1 Topic by Hecot (edited by Hecot 2016-03-26 20:09:10)

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Topic: hotend question - will a messy tread will act as a thermal barrier?

I've build a new hotend for my printer from new parts, new heat block, new screw, new nozzle! All brand new and put together nice and clean!

I started some printing with PET a new filament that I haven't used before. I tied some temperatures and found that 195°C gives the best results. Then I tried different nozzle diameters and on one I had a leaky nozzle extruding some plastics thru the tread, so the thread gets a bit messed up! After two more long term prints I noticed that the extruder starts clocking at that temperature and I have to increase the temperature by 20°C to 215°C to get a nice flow.

http://soliforum.com/i/?6KAmzBG.jpg

Is it possible that the messy tread will act as a thermal barrier so I will need a higher temperature at the heat block to get the same temperature at the nozzle? Does someone experienced the same when start printing with a complete new hotend?

If a messy tread is the problem - should I try to clean the nozzle tread or stick with the higher temperature???

2 Reply by AZERATE

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Re: hotend question - will a messy tread will act as a thermal barrier?

It's a little hard to tell by the pic, but it looks like you are getting oozing from the bloack rather than the tip. This is not normal and needs to be disassembled and cleaned. With PET, the only thing that will dissolve it is heat. So disassemble us much as you can and hit it with a torch.
Oozing into the threads is cause by not heat tightening the hotend. Let's say the thermistor can handle say 280c. You would heat it to about 275c and tighten it while the metal is hot. During normal printing (no exotics like PC), you should never have to reach the max number used during this tightening, and it will prevent the oozing. You have to consider the back pressure trying to fit through the tiny nozzle.

Did you actually build the hotend yourself from scratch? If so, very impressive.

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3 Reply by Hecot (edited by Hecot 2016-03-26 21:14:50)

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Re: hotend question - will a messy tread will act as a thermal barrier?

@AZERATE: Thanks for your feedback - meanwhile the oozing is stopped and I've aready cleaned the nozzle and tread as much as I can, but there is still some small amount of PET left inside the tread.

Now I've noticed that I will now need higher temperatures +20°C to get the same print results. My thought was that the messy tread will not let all the heat pass to the nozzle ... does this sound reasonable to you? If the messy tread is the problem - should I try to clean the nozzle tread or stick with the higher temperature???

PS: To answer your question - it's a modified hotend, see this tread for more details: http://www.soliforum.com/topic/14386/mo … avinci-10/

4 Reply by AZERATE

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Re: hotend question - will a messy tread will act as a thermal barrier?

For optimal performance in the future, I would recommend cleaning it all.
PET uses the same temp as ABS, but a lower temp setting is not the cause of the oozing. If anything, the oozing would get worse with increased temps.

You need to clear the gunk out and reseat the nozzle with a heat tightening. I've had this happen before. If filament starts spurting out in any direction other than out the nozzle tip, your numbers will be off even over time.

Printit Mason and Printit Horizon printers
Multiple SD2s- Bulldog XL, E3D v5/v6/Lite6, Volcano, Hobb Goblin, Titan, .9 motor, Lawsy carriages, direct Y drive, fishing line...the list goes on
Filawinder and Filastruder #1870.....worth every penny!

5 Reply by Hecot

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Re: hotend question - will a messy tread will act as a thermal barrier?

Yes, I removed the nozzle and it became obvious as the plastic already burned to a black coal! I cleaned it with a brass brush and drilled the heat block with a M6 thread cutter. Now I'm back to the old tempertures!

http://soliforum.com/i/?AEVCPP3.png