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White dust on the inside of extruder assembly.  

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jacob.b15
(@jacob-b15)
Active Member
White dust on the inside of extruder assembly.

I noticed a popping sound when printing PETG that usually means wet filament. But while printing with a brand new package that had been delivered sealed, the issue continued. The issue also seemed to manifest in prints with inconsistent extrusion, and severe stringing. Supports printed particularly poorly. 

So I took the extruder apart, and found a dusting of this fine white dust. I don't know what it is, there is none of it anywhere else in my garage, and no where else on my printer except for around the extruder assembly. I have a feeling that some of the air from the blower fan is disturbing that white dust that surronds the thermistor wire, and blowing it all over the place, though I don't know how its getting into the coldend and/or hot end.

advice?

 

This topic was modified 3 years ago by jacob.b15
Posted : 09/05/2019 1:54 am
Chocki
(@chocki)
Prominent Member
RE: White dust on the inside of extruder assembly.

Are you sure it is not smoke!.

I recently had a meltdown (Well I was printing at 295 Deg C 🙂 ) and some of the PETG melted onto the heatblock and when I took the extruder apart, I too had what looked like white dust around the melted sections. I concluded it must be some sort of smoke deposits from the melting plastic. I notice your heater block is rather, ermm well baked over with molten plastic, could this be the cause?, is there an acrid smell present when printing?.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 09/05/2019 7:51 pm
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jacob.b15
(@jacob-b15)
Active Member
Topic starter answered:
RE: White dust on the inside of extruder assembly.

That seems entirely plausible. I'm at a loss on how to fix it though... The only thing I can remove from the heatblock while its not heated up is the screw that tightens the block around the heater cartridge. Everthing else, the set screw holding in the thermistor, the thermistor itself, and the cartridge, are melted in place with PETG. 

And yes it smells a little acrid, but nothing too crazy.

Posted : 10/05/2019 2:26 am
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(@)
Illustrious Member
RE: White dust on the inside of extruder assembly.

I'd guess residue from boiling or flaming plastic.  Looks like, IMHO, you need to replace the heater block and start using a silicone sock to prevent what I suspect is stringing from coating the heater block again.  

I've read about printers burning down houses, Prusa's were supposed to be less prone to such things, and why I bought one. Now I need to concentrate on making a clip to hold my sock on better. lol.

Posted : 10/05/2019 3:26 am
jacob.b15
(@jacob-b15)
Active Member
Topic starter answered:
RE: White dust on the inside of extruder assembly.

Aright, ill bite the bullet and get another heater block. sigh. I want a heater sock as well, but they I have had no luck getting them to stay on the block. In my experience theyjust slip off and wreck whatever is being printed. 

Posted : 10/05/2019 2:45 pm
Chocki
(@chocki)
Prominent Member
RE: White dust on the inside of extruder assembly.

Hmmm, I wonder if a Boron Nitride Aerosol lubricoat would work to prevent sticking.

Normal people believe that if it ain’t broke, don’t fix it. Engineers believe that if it ain’t broke, it doesn’t have enough features yet....
Posted : 10/05/2019 3:16 pm
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(@)
Illustrious Member
RE: White dust on the inside of extruder assembly.

Ya know, a non-silicone based thermal paste brushed on the surface might not be a bad idea;   A bit messy for servicing but it would prevent things from sticking.

Though, a silicone sock is simple, easy, and works well until the fall down - so use a small (30awg) bare copper wire wrap to hold it in place. Or even a short U-shaped piece of piano wire as a spring clip ... 

I think there is a business there if someone built and manufactured a clip that slips on and off and works reliably.  You'd think E3D would have something rather than depend on almost useless tabs on the sock.

Posted : 10/05/2019 6:55 pm
vintagepc
(@vintagepc)
RE: White dust on the inside of extruder assembly.
Posted by: ...

Ya know, a non-silicone based thermal paste brushed on the surface might not be a bad idea;   A bit messy for servicing but it would prevent things from sticking.

Though, a silicone sock is simple, easy, and works well until the fall down - so use a small (30awg) bare copper wire wrap to hold it in place. Or even a short U-shaped piece of piano wire as a spring clip ... 

I think there is a business there if someone built and manufactured a clip that slips on and off and works reliably.  You'd think E3D would have something rather than depend on almost useless tabs on the sock.

I mold my own that have a full lip around the top and stay in place without assistance, using high-temp RTV silicone. $7 for a tube that makes an awful lot more than $7 at E3D gets you.

 

This post was modified 3 years ago by vintagepc
Posted : 10/05/2019 7:00 pm
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