I have a design that I want part of to be ASA, and the other part TPU (the version safe for AMS). Bambu Studio warns of clogging from high and low temp filaments together. I am confused as to why this would be as each will run from its own nozzle (TPU in left, ASA in right)? Curious if others have done dual filament prints involving TPU and had any issues?
Thanks!
high chamber temperature.
You can create your custom ASA profile to disable the chamber heater and that should work, but you have to print slowly to reduce the warping force.
I think in the docs I saw that the TPU supports chamber temps of 25-45C. Think if I run on the higher end of that (40ish) it’ll be a happy medium of keep the ASA stable, but not over cooking the TPU? The TPU won’t be printing on the print bed, it will be more than a dozen layers up into the print.
Yes. You can definitely try it with TPU in right nozzle, ASA in left nozzle, theoretically very low risk.
Possibly ASA-CF could help to reduce warp.
If the ASA parts aren’t too large, I tend to print in low to mid 30c chamber temperatures in my X1C without issue. So as you noted, in the TSD you can print up to 45c in the chamber, so I think you should be okay with using that as a base chamber temp for ASA and TPU.
I’ll give it a try tomorrow - as soon as the TPU finishes its drying cycle. 
Because TPU and ASA have quite different optimal bed temperatures, running them together in a single print with a shared bed is problematic. If you set the bed hot enough for reliable ASA adhesion, the TPU is likely to stick far too hard, and if you lower the temperature to keep the TPU from bonding to the plate, the ASA will usually start to lose adhesion or warp.
How is the strength of your ASA when you print it with a chamber temperature of around 30 °C? In my case, the parts end up extremely weak regardless of how slowly I print, which makes them useless for anything other than visual prototypes. If all that matters is appearance, I would choose PLA instead, and for that kind of use PLA and TPU work together quite well.
If you can use ASA-cf, it should be easy. just underheat the chamber a little. Ive never tried it with non cf asa, but these below are 95a/ABS-GF mix. I believe I ran the chamber at 45c. Maybe for non cf, just add glue, if its not the tpu touching the bed first. If youre worried about layer adhesion, run the asa 5c hotter
Green is tpu
For ASA parts printed at room temperature or below 86 °F (30 °C), layer adhesion is poor. As a result, these parts typically fail along the layer lines. In this respect, PLA often performs even better. If your part is only loaded across the layers, printing ASA at room temperature is generally not an issue.
TPU is actually pretty temperature resistant. It can retain its shape up until 100C ish. With this ability combined with ASA you can do a lot of things under “general high temperature”
By the way, regarding ASA: I personally find ABS much better. Without an actively heated build chamber, the warping with ASA is truly terrible. I only use ASA when I need UV stability, such as for outdoor parts. Are there any other advantages of ASA that I might be overlooking?
I printed gasket from TPU 95A and it works great in terms of temperature resistance - I think I “tortured” it in a dryer at around 80°C for several hours and it was OK, but I don’t have such good experience with TPU for AMS… As an experiment, I use it to print “Flexi Clips (for Spool/Filament)”, and even at temperatures for PLA (approx. 55°C), it lost its shape and shrunk. At temperatures around 70°C, it was completely “KO”
At the end of description of my model, there are some photos from testing, where you can see that it didn’t turn out very well…
I guess they mixed too much PLA into the TPU for AMS, or other things. I agree with your experience.
You do bring up a valid point if printing at lower chamber temperatures; weaker layer adhesion. Layers are weaker as you would expect, but not bad enough to say parts aren’t functional. I try really hard not to rely upon Z strength as much as possible when making parts. If Z strength is important or parts are big enough I let the chamber heat soak up to 50c+ before printing. My H2C is hopefully going to make all that a whole lot easier.
Well, I guess today is an experiment day. I’ll share my result!
this print won’t have any TPU on the bed, it will be 20 layers up in the print.
My parts lost so much strength that using ASA filament at lower chamber temperatures was practically equivalent to throwing the filament away. For me, there is no reason to print at a temperature where the material loses a significant part of its intended mechanical properties – that simply means the wrong filament is being used for the conditions.​
Since I print functional parts that must remain structurally reliable, I may have stricter requirements than many other users. Still, if mechanical strength is not important and printing parameters are chosen outside the optimal range, it makes more sense to switch to a filament that performs better at those lower temperatures.​
From a technical perspective, ASA is formulated to work close to its glass transition region, where the polymer chains still have enough mobility for good interlayer diffusion and “welding” between layers. At chamber temperatures around 60–65 °C, the part cools more slowly, internal stresses can relax, and the layers bond much more effectively, which preserves the material’s inherent tensile and impact strength. At about 30 °C, each extruded strand solidifies too quickly, interlayer diffusion is limited, and residual stresses and micro‑cracks increase, so layer adhesion and effective strength can drop on the order of a few tens of percent compared to prints done in a properly heated enclosure.​
In that situation you are no longer getting the “engineering‑grade” behavior ASA is chosen for, and the material becomes a poor fit for critical functional parts. It is therefore often better to choose a filament whose recommended processing window matches your actual ambient temperature – for example materials tuned for open-frame printing at room temperature – instead of forcing ASA to run far outside its ideal process conditions
If the only reason for using ASA is UV protection, there are nice UV‑protective clear coats you can use instead. Just spray the model two or three times after it is finished and you get UV protection similar to ASA. If you get micro‑cracks from printing at too low a temperature and then use that model outdoors, you may be in for a surprise when you see what the weather can do with those micro‑cracks.
