changing nozzle - will not screw all the way back in.

[peetersm 124]

I have an UM2+ and am wondering what I need to do to get the nozzle turning smooth and going all the way back into the olsson block again. I'm on my 3rd swap and it's progressively required more force to screw the new nozzle into the block. Trying to put the 0.4 nozzle in, before it was right up next to the fan shroud. Now it's stopped turning easily with 2mm still to go it's so tight I fear I will break something.

here's what I've done so far.......

It's brand new and I am following the official looking directions here:

https://ultimaker.com/en/resources/18805-changing-nozzles

Which says to do an atomic pull , leave it at 90C, remove nozzle, install nozzle, all at 90C the whole time.

1st swap - 0.4 to 0.8 - the atomic pull was great, the nozzle was kinda hard to remove with the tiny box wrench supplied with the printer, but it came out with some groaning sounds. (I don't know how much force was needed since I don't have a torque wrench, but it seemed good and snug) The 0.8 nozzle went in really easy for about 3 turns then became very stiff but I was able to turn it until it stopped right below the fan shroud. (all steps done at 90C)

2nd swap - 0.8 to 0.25 - the atomic pull was great - again removing and installing nozzle was tight, to took more force to seat the 0.25 nozzle. everything done at 90C

3rd swap - 0.25 to 0.4 - the atomic pull was great - removing was harder than before with the groaning metal. now I can not get the 0.4 nozzle to go all the way in. Still first 3 or so turns are fine, but then it gets very tight.

then I cam across these official looking directions:

https://ultimaker.com/en/resources/17869-swapping-nozzles

Which says to do the swap at the last printing temp

" If the temperature has dropped after removing the nozzle previously, go to “Maintenance” > “Advanced” > “Heat-up Nozzle” again and set it to the printing temperature of the last used filament (e.g. 210 for PLA, 250 for ABS). If the block is not at the required temperature when the nozzle is swapped, leftover plastic will prevent the nozzle from being tightened properly."

SO

I tried heating up the nozzle to 220C which was the last PLA temp I was printing at. the nozzle did not go in any easier. Also while it was hot I swabbed the inside threads gently with some tissue to see if any PLA was globing around in there and it came out clean.

then I tried cold....Nope.

so what temp do you use and what should I do? Should I get a torque wrench to make sure I don't break it?

[fbrc8-erin 274]

I usually use the 3D printed torque wrench when changing out the nozzle tips.

Is there any filament getting caught between the threads on the nozzle tips or on your Olsson block?

[xeno 108]

If you have been printing material that needs higher temps (250), you need to warm the hotend more, otherwise the material inside is not soft enough to screw the nozzle back in.

I always leave the hotend at 220C when changing, never had problems

[peetersm 124]

thanks for the tips and info.

I'm not able to detect any filament gumming up the threads. if there is filament in there do you just ignore it and keep making the nozzle hotter when changing? or is there a cleaning method that works for you?

I did try at 220C and that was not any better. I can try hotting but I have only been printing in PLA, so 220C should be hot enough.

I may go buy a real torque wrench after finding and reading about the 3D printed one...you need to buy a 7mm socket and if printed in pla it can get melty when the heat transfers from the nozzle to socket to pla.

[neotko 1,417]

To clean the inside what I do it's take out the nozzle, heat to 150-160c and manually push pla around the inside threads. Then cooldown to 80-90 and reverse atomic. Repeat until fully clean. The threads take 2-3 reverse atomics to get them fully clean.

[Remy 13]

thanks for the tips and info.

I'm not able to detect any filament gumming up the threads. if there is filament in there do you just ignore it and keep making the nozzle hotter when changing? or is there a cleaning method that works for you?

I did try at 220C and that was not any better. I can try hotting but I have only been printing in PLA, so 220C should be hot enough.

I may go buy a real torque wrench after finding and reading about the 3D printed one...you need to buy a 7mm socket and if printed in pla it can get melty when the heat transfers from the nozzle to socket to pla.

 

The socket should have been included with the Olsson kit, unless they're not coming with the kits anymore. I printed the wrench attachment in CPE to prevent any melt from happening when the socket heats up. It's worked really well so far, though it's not as permanent of a solution as a metal wrench. If you haven't been using any torque wrench to tighten the nozzle, you're probably getting some filament leakage in the threads, which might be causing the issue. I don't think you can get it as tight as it needs to be with hand strength only.

If it's not leakage, I have found that some of the threads on the Olsson blocks and nozzles need to be "worn in" when new from the factory. Small artifacts and burrs leftover from the manufacturing process can remain and cause binding when screwed in the first time. I usually screw the nozzle in most of the way, then back it out and rescrew it in if it requires more force than usual. Then after changing out the second time they seem to be better. Of course, you don't want to force it too much otherwise the nozzle could get stuck, snap, or strip the existing threads in the block.

I haven't done any reverse atomic pulls. The regular Atomic pull should work fine for cleaning out the nozzle inside, and heating the block without the nozzle installed should cause excess material to melt away from the threads there.

[neotko 1,417]

I don't mean to do atomic with the filament in. You do an atomic, take out the nozzle, and then you heat the hotend without the nozzle and insert filament where the nozzle should be, then you reverse atomic to clean the threads if they had blackgoo from a leak.

[Remy 13]

I don't mean to do atomic with the filament in. You do an atomic, take out the nozzle, and then you heat the hotend without the nozzle and insert filament where the nozzle should be, then you reverse atomic to clean the threads if they had blackgoo from a leak.

 

I see I've never seen anyone suggest this before, but it's a good idea - should work the same way as a regular Atomic pull does on the inside of the nozzle. I don't think it's usually necessary but could be a backup plan if the threads get gunked up real bad.

[peetersm 124]

@neotko I will try the reverse atomic. Do you fill the nozzle hole completely with PLA or do you only do one side at a time?

@Remy They are not shipping the socket any more, they are including a really cheap open box wrench. I'm worried I might have something more that filament gumming it up since it came out pretty hard the 1st time too.

[neotko 1,417]

I just put some inside where's needed. Use a phone camera to check it.

I used this method because I had 3-7 leaks while learning to assemble the hotend, so I had to improvise to be sure I was able to see the next leak if it happen.

Edited June 30, 2016 by Guest

[Remy 13]

 

@peetersm That's a shame :OThe old sockets were incredibly useful. I think using a socket wrench to attain right amount of torque will probably go a long way towards resolving material leaks and seepage. For the time being maybe try what @neotko suggested about the reverse Atomic pull.

Edited June 30, 2016 by Guest

[peetersm 124]

update-

i did the reverse atomic method and got the nozzle very clean. see photos. i put some tape on the fan shroud so i could keep the directions clear. and used a webcam with a cheap magnifier lens taped to it to get these shots.

But the nozzle still seemed very tight.

I was not able to find a source for a torque wrench that would measure 1.5 - 2 Nm. But I have an UMO+ so I printed the one Anders made. This allowed me to not be too worry about breaking the printer since it still took a lot of force to screw the nozzle in. The wrench slipped a few times before the nozzle was seated, but I would pause and turn it again and it would turn the nozzle a bit more...anyway long story short, I got the nozzle installed again and am very happy.

I would just say that anyone getting an UM with the Olsson block should print that wrench before ever changing the nozzle and buy a 7mm socket. The tiny wrench provided with the kit now is very difficult to use and the nozzle fits SOOO tight that you may not be able to put the nozzle back in with the wrench provided.

Thanks for all the great help everyone!