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In-Situ Nozzle Cleaning

Posted: Sat Oct 26, 2013 12:11 am
by JuliaDee
I had a devil of a time today going from OEM black ABS to NinjaFlex. NinjaFlex doesn't like any back pressure at all, it needs a very clean nozzle or it won't feed. After withdrawing the OEM filament, I ran some 3rd-party ABS through at 260, then at 230, and the extrusion was curling like crazy - it was even coming out in two separate streams. :shock: I stuck a 0.4mm drill bit in from the bottom while the nozzle was hot and twirled it, still bad. I sanded the face of the nozzle by putting some foam-backed sandpaper on the bed and moving the extruder around on it. Still bad.

As I've mentioned elsewhere here, a critical part of the nozzle is the "middle chamber" just behind the 0.4mm orifice. This section doesn't flush itself out very well through extrusion, but its cleanliness is critical to smooth extrusion and low back-pressure. In the past I've cleaned it by removing and soaking the nozzle in solvent, then twizzling a 1/16" drill bit around in it, but nozzle removal is a pain.

So today I did something different. I pulled off the feed stepper (feed mechanism all looked fine) and set it on the bed with all the cables connected. I called for heat via the Extrude button. Once the extruder was hot, I pushed the butt of the 1/16" bit into the down tube to spooge out all the plastic in there, then I put the bit in a pin vise with the pointy end out. Using the pin vise, I was able to twirl the bit inside the "middle chamber" with the nozzle hot. I dipped the bit tip in acetone and repeated a few times, pulling out gunk and wiping the (hot!) drill bit tip in between.

Put it all back together, and... perfect, smooth, straight extrusion. Nozzle completely cleaned without removal. NinjaFlex working perfectly :)

julia

Re: In-Situ Nozzle Cleaning

Posted: Sat Oct 26, 2013 11:16 pm
by Bindw
Thanks for the tip JD. I hate removing the nozzle and then having to set the print bed height again. This usually happens just after I have got it just right after a few failed prints. Murphys law! I have thought about dipping the heated nozzle, while in situ on the print head assembly, in a little container of solvent placed on the print bed, but I do worry about fire, etc This seems like a better solution. I can see how I'm going to spend the rest of the day.....

Bin

Re: In-Situ Nozzle Cleaning

Posted: Mon Oct 28, 2013 10:24 pm
by wackojacko
I find after a long time you get a carbon build up inside the nozzle and acetone won't remove it. Using Julia's drill technique works.

Re: In-Situ Nozzle Cleaning

Posted: Fri Nov 01, 2013 10:35 am
by ftdesigns
JuliaDee wrote:I had a devil of a time today going from OEM black ABS to NinjaFlex. NinjaFlex doesn't like any back pressure at all, it needs a very clean nozzle or it won't feed.
So would you say then that the OEM ABS clogged up the middle tube too much for the Ninjaflex to extrude right?

Re: In-Situ Nozzle Cleaning

Posted: Fri Nov 01, 2013 1:40 pm
by JuliaDee
ftdesigns wrote:
JuliaDee wrote:I had a devil of a time today going from OEM black ABS to NinjaFlex. NinjaFlex doesn't like any back pressure at all, it needs a very clean nozzle or it won't feed.
So would you say then that the OEM ABS clogged up the middle tube too much for the Ninjaflex to extrude right?
It would probably be more fair to say that I hadn't cleaned that nozzle in months of printing with every filament under the sun and the OEM black proved to be the tipping point :)