The right way to change nozzles

[singhm29]

I feel like im not doing this right at all.

Every time I find myself swapping the nozzles out the nozzle I take out ends up having hardened plastic so that I cant see clearly through it. To clear it I end up having to bathe it in weldon 4 which dissolves PLA but takes almost a day todo so.

My process for removing the nozzle consists of
Loosening the idler
Heating the nozzle up to 220
While it is heating slightly tugging on the filament until the heat fully allows it to release and pull out
Cool it down and unscrew nozzle

Is it normal to have solidified plastic in the hotend that will just ooze out when its reheated?

[CaptainObvious]

Why don't you just burn off the remaining plastic?
Don't even need to burn it all off, what I normally do is heat up the nozzle over a candle flame and use a toothpick to remove most of the gooey plastic from the inside.

[singhm29]

Why don't you just burn off the remaining plastic?
Don't even need to burn it all off, what I normally do is heat up the nozzle over a candle flame and use a toothpick to remove most of the gooey plastic from the inside.

Hmm that makes sense was just confused if maybe I was doing something wrong or if this was what most people experienced. Using a candle makes sense keeps both hands free.

[Roxy]

Well... It is hard to say what you should change. But everybody eventually gets a plugged nozzle. However, you seem to be talking about a common occurrence. You should try to not have the nozzles hot if they are not being used. That is the biggest thing you can do to keep the clogs from happening.

[singhm29]

Great tip and something I have forgotten to take care of at times.

Well... It is hard to say what you should change. But everybody eventually gets a plugged nozzle. However, you seem to be talking about a common occurrence. You should try to not have the nozzles hot if they are not being used. That is the biggest thing you can do to keep the clogs from happening.

[LambdaFF]

Printrbot support says to always have a metal wire brush at hand for hotend clogs. Not for the brush itself but becase the wire strands are thin and can be used to unclog the (hot ) nozzle. Works well for me, but use a pincer, wear gloves and glasses !

[singhm29]

Printrbot support says to always have a metal wire brush at hand for hotend clogs. Not for the brush itself but becase the wire strands are thin and can be used to unclog the (hot ) nozzle. Works well for me, but use a pincer, wear gloves and glasses !

Its not so much that my nozzle is clogging during a print or anything but I swear ive seen people heat up the nozzle pull the filament and it cleanly takes out whatever had gathered in the nozzle so it can be removed and a new nozzle can be put in and then the previous one can be reinserted at a later time without cleaning. Is that unrealistic?

[singhm29]

Just an update for anyone who wonders the same thing at some point.
Performing a cold pull is what I was looking to learn although these other tidbits of info have been helpful too! This leave me with a nozzle I can see completely through right after removal, no more soaking in weldon to loosen up the PLA so that its easier to remove
Now when I swap nozzles i dont have to spend a day soaking it in weldon to loosen up the PLA to unclog it everytime I want to switch. Just about a 10 minute procedure

Loosen idler
Heating the nozzle up to 220 (For PLA)
WHen at temperature push through a bit so you see it extrude (break this off so when you do pull the filament out you dont need to pull that mess through as well)
Cool down to 90 while holding onto the filament so more does not drip out
When at 90 Pull filament out!

Good sources of information on the actual procedure
<http://support.3dverkstan.se/article/10-the>
<http://bukobot.com/nozzle-cleaning>