hope the problem is solved for now.

I would like to ask you guys, that have surely seen some teflon couplers gone bad already, if from the photos below it is safe to conclude that indeed the teflon coupler might have been the problem.

It still looks circular to me, not oval.

However it is like if a very tiny circle of carbonized teflon, at the meeting point with the hot end, has "extruded" outside. Not in a regular way. I think this shows in the pictures. Can this be the cause of my problems?

Maybe I can add here how much I am appreciating these forums. Without those, and the same problems I am experiencing, I would be totally in the dark. Conversely, with all the information available from the experience of others, I feel I am at least partially in control, and can also ask for advice and help. This is an amazing "collateral" value of my Ultimaker printer. I really want to stick to it and do all I can to have it run at best, as I believe it is a solid and special machine. Just love it, even if it is (still) not perfect apparently

EDIT here's another one:

 

[Anders Olsson 136]

Whether you can save that teflon coupler or not depends on if it is deformed on the inside or not.

If it is just that burnt edge, you can probably get it back in working condition with a 3.3 mm drill bit.

Under certain conditions the teflon couplers deform though, which makes them unusable (for PLA at least).

Check korneels photo of how a badly deformed coupler looks when cut in half and try to determine if yours looks the same way inside: http://umforum.ultimaker.com/index.php?/gallery/image/11465-wp-20150107-014/

 

[personal-drones 44]

Whether you can save that teflon coupler or not depends on if it is deformed on the inside or not.

If it is just that burnt edge, you can probably get it back in working condition with a 3.3 mm drill bit.

Under certain conditions the teflon couplers deform though, which makes them unusable (for PLA at least).

Check korneels photo of how a badly deformed coupler looks when cut in half and try to determine if yours looks the same way inside: http://umforum.ultimaker.com/index.php?/gallery/image/11465-wp-20150107-014/

 

Yes Anders, this is exactly how mine looks if look closely inside. So I guess it is gone.

Do you think this this enough to justify the problems I described?

The currently ongoing print with the new teflon is still looking excellent after a few more hours, I guess this was it. I am surprised that the original teflon lasted so little, I have owned this printer for nearly exactly one month now. When the print is over I will look at the exact number of hours and post it here, for the record. Exclusively printed in PLA so far, never over 230°C.

Thanks!

 

[swordriff 119]

Ciao!

At what temp do you do Atomic Pulls?

I try to stay below 235. The Teflon decomposes quickly over 230.

It is really strange, how for some the Teflon piece lasts "for ever", and for others not.

Maybe, just maybe there is a connection with how far down the steinless steel coupler ( the one with the radial holes in it, holding the teflon piece) is screwed down onto the brass, changing the pressure point between the Teflon and the hot end top end.

Your Teflon looks like it has been hot under pressure.

Another tip: The oldies here do not overtighten the 4 print-head-assembly screws, the long vertical ones. just tighten using fingers not too hard. Make sure the sliders still fit correctly.

Play with it. I would still try to use the teflon piece, using a "reaper" to clean the edge of the hole. Cut as little as you can.

IF YOU touch the stainless steel coupler (with the radial holes), remember to do a bed alignment so you will not suffer a head crash, better not.

[personal-drones 44]

Swordiff thank you! So many things to look for, will go over all of them as soon as my current print is finished.

I do the atomic pulls at 260/90, as indicated in the official manual, but will now rethink that.

Thanks again, great feedback from you guys.

 

[swordriff 119]

I guess Atomic is sometimes necessary at 260.

I try to avoid that!

Take care!

[tinydancer 0]

I had the same underextrusion issue and replacing the teflon coupler did the trick. Mine didn't look as bad as yours but I couldn't salvage it anyway as it was stuck and I pulled it out with pliers and it completely deformed the shape.

Btw, I do my PLA atomic pulls at 210 and I've never had a problem.

 

[personal-drones 44]

I had the same underextrusion issue and replacing the teflon coupler did the trick.

Btw, I do my PLA atomic pulls at 210 and I've never had a problem.

 

Thanks TD. Will definitely rethink my pulls protocol

 

[pm_dude 27]

It's true about those thumb-screws. Some UM2 like mine had been assembled and tighten with pliers and so much pressure was applied that the black frame of the print head was cracked in many places.

 

[personal-drones 44]

As an happy ending, here's the final vase, glued:

And these are my usage stats after this 20h or so print (I replaced the teflon just before it):

So it looks like I had to replace the teflon spacer after about 340 hours of use with PLA exclusively, at 210-230°C.

Just for the record.

 

[tinydancer 0]

Glad it's working for you again PD. Seems like results will vary, I got around 500 on mine before it needed replacement.

The vase looks great!

 

[personal-drones 44]

Thank you TD, yes I also love this vase. This print is 30cm tall.

Scaled up one of those: http://www.thingiverse.com/thing:481259

1.5x, cut in half with netfabb basic.

Cheers!

 

Glad it's working for you again PD. Seems like results will vary, I got around 500 on mine before it needed replacement.

The vase looks great!

 

[jcoutts 5]

Just as a note, I had a teflon piece that looked exactly like yours, and I actually ended up using a deburing tool to ever so slightly cut off that burnt ring. Then I reassembled the extrude head and now it is working fine.

Don't know if thats worth a shot or if you just went for another one.

 

[personal-drones 44]

Well I went for a new one now. I must say it is so much hassle to deal with, or just fear underextrusion all the time, that I am just happy to replace it if this solves the problems for good for the next 340 hours of print

 

Just as a note, I had a teflon piece that looked exactly like yours, and I actually ended up using a deburing tool to ever so slightly cut off that burnt ring. Then I reassembled the extrude head and now it is working fine.

Don't know if thats worth a shot or if you just went for another one.