fredag 12. juni 2015

How I broke a brand new E3D Lite6

Update 2015.06.23, E3D going above and beyond.

I messed up when trying to extract the nozzle, and the extractor broke off inside the block, making it near impossible to fix.
Driving out a drill bit with a drill bit
turned out to be difficult, as the softer
metal in the block gave away.

The issue with the nozzle breaking was due to me not following the nozzle swap procedure, which has to be done at 245C... As well as the liner compressing thus forming a plug.
I always ment to pay for new parts, but E3D actually gave me store credit to buy a new one(!) which was far beyond what I would have expected.

From E3D/Sanjay email: "The reasoning for me providing a replacement is that I think there could be an issue with the tube/lining coupling, and that there may be an issue on the internal bore which prevented you from inserting your liner fully. I am absolutely certain that the leaking you experienced is a result of the nozzle tightening procedure not quite being performed properly. You should be able to solve any leaking issues with a quick nip up and tighten of the nozzle when hot."

I'll report back with a new modified wades and my experiences with a more carefully assembled lite6.

Original post:

I just finished building a Mendel 90 sturdy for the school I work at, and started printing today together with my students. Everything worked pretty well and we did a few various prints, they really enjoyed this one. 

The extruder is the standard 3mm wades that comes with the Mendel 90 source, printed in ABS. I drilled out the filament path to fit the PTFE liner and just used it stock like that.

I had some issues dialling in the extruder settings though, and had to increase the extrusion multiplier to 1.1-1.2 to get acceptable solid prints, but there was still a lot of stringing. After a while I chose to remove the extruder idler to have a look inside, and I saw this.

The bottom PTFE liner should be flush with the plastic,
but it have moved quite a lot upwards.

The collet looks like to be in the right position.

I removed a good chunk of plastic to avoid moving the collet when inserting the hotend.

Teeth looks fine, and have not clogged.
Since this is the 3mm version, and the filament path hole is not moved, the idler does have to be tightened almost all the way, and the bearing does bend the filament slightly. But since there are no clogs, and it was easy to change out the filament, I reasoned it would be fine.

The nozzle is positioned correctly according to the assembly instructions.

I had to heat the hotend to 120C to unscrew the nozzle.
This is what it looked like.

The filament is pulled out and clearly shows the
PTFE liner was not completely flush with the nozzle.

Slight leaking from the top of the heat block.
After looking at it a bit and reinserting the PTFE liner a few times, I felt there was a tiny edge at the bottom of the heat sink, and you need to use quite some force to push the liner past it. I figured I rather push the liner through the heat sink and the heat block and then screw the nozzle into the heat block moving the liner upwards to make sure there is a tight fit.
Update: This was a terrible idea, the liner got compressed and probably had a lot to do with the nozzle breaking.

I started screwing in the nozzle with the liner like this. 

It was quite hard to screw the nozzle back on, possibly due to the plastic left in the threads, so I heated the hotend to 120C to make it soft and started out. Then...
Seems like I need a new nozzle, liner and heat block..

Any ideas to what could have caused this? I followed the instructions very carefully. The collet was properly secured, I could not move the PTFE liner up and down by hand. Thermistor settings were correct. I ran a M303 to ensure the temperature didn't overshoot, before heating to 245C and tightening the nozzle.

My guess is I only got the PTFE liner down to the small lip inside the heat sink opening, and there was a gap allowing the PTFE liner to move.

I'm in contact with E3D support already (they answered very fast), and wrote this post to better show my problem to them and to help others avoid the same mistake.

Thanks for reading!

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