What’s the best procedure to change a H2D nozzle from a high temp and abrasive filament (300C+ PET-CF or Nylon-CF ) to a low temp filament (PLA or even TPU)? Fortunately I haven’t had to take apart a H2D extender (yet) annd I’ll be happy to keep it that way lol. So I’m a little fuzzy on what’s in there, architecture wise, where the cutter cuts, where are the push gears etc., since I’m coming from my simpler Prusa MK3S’s. I’m envisioning the PLA to have to potential to either a) not be able to push out the HT filament if it’s not melted enough or b) the PLA failing to push and hamming if the nozzle is at the higher temps. Do I need to figure out how to do a cold pull? I’m currently feeding from external spools, no AMS currently connected.
I haven’t had any issues switching from PPA-CF to PLA. The cutter cuts right above the entry to the nozzle, the push gear is visible without the plate and is a stainless steel gear that rotates clockwise or counter-clockwise depending on which nozzle is in use.
I haven’t seen too many threads posted about the filament swap being an issue, sometimes there are clogs, but those are easily solved by popping off the hot-swappable hotends, heating them with a torch/heatgun, and pushing an allen key through the back to clear out any extra filament.
Be careful with your chamber temp though, the extruder gear might deform the PLA and cause a jam if it’s too warm. I’d say you should be fine just following the standard procedure.
Standard procedure? Just “unload”, edit filament type, then “load”?
Yep, it should guide you through all the purging steps as well.
In addition to what’s already been mentioned, you’ll need to wait for the chamber to cool down before loading any low-temperature filament. If you don’t, you’ll soon become familiar with maintenance procedures…
Thanks. What’s max temp for chamber to do PLA switch?
I wouldn’t go over 45C chamber temp with PLA
That largely depends on which PLA you’re using, but to be safe, always aim for a chamber temperature below 40 °C. At that level, you can assume the filament paths have also cooled sufficiently to prevent unwanted behavior.
Thanks. Usually, but not always, I’d be switching on a cold machine. But good to know if I was doing anything back to back.
I just did this last night and had an issue. I printed something in PA-CF and wanted to unload the filament and just put back in my PLA spool, but using the guided Load and Unload wouldn’t work for me. The PLA wouldn’t push the PA-CF out my guess is it became too soft from the high nozzle temp required to melt what was left of the PA-CF and it jammed up in the extruder. Had to completely disassemble it and cleaned out the jam.
Next time I will try to just unload the PA-CF and let it cut the filament, then take the nozzle out completely and manually remove what’s left in it before trying to send a lower temp filament through.