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Hi everybody,

I was printing one of my first cube, and the extruder stopped feeding the hotend. I finally retracted and opened the hotend and the external of the two imbricated tube is broken (from top to bottom). What happend? Too much pressure?

Thanks,
VS

VerticalSpeed wrote:Hi everybody,

I was printing one of my first cube, and the extruder stopped feeding the hotend. I finally retracted and opened the hotend and the external of the two imbricated tube is broken (from top to bottom). What happend? Too much pressure?

Thanks,
VS

The outside PTFE tube is supposed to be split, to make it easier to insert the inner tube.

What was the temp you were using to print? If you detach the bowden tube from the extruder can you still feed filament? I had an issue early on in which I didn't have the feed rollers of the extruder properly adjusted. Mine were too loose which led to inconsistent filament feeds. To adjust the tension I kept tigtening the feed rollers till when I pinched the filament entering the feed rollers between my fingers I couldn't stop it. Also you should measure the filament after the roller to make sure you are not distorting the filament as that can affect your prints.

Hi,

Ok for the external tube so...
I'm heating my PLA at 185°c and 190°c for the first layer.
It's strange, because when I clean everything, I can feed the hotend by hand, and the extruder mechanism is not too loose, I can't stop the filament with the fingers. But when I start printing, the feeding stops, or there is very little plastic output.
Maybe my Z0 is too low?

In my many tries, I found a piece of plastic blocked in the rapid tube clip of the hot end.. Maybe the cold part of the hotend is too hot?

Btw, can somebody tell me the exacts dimentions of the inside tubes of the hotend? I want to check if they are not too short (I took off less than a milimeter to flaten it, but maybe it was a bad idea?)

VerticalSpeed wrote:Hi,

Ok for the external tube so...
I'm heating my PLA at 185°c and 190°c for the first layer.
It's strange, because when I clean everything, I can feed the hotend by hand, and the extruder mechanism is not too loose, I can't stop the filament with the fingers. But when I start printing, the feeding stops, or there is very little plastic output.
Maybe my Z0 is too low?

In my many tries, I found a piece of plastic blocked in the rapid tube clip of the hot end.. Maybe the cold part of the hotend is too hot?

Btw, can somebody tell me the exacts dimentions of the inside tubes of the hotend? I want to check if they are not too short (I took off less than a milimeter to flaten it, but maybe it was a bad idea?)

Do you have a fan on the PTFE part of the hotend, PLA will jam if you do not?

Hi,

No I don't have. Is this my problem?
I have a big fan pointed on the print, but I turn it on after the first layer (when it's working).

BR

VerticalSpeed wrote:Hi,

No I don't have. Is this my problem?
I have a big fan pointed on the print, but I turn it on after the first layer (when it's working).

BR

It's almost certainly the issue.
PLA goes through a phase where it's "rubbery" before it becomes a liquid what tends to happen is if the thermal break doesn't have sufficient temperature differential it mushrooms in side the PTFE increasing extrusion pressure to the point you can't extrude at all. I have 4 different hot ends here if you include the two different Steve's variants and they all require active cooling to reliably print PLA.
It doesn't take very much all you need to do is get some air to flow past the PEEK section of the hotend, I'm using a 25mm fan, 40mm fans are more broadly available in 12V's, but you'll need to print a fan mount.
You can get away with using an fan to the side (and I did for a long time), but you must run it continually and you must heat the hotend with the hotend in the airstream.
You may find that a "big fan" to the side produces too much cooling effect and you can't get the hotend to temperature because the heating element is Aluminum which is extremely conductive and doesn't have a lot of thermal mass. If this is the case find some thermal tape to use as insulation and wrap it around the bottom AL part of the hotend, I use silicon tape because it's what I had handy.

Thank you very much for your answer!
I'll try to orient my big fan on the top of the hotend to print a fan support ^^
While I have you, do you have the exacts dimentions of the inside teflon tubes?
The reprap wiki is down..

VerticalSpeed wrote:Thank you very much for your answer!
I'll try to orient my big fan on the top of the hotend to print a fan support ^^
While I have you, do you have the exacts dimentions of the inside teflon tubes?
The reprap wiki is down..

I don't know the lengths, I cut mine for the new nozzle, but I just did it based on the lengths fot the old nozzle and some measured nozzle dimensions. i.e. I just measured the amount to remove.
The diameters are 2mm ID 4mm OD, 4mm ID 6mm OD.
SeeMeCNC sells both, the inside tube is identical to the bowden tube, so at a push you can steal some from there, just don't steal too much.
I'd email Steve if you need the exact lengths, he usually responds very quickly.

Thanks master! I'll keep you informed in this thread..

Do you think I can connect the fan to the heating wires of the hot end?

You really don't want to do that. The resistors are constantly turning on and off to maintain temperature. Your fan would do the same. A direct connection between the power supply and fan is easiest. This way the fan will always be on no mater the temperature of the extruder. There are options to connect and drive fans from the Rambo board but they are more for cooling parts as you can change the fan parameters based on the print.

So I will connect the fan to a direct 12v supply.
Thanks

The problem is solved. Thank you