TPU for AMS: checking the exact filament and feeder combination

Why the word TPU tells you nothing about AMS compatibility

Bambu Lab sells several products with TPU in the name, and each carries its own compatibility line. The AMS 2 Pro page lists TPU for AMS among supported filaments. The same page puts Bambu TPU 95A and generic TPU in the not-supported column. Two members of the same family land on opposite sides of the table.

The TPU 85A and 90A page narrows things further. It states AMS HT Compatible and, in the next line, AMS 2 Pro, AMS, AMS lite NOT Compatible. These two filaments, described by Bambu as the softest in its lineup, don't go through any multi-spool AMS according to the manufacturer.

The practical takeaway: before you add a spool to your cart, read the Accessory Compatibility line on that exact product page. If you're new to flexibles, the TPU filament guide covers the material itself. This page sticks to one commercial question: which SKU goes in which feeder.

What the TPU 85A and 90A page says about the AMS HT

The TPU 85A / 90A product page repeats the same rule three times: AMS HT compatible, AMS, AMS lite and AMS 2 Pro not compatible. It adds that the AMS HT requires reading the wiki for feeding instructions. In other words, the stated compatibility comes with a procedure, not a plug-and-play promise.

On the printer side, the page separates the two hardness grades. TPU 90A is listed as compatible with the H2S, H2D and H2C through the right filament inlet only, plus the X, P and A series. TPU 85A carries the same list minus the A series. Multi-material printing with PLA or PETG is limited to TPU 90A on the H2D and H2C, per the same page.

Nozzle rules apply too. TPU 85A is recommended for 0.6 mm and 0.8 mm and listed as not supported on 0.2 mm, 0.4 mm and the High Flow nozzle. TPU 90A adds 0.4 mm to the recommended list but stays excluded from 0.2 mm and High Flow. Our guide to 3D printer nozzles helps you pick the right diameter.

What the AMS 2 Pro page says about flexible filaments

The AMS 2 Pro page spells out its supported printing materials: PLA, PETG, ABS, ASA, PET, PA, PC, dried PVA and BVOH, PP, POM, HIPS, Bambu PLA-CF, PAHT-CF and PETG-CF, support materials for PLA and PETG, and TPU for AMS. The not-supported list includes TPE, generic TPU, Bambu PET-CF, Bambu TPU 95A, and any filament containing carbon or glass fiber.

The same page describes drying up to 65 °C and marks TPU for AMS with an asterisk. Per Bambu Lab, asterisked materials need a higher drying temperature and the AMS 2 Pro cannot dry them completely. The page points to the AMS HT for better drying performance. It also notes the maximum drying temperature is only reached when ambient temperature is above 25 °C.

Keep the distinction in mind: being able to feed a TPU and being able to dry it properly are two separate claims on this page. For drying options outside the AMS, see the filament dryer guide.

Reading the matrix: which SKU in which feeder

Cross the two pages and you get a simple matrix. TPU 85A and 90A go in the AMS HT only. Bambu TPU 95A sits on the AMS 2 Pro exclusion list. TPU for AMS is the only flexible SKU the AMS 2 Pro page calls supported, with a drying caveat.

The pages provided don't cover every case. They don't say how TPU 95A behaves in the AMS HT, or how TPU for AMS behaves in the original AMS or AMS lite. Don't infer anything from those gaps: a regional page or an excerpt can omit a line. Check the relevant product page when you buy.

The AMS 2 Pro page also notes that an X1 or P1 printer can chain up to four AMS units, mixing AMS HT, AMS and AMS 2 Pro. A workshop can dedicate one AMS HT to flexibles and keep an AMS 2 Pro for rigid filaments. The table below summarizes the documented lines.

Loading, unloading and nozzles: the conditions that come with compatibility

AMS HT compatibility doesn't excuse you from settings. The TPU 85A / 90A page asks you to keep the default max volumetric speed, turn off Flow Dynamics Calibration, and avoid raising print speed. It also says all parameters are already preset in the Bambu profile.

Unloading differs by machine. On the X and P series, Bambu Lab says not to press Unload when switching filaments, because uncut TPU residue can get stuck in the extruder. The documented procedure is to heat the nozzle to 250 °C, retract through extruder control, and pull the filament out by hand. On the H2 series, auto-retraction via Unload is allowed, but Bambu asks you to maintain the filament cutter on the right inlet since it wears faster with TPU.

The Prusa Knowledge Base, writing for its own printers, backs the general logic: print slowly, reduce or disable retraction, and keep the filament dry. It also warns that automatic filament change may not work properly with flexibles. For retraction tuning, see our retraction settings page.

What to do when your AMS doesn't match your TPU

Option one: feed the spool directly, bypassing the AMS. Bambu's pages list printer compatibility independently of the AMS, so an X1 or P1 can run TPU 90A from the external spool holder. You lose automatic changes but skip the long path and bends of the feeder.

Option two: add an AMS HT dedicated to flexibles. The AMS 2 Pro page names it as the better dryer for asterisked materials, and the TPU 85A / 90A page lists both filaments as AMS HT compatible. This adds an accessory to your setup, and the startup budget tool helps you place it within your overall spend.

Option three: pick the SKU instead of the feeder. If you want flexible in an AMS 2 Pro, the only SKU its page calls supported is TPU for AMS. Verify drying and firmware conditions at purchase, because Bambu Lab flags that these points can change over time.

Sources and limits

• TPU 85A / TPU 90A | Bambu Lab EU Store
• Bambu Lab AMS 2 Pro - Automatic Material System | Bambu Lab EU Store
• Flexible materials | Prusa Knowledge Base Prusa Prusa Prusa

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.