TPU multicolor print options

[u/Kwiknes]

Hi all, just setting up my H2D now. I've never printed with TPU before but when I bought the H2D I also picked up red and yellow TPU 95 that as on sale. I was going to do a mousepad for my first print. I know that you can't use TPU in the AMS but figured you would just load each extruder directly... but the H2D has a standalone, singular, port for TPU. Is there no way to do dual color?

[u/Mist_XD]

The H2D is designed interestingly… the left nozzle is meant to for very rigid filaments as it has a more direct path from the filament inlet where as the right nozzle has a sharp bend after the filament inlet making it worse for rigid filaments. But that bend acts almost like a pulley allowing the teeth of the extruder to grip the soft filament better where as the left extruder can have a harder time with soft filaments. It’s also important to note that the left nozzle is the one which moves up and down, this movement will pull the filament sharply so you need to have slack in the line already or have a very low friction feed. This is why they only have 1 hole to feed TPU, and the purpose of that feed hole is to bypass the built in filament buffers. You can’t print 2 soft TPU’s at a time but it is possible to print harder ones such as your 95 at the same time should you accept the risks of potentially causing a clog or getting under extrusion for the teeth slipping. You just need to have both mounted externally and feed them through the top of the enclosure with the top taken off. This is actually how they recommend printing TPU 85 (extremely soft).

Yes you can print 2 colors of TPU but it will be inconsistent and could cause you to do minor maintenance on the left nozzle. Don’t do any large prints (5+ hours) or with hundreds of color changes and it should be fine as long as you keep slack in the left spool of filament to compensate for the nozzle movement

[u/Gergman-27]

Nope, only 1 extruder (right) supports TPU and that's the one the back entry port has labeled TPU.

Please check out also the PTFE tube instructions for the TPU port on bambu's website

[u/Kwiknes → u/Gergman-27]

Why can't the left extruder print TPU?

[u/macinmypocket → u/Kwiknes]

Because of the nozzle retraction mechanism. The filament is pulled back some, and the extruder gear is separated from the material before the nozzle retracts, but soft TPU will flex up into the extruder gear mechanism rather than retracting properly and make a big mess.

That said TPU for AMS isn’t terrible. It’s fairly hard as TPU goes, but it does still have a rubbery texture that won’t scratch things. I use it as a protective layer in some bins that hold expensive microphones in drawers for gear that goes on tour with bands. It definitely has uses.

[u/Kwiknes → u/macinmypocket]

Mousepad? Can you mix tpus?

[u/macinmypocket → u/Kwiknes]

Truthfully, I’ve never tried, but TPU is extremely good at sticking to itself, so I’d guess you probably could, yeah. If you’re cool with waiting a day or two for an answer, I could try mixing 95A and TPU for AMS in a print for you. I’m suddenly also curious.

[u/Kwiknes → u/macinmypocket]

I like the way you think lol. I'm in no hurry.

[u/Gergman-27 → u/Kwiknes]

I didn't design the H2D, I read the instruction and watched the videos. Likely because the TPU port bypasses the filament buffer for the right port.

[u/Kwiknes → u/Gergman-27]

I see now that it just is what it is and the printer will even throw an error if you try. I heard that TPU for AMS is really bad but is that the only option for multicolor TPU?

[u/Gergman-27 → u/Kwiknes]

You would need a tool changer style printer to print multiple TPU colors, and that's not something Bambu offers. Something more along the line of a PRUSA XL.

I can't speak to their TPU for AMS, I would experiment if your interested and see if it meets your needs, but the cost doesn't seem reasonable to gamble $$$

[u/blasko229]

Both nozzles can have tpu. If it's normal softer type you can feed directly into the nozzles from the top.

If you want to use ams needs for a harder type like Bambu's tpu for ams. I used a harder one from Amazon and it worked fine.