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Hello all makers. I’ve build a 3d printer, a, Graber i3 frame with a J head metal nozzle and a Bowden setup. Got my first prints in last December and things were general getting better with many changes and upgrades I’ve been making since. I even got some very nice detailed prints at 0.05 mm layer height. But nos it seems tobbe going backwards, its even dificult to havê food first Mayer adhesion and the nozzle oozes a lot getting full of burn ABS on the outside. Can some onde point me in what to look to solve this problemas?. I’ve just made a deep clean in the nozzle, inside and out and I notice that the PTFE LINER is just a bit shorter than the fit inside the m6 throat, is that OK? Thank you.

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Hi, one thing you can do is reduce by a very small factor the filament feed rate, print a small test pattern and adjust again if needed. If you use Slic3r (which I recommend btw), there is a setting called “extrusion factor” (or similar) which you can use for that.

On Slic3r, there are specific parameters for fighting ooze, such as retracting the filament between “jumps” of the nozzle. Here is some info about that.

Good luck!

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nozzles are a consumable item, the same goes for throats - our printers work pretty much 24/7 and we tend to swap them out once a week to maintain print quality - they cost so little that cleaning them just isn’t worth the effort.

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If you are burning the filament then you are giving too much heat. Reducing the temperature should solve both the extra filament ooze and the burning problem simultaneously. How is PLA print output?!

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Thank you for the sugestiona. I will try that as soon as soon as I reassemble the hotend. I just feel that in my mods I must have ruined something that was working well. My suspects go to something around the hotend … Maybe temperatura … Maybe extruder … Retraction … And about oozing, my nozzle tende to drop ABS before the prints starts, line if it had pressure inside…

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I never tried prints PLA , I hear it is an easyer plástico to prints with.

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So if I read correctly the issues you have are: first layer adhesion and oozing. And you have a query on the PTFE liner.

1. First layer adhesion is more to do with the bed and Z minimum rather than the nozzle. The extrusion width for the first layer is also a factor. Forst - check your bed level and your Z-min. Readjusting these will have the greatest effect. Of course also the bed surface treatment is important. Also your slicer may have some settings for the first layer such as slowing speed by a % or increasing the extrusion width for the first layer or even increasing the height of the first layer - all these can help with first layer adhesion in different circumstances.

2. Oozing - two things can reduce oozing - the pressure in the melt-zone in the nozzle and the temperature. If the pressure is too high then you get more oozing out. To reduce the pressure then increase the retraction distance in your slicer. Because you have a bowden, then your retraction distance will be much more than a direct drive system. Do some tests - try 2mm and increase to see the effect. Secondly temperature - a higher temp increases the viscosity of the material and oozing is easier. Try reducing the temperature a little to see if you get less oozing. In balancing retraction and temperature and doing some tests at different levels, then you will come towards good settings for different filaments.

3. PTFE liner - the PTFE liner in the J-head stops before it gets to the nozzle. This is important because the PTFE needs to stay away from the hot zone (it breaks down high temps). There isn’t a heatbreak in a J-head - just a gap. In the e3d hotends there is a heatbreak.

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I just saw that you are using ABS. I generally print ABS with a raft - it helps with adhesion and also reduces warping.

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i used j-head also ,same as you .the ptf-liner has to keep his orginal length, when it is short it will move by the retraction ,

then the molten plastic flows every where inside and burns ,

so , replace new ptf-liner , and clean the hole shit, then all is orginal again.

this happens when you heat the hotend to much , the ptf-liner will shrink a bit and that’s what happend by your j-head,

thats why i left the j-haed .and got e3d-v6 full-metall orginal and copy’s i have they work great .

Less work for cleaning same configuration as j-haed .

I use the j-head only for pla-flex with no problems ,due the low temps it needs.

good printing!

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The oozing problem might be because of your software settings. Use cura software to print. It’s got awesome default settings for starters.

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Hello. Thank you for all sugestions. I just reassembled my hotend and make some test prints last night and I’m getting confident again. I arranged removed the play that the PTFE liner had inside the metalic throat and for now its working good, and I already ordered a fully metalic thoat (without PTFE liner).

I got back to Cura slicer, after trying Slic3r and Simplify3D. It is a simple slicer (less setups to tweak) but gives excellent results, at least for me. Only down side is about bridging, I miss some tweaking for that, but one can achieve some nice results playing with the plugin Tweak at Z.

I guess that if I config enough Skirt lines the nozzle will prime to achieve a steady and uniform flow and that will help in the first layer adhesion.

I’m still figuring out what should be the correct temperature for ABS. I was convinced that 240º was fine, but the smell is stronger and bridging gets worst. With 235º bridging gets better but as I lower the temperature, I get weaker parts.

Thanks again and great prints to you!

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Glad that it’s working for you. The temperature reading is based on the thermistor placement. Since you have assembled your own version of the hotend, set your temperature after trying different temperatures varying from 220 in increments of 5. Then based on the output set the temperature in the software.