Kywoo Tycoon 3D - Impossible to print after using PETG

[mosdev38]

Hey Printers,

im new to this forum and hope you could help me
Im from germany and uses my 3D printer for boardgame and smarthome stuff.
It is my first 3d printer, its a Kywoo Tycoon 3D printer.

Before i used to print some halloween things with glowing PETG, everything was fine and i was able to print with good results PLA.
For PETG i increases the nozzle temperature from 205° up to 235° and the bed temperatur from 60° up to 80°.
The result was pretty nice, with the same settings in ultimaker i was able to print some skeletons, bats and spinders with a good and smooth surface.

After that i switched to PLA and noted that my z-offset no longer fits. So i first use the paper-method to roughly determine the distance. After that i printed some one layer squares to determine the exact distance.
I noticed that the extruder gear maked some clicking noice, and i stopped the print. The PLA no longer adhered to the bed and the nozzle was apparently clogged.

At first I thought the gear was broken because it is made of soft copper. As I couldn't find the gear separately, I ordered the dual extruder with two gears. After installing the dual gear...same clicking.
It seems as if too much PLA is being conveyed and the nozzle is clogged, resulting in a PLA jam.

The Printer:
https://www.kywoo3d.com/en-de/collec...oon-3d-printer

Extruder:
dual gear extruder.jpg
New 0.4 nozzle(s) installed

Test Prints:
level.jpg
Leveling test - 0.2mm thick

flow.jpg
Flow test - each wall 0.4mm thick after setting flow to 94% because my line with is 0.4mm

stringing.jpg
Strining test - some ticker strings on the inner sides

pla.jpg
PLA - PLA rest from the nozzle after clicking and PLA jam.

At first I thought it was the PLA, but after I changed it, it got much better. But with each layer, PLA seems to build up and it starts to click (gear no longer grips and no longer feeds PLA).
I can't print anything with the standard profile from Kywoo Tycoon for PLA, I created an Ultimaker profile from the Enders 3 V2, which was used to create the test prints.

Does anyone have a guess as to what the problem could be? Could my hotend be damaged so that it is not heating constantly?

[Bikeracer2020]

just suggestions.....

Check extruder teeth are clean and not filled with filament.
Do a cold pull to clear the nozzle of any old filament.
Replace nozze.

[mosdev38]

The teeth are free, every time it jams I have to pull the filament out completely and cut the nozzle free.
Then it retracts again without any problems and I can print the flow test and level test.
However, as soon as I want to print normal objects like the Benchy, the flow is blocked and the gears clack because it can push a filament in.

The extruder is new, so it is not worn. I had replaced it because of the clicking (does not draw in PLA) and cleaned it after each blockage.
I have now also replaced the Nozzel for the third time (0.4 mm).


Before I printed with PETG, everything ran without any problems, even on the default setting. The printer should also be able to print PLA out of the box.


I have just measured the nozzle with an infrared measuring device, the setting is 205° and I measure 200° on the outside.
When I pull out the filament after the extruder blocks, there is a 2.5mm lump at the tip, as you can see in the picture.

At first I thought it was because I was printing on a flexible substrate. However, the aluminum bed doesn't seem to be 100 percent flat, as I had a different image at the corners than in the middle when leveling.
Now I print on glass and the level test is identical everywhere.

[Bikeracer2020]

Does the extruder have a teflon tube between the exruder and the nozzle?

If it does is there any sign of degradation? Also check that the end is cut square and fits snugly up to the nozzle.

[mosdev38]

In fact, there was a Teflon hut in the hotend. It shrunk quite a bit at the end, about 0.3 mm to be exact. If you run your fingers along it, you can feel how it tapers off considerably. The sleeve is also totally clogged. Can I shorten the shrunken end and put it back into the hotend or does the sleeve have to be as long as the hotend? Can I purchase these sleeves separately or buy the component directly?How can this actually happen, I mean I have printed within the given framework conditions released by the manufacturer.Many thanks for your help!

[Bikeracer2020]

You can cut a piece of new teflon tube, make sure the cut is at 90 degrees at the end and a snug fit against the nozzle.

Ideally you need to convert to a bi-metal hotend with a heat break above the nozzle.in it .

I had the same problem with my Qidi standard hot end, the manufacturers state the hot end is capable of the temp you want, but on enquiring it is not suitable for prolonged use at the higher temp specfied.
I converted mine to an all metal hot end and have had no more problems with the hot end at 250/260 degrees.

There are loads of different bi-metal replacement parts on Amazon, you need to search for one that fits, some screw in with usually a 6mm or 7mm thread or are held in place with a grub screw.

[mosdev38]

I was lucky and the original upgrade kit for my printer was on offer.It's a complete hotend with bimetal and hardened nozzle. The kit allows printing up to 300 degrees.When it arrives, I will report whether everything is working as it should. Many thanks for your help, I would never have thought that the Teflon tube was the problem.

[Bikeracer2020]

Just be aware that a hardened steel nozzle might cause problems for normal plastic filament, if it does, just fit a normal brass nozzle.
I believe it's to do with the friction of the hardened steel, anyway just try it first.

Also if you change a nozzle, heat the heater block up by 10-20 degrees above your normal print temps and then tighten the nozzle home, same when removing a nozzle. This is to prevent leaking filament.