How do I print PVA with X1C & AMS HT?

Bambu Lab X Series Troubleshooting
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I just got a spool of PVA that I want to use as support filament for some of my prints. For the first print I didn’t bother drying it. I thought maybe it’s fine since it was still vacuum sealed. But yeah, I got a lot of stringing but the print still turned out ok as I was lucky that the stringing only caused issues in areas of the print that won’t be visible.

So for the next print I decided to dry the PVA in tha AMS HT using the standard settings for PVA. No more stringing but now the PVA just keeps snapping in the PTFE tubes all the time causing the print to pause and requiring me to clear out the tubes manually every few minutes.

The Wiki suggests to use the TPU outlet on the AMS HT but that isn’t an option if you want to use it as support filament with the X1C, as it will need to go through the AMS Hub.

I’m at a loss, any advice is appreciated.

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I have used PVA several times without any problems from AMS (Pro-2).

First, I dried it thoroughly, of course, and then simply put the spool into the AMS like any other filament. As far as I remember, I didn’t have a single problem with it -i.e., it passed through all the PTFE tubes and the AMS Hub without any issues. And for some prints, there were perhaps more than 100 filament changes—i.e., it repeatedly traveled back and forth… no issue.

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I moved the PVA from the AMS HT to the AMS 2, and so far I haven’t run again into the issue of PVA fragments clogging up the PTFE tubes. However, now the problem with my current print is that the PLA turns instantly into spaghetti as soon as it tries to attach to the PVA.

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My experience with PVA is that it is wet straight from the bag. It then rapidly picks up more moisture and will start to break when given funny looks.

So always give it a good drying run!!!

After that 1st roll, I went for BVOH (which also needs to be dryed straight from the bag as well as weekly when stored in the old AMS1) as it is more forgiving.
Never looked back :smile:
Although I mainly use PETG for PLA and vice versa these days. BVOH only for particular prints.

:crossed_fingers: & :four_leaf_clover:

Edit: Of course, also dry the PLA and make sure the z-distance is set to 0mm. And don’t be afraid to slow down to better understand/overcome the problem.

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Btw … I also switched to using PLA ↔ PETG… it works much better for me than PVA (I still have about a quarter of a spool left and I have no idea when or what I’ll use it for).

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Did you skip drying it?
Then you’ve basically unlocked “nightmare mode” – every problem you can imagine, plus a few thousand more.

Even slightly moist PVA can and will cause trouble; it’s one of the few filaments that very clearly punishes you for not drying it properly.

I regularly print entire models in PVA with zero issues – and that’s with non-Bambu, non-premium stuff, not Bambu Lab’s crazy expensive PVA. The difference is that my PVA is absolutely bone dry, and I never even handle it with bare hands.

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If, like me, you enjoy fishing, you can 3D print bait containers that dissolve in water. Fill them with dry feed and a small stone and cast them out — it’s an easy way to bait the exact spot you want.

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That’s a great idea—to be honest, I haven’t been fishing for XY years, but when I used to go, I used to buy these things (which dissolve in water) for a lot of money. And now I have this material at home and it never occurred to me that I could use it for that. Thanks for “waking me up” :slight_smile:

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If your pva has a yellowish tint at all its still wet.

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I gave that a try. It turned out not bad. The PETG came off slightly easier than “Support for PLA/PETG” does but still leaves a mark I rather not have on this print.

As I said I did skip drying for the first print which, albeit some minor stringing, turned out better than any print I had with that PVA since I dried it.

BTW, I should probably have mention, I’m using Bambu’s PVA.

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I also have two spools of Bambu Lab PVA – and once it gets wet, it behaves just as badly as any other PVA. If you are unlucky enough to touch it in that state, it will happily repay you by jamming itself into your PTFE path.

I always dry my PVA until it is bone dry before printing, otherwise it is just asking for trouble.

The fact that your first print was better than the rest simply means the filament has soaked up more moisture now. PVA is basically on a constant quest for water – if there is any humidity in the air, it will find it, get sticky, and start popping and spitting all over your build plate.

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I don’t think so. It definitely was dryer, if anything too dry to print it from the AMS HT but I could solve that problem by printing the PVA from the AMS 2 instead.

Anyway, my current problem is to get the PLA to stick to the PVA. I just had some limited success by using “normal” instead of tree supports. But if anything that produced the worst result so far:

image
image1920×772 140 KB

(Labels indicate material used for support, all except PVA used tree supports.)

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How can PVA be too dry? I’ve been printing with PVA since it first came onto the market, so we’re talking many years now. In my experience, you really can’t overdry PVA – it’s actually quite difficult to damage it by drying it “too long,” to be honest.

You’re only using it as support material, right?

I’ve printed the classic D20 in a cage using PVA and PLA as a combo.
This is my make of the D20 in a cage, which printed perfectly on my X1 Carbon (I didn’t have the H2D at that time):

If it doesn’t stick properly, it usually comes down to one or more of these factors: print speed, temperature (too hot or too cold), or some mix of both.

If you’d like, I can take a look at your project. My H2D is busy at the moment, but I can always run a test on my X1 Carbon instead.

One quick question though: how did you dry the PVA – for how long, at what temperature, and using which method?

I also assume you’ve had a look at this updated PVA printing guide from Bambu Lab:

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Since I dried it I did not experience any issues that are commonly associated with filament being wet (e.g. stringing). But instead I experienced the PVA snapping when being fed from the AMS HT. Material getting brittle is usually caused by dryness.

Yes.

That’s what I would have tried next, but looking at the picture I shared in my previous comment, I’m no longer convinced that it’s even worth it to make this project work with PVA. Ultimately, my goal is to get a uniform surface without support artifacts on an object that doesn’t have a flat side to lay it on while printing.

FWIW, this particular object does not provide a lot of surface for a tree support interface, which is probably why only normal supports seem to work here:

Screenshot From 2025-11-28 17-45-05
Screenshot From 2025-11-28 17-45-05632×488 70.2 KB

As I said in my initial post, I dried it in the AMS HT on standard settings for PVA which I believe is 80°C for 12h.

Yeah. This guide BTW suggest to use the TPU outlet on the AMS HT which is not an option if you don’t have a H2 series printer and want to print with more filaments than just the PVA. So it basically implies that you cannot print PVA as a support filament with the X1C + AMS HT. But I’m no longer concerned about that as long as I can just print it from the AMS 2 instead.

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I’d maybe put it like this:

I’m using PVA through my AMS as well, but I keep it absolutely bone-dry. PVA is a bit strange: when it has absorbed a lot of moisture it goes soft and rubbery, gets very stringy, and the supports can turn into a sticky, saggy mess. On the other hand, if you “cook” it too hot or for way too long, the material can start to degrade and then it becomes brittle and will snap easily. So PVA can feel either floppy/slimy or dry and fragile, depending on how it’s been stored and dried.

In general, when filament suddenly snaps on the spool it’s often because it has taken up moisture and weakened, not because it’s truly “too dry”. You can absolutely destroy something like ASA by drying it at high temperature for 48 hours, but that’s more about overheating and damaging the polymer than about normal drying.

Tree supports are usually a bad match with PVA and tend to make the print look messy. I’d try regular supports with tighter settings, and instead of breaking them off, let the PVA soak until it dissolves.

The D20 in a cage I mentioned is printed through the AMS on my X1 Carbon, fully covered in PVA, and it came out really clean. I did get a bit of black bleeding into the red for some reason, but the PVA itself worked exactly as it should.

As I told someone before, it’s also fun to print bait cages for fishing in PVA. Baiting almost becomes a sport of its own: first at the printer, then later at the water when you’re actually fishing.

Speaking of drying: I ran my PVA through another drying cycle in the AMS HT. I always do that before starting a new print if the filament has been idle for more than a day. I also print full models in PVA sometimes, but I use a PVA that costs me about €20 per kilo for that. Bambu Lab’s PVA is a bit too expensive to “waste” on full models in my opinion.

If you share your model and settings, I can compare them with mine. I’m running slightly different PVA settings on my H2D and I’ve never used Bambu Lab’s built-in PVA profiles, simply because they didn’t exist when I first got my H2D.

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It’s a bit ironic that they now recommend using the bypass. Before the updated guide existed, I sent them my settings and detailed information on how I print PVA on both my H2D and X1C, including photos of the results. Then they released that guide, which is mostly the opposite of what I do.

I would assume they recommend the bypass because many users are not careful enough with drying their PVA and then run into all kinds of issues when feeding it automatically through the AMS. It’s the same story with their HF recommendations – in my experience, the suggested limits are far below what they should be, regardless of filament.

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I could DM you the project file but it seems you don’t have DMs open. I’m not the creator of the model, so I don’t want to upload it publicly.

But I pretty much just imported the STL into Bambu Studio with default settings, and then turned on supports, selected PVA as support filament, and said “yes” to all settings it recommended to change.

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No, I choosed to close DM after some death threats on this forum and will not open that again.

Use this PGP-key to encrypt it

https://keybase.io/d313373_m3/pgp_keys.asc?fingerprint=6d2458b57310f9744398b2168924d5b5da251eb8

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I ended up getting reliable results with Bambu’s own PVA printing guide for the X1C, and it solved both the snapping and adhesion issues for me.​

I’ve tested both my own profiles and Bambu’s recommendations and the main extra steps I take are: fully calibrating my PVA (Flow Ratio and PA) before printing and making sure the spool is absolutely dry and stored under low humidity. I run the PVA through the AMS HT via the standard path without problems, and I also print the same way on my H2D. In my case I’m using a MAKO high‑flow hotend, so you may need to tune a bit differently on your setup.​​

What works for me is:

  • Follow the Bambu wiki for drying (80 °C for 12 h in AMS HT) and move the PVA directly into a sealed, dry environment so it doesn’t re‑absorb moisture.​
  • Use the recommended temperatures and speeds from the guide, with normal supports instead of tree supports for this kind of geometry, PVA as both support base and interface, 0 mm Z‑gap and a few interface layers.​​
  • Reduce the speed for the PVA supports and interface, and also slow down the first 2–3 PLA layers printed on top of the PVA, while not running part cooling at 100 % on those layers to avoid “spaghetti” on the interface.​​
  • Start with an XY distance around 0.3–0.35 mm and then experiment a bit: if supports bite too hard or leave scars, increase it slightly; if they don’t support well enough, reduce it a bit.​

With calibrated flow/PA, really dry PVA, a reasonable XY distance and the parameters from the Bambu wiki, the supports come out clean and dissolve evenly, even through the AMS HT and on different hotends.​​

I also ordered 1kg of Gembird PVA-filament during Black Friday, lets see if it barf at med or will work for me as a baiting filament :wink:

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