Another clogged HE!
Posted by KillerDave
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Re: Another clogged HE! March 17, 2016 01:25AM |
I have another one that I forgot to mention in all the PLA problem threads.
When I started printing with the original setup and the old Jheads I was pretty much used to cleaning the entire hotend if the printer was not used for a few days.
To be quite honest: I thought it is normal that the stuff in the hotend forms a hard brown mess
Then I changed to my first ABS roll and it was like the whole world changed.
No more clogging, no hours of useless cleaning, just good prints (well now I would call them crap but I was happy at that time LOL ).
Going back to PLA started the old troubles again but after some reading here in the forum I realised that my temp might be too high.
This was confirmed through thin wall prints and bridging tests.
I now have a little textfile on my cumputer where I note all brands, colors, year and month of sale, and all my print settings.
I also make my rolls with a number corresponding to the line in the textfile.
But the main change was how I start with a new filament:
I start with the lowest temp that is recommended by the seller and if my notes show even lower temps I use this temp.
The first 20 or 30cm of filament is wasted for measurements, flow tests and simply pushed through once I am done - I never use the first three or four "rings" of a new roll for a serious print!
Next step is a little collection of small testobjects to test solid infill, walls and bridging.
The speed is referenced from my notes and experience, the multiplier checked with the solid infill and thin walls.
The temp is referenced after the other parameters are fine through the bridging test.
Sagging means temp is too high, failing to bond means temp is too low - there is a sweet spot of about 5 degrees for every filament at higher speeds, around 8-10° for slower speeds.
ABS, Nylon and other "complicated" filaments receive finetuning with a solid 10mm cube.
Only if the infill is perfect, the perimeters are fine and nothing can be seperated with a knife edge I am certain to have the correct settings.
Keep in mind though that changing room temperatures will affect all this, some filaments react worse than others here and a heated bed and enclosed printer certainly helps the beginner and pro with big prints.
For PLA I sometimes do another test, which I call the "resting test".
If I suspect during a print my temp might be getting too high for slower speeds I intentionally give the hotend a chance to make the PLA go bad.
With the normal print temp set I let the thing just idle for about 20 minutes.
Usually nothing should happen in this case, except that the hotend runs dry as the PLA will drip out over time.
But if the temp is too high you can hear some crackling noise after the worst dripping stopped - this is boiling PLA!
As side effect of this boiling is that the PLA dries out completely and starts to burn to a brownish mess.
Still, unless your nozzle is very fine and the temp is not too far out, all this brown goo will come out when you extrude a few cm of filament.
If you check this goo and find hard brown rubbish with an almost crystalline structure you know for sure a disaster could happen during the next print.
With high print speeds you will never have a problem during your prints as the (too) high temp is required to enable good layer bonding.
But is you do tests, some cleaning of the plate or so and leave the hotend on....
If you encounter totally clogged hotends with PLA this neat trick might safe you a few hours of cleaning time.
The following is only for really bad blockages that can't be cleared with a wire or normal methods.
You know what I mean if you already had multiple cleaning sessions in a row with increasing levels of frustration.
With a normal hotend you only have the heatbreak and nozzle that would clogg up - the cold end or teflon liner should never be a problem to clear / replace.
Take the heatbreak and nozzle and some old pointy nose pliers.
Go outside with them and grab your blow torch.
Start with the heatbreak and hold it with one end down so the goo can drip out.
Heat gently and observe!
Once the plastic starts to drip be careful with the heat and make sure all vital body parts are out of reach of the molten plastic!!
Once you can see through take a toothpick or similar to clean most of the remains so you get a clean looking hole.
Now heat again but with increased heat to burn off all remaining plastic inside - don't go overboard and let the heatbreak change the color!
Everything left in there should be black ash that can be fully removed with toothpick and cotton buds - if in doubt finnish off with a bit of metal polish on the bud.
The nozzle hold with the screw end down and have your cleaning wire at hand!
Heat until the plastic start to drip and try to force the nozzle free with the wire (or drill).
If no luck heat again and be a bit faster this time
No luck again means you had the temp too high during your print and the nozzle got blocked by already charred PLA.
Clean the inside as good as you can and then heat the nozzle fully to burn out the charred plastic.
If you have a brass nozzle you can go really high here if the case requires it - just have a glass of water at hand for the last step!
A badly blocked nozzle means you need to get the entire thing hot enough to fully burn the PLA to just ash.
Punch a long nail through a piece of timer or put it in a vice and rest the nozzle on there - easier than burning your hands on the hot pliers.
If you can darken the area or do it at night time.
This way you can see once the brass start to glow slightly red - at this point nothing but ash should be left in your nozzle.
Take the pliers and dump the nozlle into the water.
This step will do two things:
A) The brass is hardend again.
If any of the remaining stuff in the tiny hole is still there and hard it be be cracked off the surface from the temperature shock.
After a quick rub with some metal polish you shall enjoy a hotend in mint condition ready to print.
When I started printing with the original setup and the old Jheads I was pretty much used to cleaning the entire hotend if the printer was not used for a few days.
To be quite honest: I thought it is normal that the stuff in the hotend forms a hard brown mess
Then I changed to my first ABS roll and it was like the whole world changed.
No more clogging, no hours of useless cleaning, just good prints (well now I would call them crap but I was happy at that time LOL ).
Going back to PLA started the old troubles again but after some reading here in the forum I realised that my temp might be too high.
This was confirmed through thin wall prints and bridging tests.
I now have a little textfile on my cumputer where I note all brands, colors, year and month of sale, and all my print settings.
I also make my rolls with a number corresponding to the line in the textfile.
But the main change was how I start with a new filament:
I start with the lowest temp that is recommended by the seller and if my notes show even lower temps I use this temp.
The first 20 or 30cm of filament is wasted for measurements, flow tests and simply pushed through once I am done - I never use the first three or four "rings" of a new roll for a serious print!
Next step is a little collection of small testobjects to test solid infill, walls and bridging.
The speed is referenced from my notes and experience, the multiplier checked with the solid infill and thin walls.
The temp is referenced after the other parameters are fine through the bridging test.
Sagging means temp is too high, failing to bond means temp is too low - there is a sweet spot of about 5 degrees for every filament at higher speeds, around 8-10° for slower speeds.
ABS, Nylon and other "complicated" filaments receive finetuning with a solid 10mm cube.
Only if the infill is perfect, the perimeters are fine and nothing can be seperated with a knife edge I am certain to have the correct settings.
Keep in mind though that changing room temperatures will affect all this, some filaments react worse than others here and a heated bed and enclosed printer certainly helps the beginner and pro with big prints.
For PLA I sometimes do another test, which I call the "resting test".
If I suspect during a print my temp might be getting too high for slower speeds I intentionally give the hotend a chance to make the PLA go bad.
With the normal print temp set I let the thing just idle for about 20 minutes.
Usually nothing should happen in this case, except that the hotend runs dry as the PLA will drip out over time.
But if the temp is too high you can hear some crackling noise after the worst dripping stopped - this is boiling PLA!
As side effect of this boiling is that the PLA dries out completely and starts to burn to a brownish mess.
Still, unless your nozzle is very fine and the temp is not too far out, all this brown goo will come out when you extrude a few cm of filament.
If you check this goo and find hard brown rubbish with an almost crystalline structure you know for sure a disaster could happen during the next print.
With high print speeds you will never have a problem during your prints as the (too) high temp is required to enable good layer bonding.
But is you do tests, some cleaning of the plate or so and leave the hotend on....
If you encounter totally clogged hotends with PLA this neat trick might safe you a few hours of cleaning time.
The following is only for really bad blockages that can't be cleared with a wire or normal methods.
You know what I mean if you already had multiple cleaning sessions in a row with increasing levels of frustration.
With a normal hotend you only have the heatbreak and nozzle that would clogg up - the cold end or teflon liner should never be a problem to clear / replace.
Take the heatbreak and nozzle and some old pointy nose pliers.
Go outside with them and grab your blow torch.
Start with the heatbreak and hold it with one end down so the goo can drip out.
Heat gently and observe!
Once the plastic starts to drip be careful with the heat and make sure all vital body parts are out of reach of the molten plastic!!
Once you can see through take a toothpick or similar to clean most of the remains so you get a clean looking hole.
Now heat again but with increased heat to burn off all remaining plastic inside - don't go overboard and let the heatbreak change the color!
Everything left in there should be black ash that can be fully removed with toothpick and cotton buds - if in doubt finnish off with a bit of metal polish on the bud.
The nozzle hold with the screw end down and have your cleaning wire at hand!
Heat until the plastic start to drip and try to force the nozzle free with the wire (or drill).
If no luck heat again and be a bit faster this time
No luck again means you had the temp too high during your print and the nozzle got blocked by already charred PLA.
Clean the inside as good as you can and then heat the nozzle fully to burn out the charred plastic.
If you have a brass nozzle you can go really high here if the case requires it - just have a glass of water at hand for the last step!
A badly blocked nozzle means you need to get the entire thing hot enough to fully burn the PLA to just ash.
Punch a long nail through a piece of timer or put it in a vice and rest the nozzle on there - easier than burning your hands on the hot pliers.
If you can darken the area or do it at night time.
This way you can see once the brass start to glow slightly red - at this point nothing but ash should be left in your nozzle.
Take the pliers and dump the nozlle into the water.
This step will do two things:
A) The brass is hardend again.
If any of the remaining stuff in the tiny hole is still there and hard it be be cracked off the surface from the temperature shock.After a quick rub with some metal polish you shall enjoy a hotend in mint condition ready to print.
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