How to clean a MK3 hotend  

RE: How to clean a MK3 hotend

Yes, a cleaning filament will help with this. A cold-pull using a cleaning filament even better.

RE: How to clean a MK3 hotend

I didn't think a cold pull was possible with our configuration? Do you pull out the short piece of boden tube? Thanks Gene

RE: How to clean a MK3 hotend

Posted by: gene.u

I didn't think a cold pull was possible with our configuration? Do you pull out the short piece of boden tube? Thanks Gene

You can pull up through the extruder. Open the extruder door to remove tension before you do the actual pull. You can pull up through the PTFE tube without issue.

I'm still running the Mk3 (pre-S) configuration, but my notes here should still be helpful.

RE: How to clean a MK3 hotend

I've successfully done cold pulls (with eSUN Cleaner Filament, non affiliate link and same product as in bobstro's notes webpage) with both the MK3 and MK3S extruders. Open the Bondtech idler door for both. No problem with hanging up on the lower PTFE tube on both, nor the top PTFE tube on the MK3.

RE: How to clean a MK3 hotend

Thank you Gentlemen. I use the printer [I have the MK3s parts on the way] everyday and make a lot of parts for my CNC router and CO2 laser cutter. It [and Fusion 360]  has opened a new world to me in my dotage [I am 73].

RE: How to clean a MK3 hotend

Also, make sure the exterior of your hotend is clean. I just finished a 3.5 hr white PC print where I happened to have left some black PETG stuck to the nozzle. I actually noticed it an hour in, but figured it's only a little bit of cosmetic imperfection, it can't really hurt that much. A little bit of plastic stuck to the exterior of a nozzle (or stuck to the outside of a sock) will decide to fall or drip off at the worst possible time.

Of course, upon completion I wasn't happy with it and I'm now reprinting it anyway.

RE: How to clean a MK3 hotend

What do you use to clean the outside?

RE: How to clean a MK3 hotend

Posted by: joe.m14

What do you use to clean the outside?

A soft brass wire brush works, but be careful around the heater cartridge & thermistor wires.

RE: How to clean a MK3 hotend

Also, consider a silicone sock to avoid build-up of filament on the heater block. 

RE: How to clean a MK3 hotend

Posted by: joe.m14

What do you use to clean the outside?

These days I'm using an E3D Nozzle X together with a non-pro sock (the kind that doesn't cover the nozzle). The Nozzle X is plated and has a nonstick coating and cleans up easily with a paper towel while hot. One of the benefits of this particular nozzle.

For a standard brass nozzle, or if you weren't running a sock and your heater block is covered with stubborn baked-on goo, the soft brass wire brush that bobstro recommends is the way to go. Having to do this one time on a non-socked heater block was enough to convince me never to run without a sock again. I really think they ought to include a 3-pack with the printer.

RE: How to clean a MK3 hotend

I've found a strip of cardboard works better for coated nozzles than paper towels. Less lint and tearing, and can just trim it off when it gets messy.