Bambu Lab AMS
Will a Third-Party Spool Fit in Your AMS? Check Two Numbers First
Bambu publishes the spool sizes its AMS units accept. This page gives the two numbers to check on a third-party spool, where to find them, and what to do with a spool that falls outside them.
The short answer
For the AMS, AMS 2 Pro and AMS HT, two numbers decide whether a spool fits: its width across the flanges and its outside diameter. Bambu gives the same limits for all three: 50–68 mm wide and 197–202 mm in diameter. A plastic spool with both numbers inside those ranges fits the AMS as Bambu describes it. A cardboard spool can go in too, but Bambu strongly advises a spool adapter or adapter ring for it. Bambu's aim is to reduce the risk of slipping and of cardboard debris left in the AMS. If either number falls outside the range, a small spool can take a printed adapter. A spool that's too big feeds from outside the AMS, or its filament moves to a spool that fits.
The AMS lite, used with the A1 and A1 mini, is sized differently. Bambu gives it a width of 40–68 mm and an inner diameter, meaning the center hole, of 53–58 mm. It gives no outside diameter for the AMS lite, and no hole size for the other three units. A spool outside those limits can feed from outside the AMS lite as an external spool. Or its filament can move to a Bambu reusable spool, which Bambu's wiki staff say fits the AMS lite.
Go by the unit, not the printer. Bambu says the AMS lite doesn't work with X1 or P1 printers. A1 printers, though, can also run an AMS 2 Pro or AMS HT through the A1 Series AMS Hub. Check which unit you own before you use the table below.
| Unit | Spool width | Outside diameter | Center hole | Where Bambu gives it |
|---|---|---|---|---|
| AMS | 50–68 mm | 197–202 mm | Not given | Notes for AMS |
| AMS 2 Pro | 50–68 mm | 197–202 mm | Not given | AMS 2 Pro specifications |
| AMS HT | 50–68 mm | 197–202 mm | Not given | AMS HT specifications |
| AMS lite | 40–68 mm | Not given | 53–58 mm | AMS lite FAQ |
What the numbers describe
For the AMS, AMS 2 Pro and AMS HT, both of Bambu's limits are outside measurements of the spool. Bambu's loading guide mentions the AMS rollers and the gear that drives them. Polymaker, a filament maker, describes how the AMS and AMS 2 Pro turn a spool: instead of holding it on a central spindle, motorized rollers press on its outer rim. Polymaker says that constant roller contact can wear a cardboard rim into dust or let the spool slip, especially when the spool is nearly empty. Those are the two problems Bambu gives as its reason for an adapter on cardboard spools.
The AMS lite works differently. Each slot holds the spool on a rotating holder with three spool claws, and Bambu gives its limits as width and center hole, with no outside diameter.
Where to find the numbers for the spool you found
- Start with the maker's own product page, FAQ or support pages. Look for the spool's width and outside diameter, or its width and center hole for an AMS lite. A general yes isn't the same thing. Polymaker, for one, says on its wiki that its newer cardboard spools have hardened edges and now spin reliably in the AMS. The same wiki still suggests a printed adapter for a dented spool or worn AMS rollers, and gives no spool dimensions. Treat a maker's yes as a reason to check the two numbers for the weight you're buying, not as a substitute for them. A reseller's "AMS compatible" tag or a shared category name doesn't establish fit either.
- Many listings give filament diameter and net weight but no spool size. Weight tells you how much filament is on the spool, not how big the spool is, and one listing can cover several weights: Sunlu's PLA+ 2.0 page runs from 0.25 kg to 5 kg, and Polymaker's PolyLite PLA page offers 1 kg, 3 kg and 5 kg. Make sure any dimensions you find belong to the weight you're ordering.
- No numbers? Ask the seller, or measure a spool you already own from the same product line. Makers do change their spools, as Polymaker did with its edges, so check that the one you measure matches what the listing ships now. Width: across the outside faces of both flanges, at the widest point. Diameter: rim to rim through the center, with a steel rule if your calipers are too short. For an AMS lite, measure the center hole too.
- Bambu lists 1.75 mm filament for the AMS 2 Pro and AMS HT. While you're on the listing, confirm the filament diameter: 1.75 mm or 2.85 mm filament.
Cardboard spools: the adapter ring
The "Spool Adapter Ring" that Bambu's notes page links to is a free, community-made model on MakerWorld that you print yourself. It's drawn for one spool. Its designer says it wraps the edges of Overture's 1 kg cardboard spool, given as 199 × 66 mm. The stated purpose is smooth rotation and keeping cardboard debris out of the AMS. Both numbers sit inside Bambu's ranges, so for that spool the ring is there for the cardboard, not the size.
The ring's designer gives these notes for it:
- Print two, one for each flange, in basic PLA or PETG to keep shrinkage down.
- The rings wrap the rims, so they add to the outside diameter. The designer says all of their adapters come in under Bambu's 202 mm limit, and also that some users report the spool rubbing the AMS lid with the rings fitted.
- Cardboard swells in humid air and shrinks when dried, so the rings can fit tight on a damp spool and loose after a long drying session.
- Don't dry the spool with the rings on; they can warp in the heat. That matters if you dry filament inside an AMS 2 Pro or AMS HT, where the spool stays in its slot while it dries.
For another brand's cardboard spool, use an adapter drawn for that spool, follow its designer's notes, and check the diameter with the adapter fitted. Some makers point to designs themselves. Polymaker's wiki names two community-made adapters for its own cardboard spools, and the filament to print each in, with different choices for spools that will be dried at 65°C.
Small spools and oversized spools
The other model the notes page links, labeled "Spool Adapter," is the AMS Universal Small Spool Adapter, made for small spools such as 250 g, 500 g and 750 g. Its designer says the two side parts screw into each other and cover spool widths of 35–63 mm. It comes in two versions, listed as 46.5 mm and 39.5 mm in diameter. The designer narrowed it to 39.5 mm to fit more brands, such as Sunlu's 250 g spools. The two parts meet through the spool's center hole, so measure the hole before you choose a version. Both linked adapters are described for the AMS; neither designer's description mentions the AMS lite.
A spool wider than 68 mm or more than 202 mm across is outside Bambu's range for the AMS, AMS 2 Pro and AMS HT. For an AMS lite, the limits are 40–68 mm wide with a 53–58 mm hole. A spool that misses your unit's range feeds from outside it, as an external spool. Bambu's guide to large spools lists an external spool holder, a dry box, or a holder you print yourself. It names example designs on MakerWorld for the A1 and for the X1 and P1 series.
That guide sits in Bambu's X1 manual and deals with the spool holder at the back of the printer. On X1 and P1 printers, the filament buffer at the back links the AMS to the extruder. The guide warns that a large spool on the rear holder can interfere with it. Removing the buffer, the guide's first option, disconnects the AMS. On those printers the buffer serves one AMS unit, and the AMS Hub replaces it to connect up to four. The original AMS comes with a buffer when bought on its own. The AMS 2 Pro and AMS HT don't, and other printers connect differently, as Bambu's AMS 2 Pro and AMS HT FAQ sets out.
Moving the filament to a Bambu reusable spool
Bambu's notes pair their advice to use plastic spools that fit with a link to its reusable spool guide. That guide is about Bambu's own refill coils: it covers 1 kg and 250 g refills, loaded by lining up a notch on the coil's cardboard core. Winding another brand's filament across by hand is a different job. Bambu's filament guide warns that filament which has come loose and been rewound is likely to knot again. For AMS lite owners, Bambu's wiki staff have confirmed, in the comments under the refill guide, that the reusable spool fits the AMS lite.
If you do move filament over, pick the version by filament and heat. Bambu lists two:
- Low-temperature spool (up to 70°C, made of ABS): PLA and PETG.
- High-temperature spool (up to 90°C, made of ABS+PC): PLA, PETG, ABS, ASA, PC, TPU, PA6-GF, ABS-GF, PAHT-CF, PET-CF and PA6-CF.
Those lists say what each spool can carry, not what your AMS can feed; the material limits below still apply. Bambu gives the AMS 2 Pro a maximum drying temperature of 65°C and the AMS HT 85°C. The AMS HT's maximum works out to 15°C above the low-temperature spool's limit and 5°C under the high-temperature spool's. For drying targets by material, see whether your dryer reaches the temperature you need.
Before you load it
- Bambu's AMS units read RFID tags on Bambu's own filament. For any other spool, Bambu's loading guide says to set the filament type and color yourself on the printer screen or in Bambu Studio. On the AMS 2 Pro and AMS HT, Bambu ties the remaining-filament estimate to those tags.
- Size isn't the only limit. Bambu's notes for the AMS say to avoid printing flexible filaments such as TPU and TPE, "absorbent" PVA, and third-party fiber-reinforced filaments through it. The newer units' lists differ. The AMS 2 Pro and AMS HT specifications accept dried PVA and Bambu's TPU for AMS. The AMS 2 Pro also rules out Bambu's own PET-CF and TPU 95A, and other carbon- or glass-fiber filament. The AMS HT sends those, plus TPE and generic TPU, through a separate bypass outlet. The AMS lite FAQ allows TPU of 55D or harder. Check your unit's list, and see filaments the AMS can't feed.
- Bambu treats the PTFE tubes as consumables; worn tubes can cause feeding failures and filament piling up inside the AMS. For the original AMS and the AMS lite, Bambu says to replace them every two months in normal use. For the AMS, it says monthly with abrasive filaments such as carbon-fiber-filled or glow-in-the-dark filament; for the AMS lite, monthly with round-the-clock printing. For the AMS 2 Pro, Bambu gives no fixed interval. It says to replace them when feeding errors or loading resistance appear, or after long, heavy use, especially with abrasive or composite filaments.
- For the printer's side, see the five limits that decide whether your printer can run a filament.
Check it on your own equipment
These take you to the manufacturers and standards bodies the page draws on, so you can look up your exact model.
- Manufacturer specification
Bambu Lab Wiki: Notes for AMS (opens in a new tab)Bambu's AMS spool limits (50–68 mm wide, 197–202 mm diameter), its advice for cardboard spools with links to the two adapter models, and the materials Bambu says to avoid printing through the AMS. — wiki.bambulab.com - Manufacturer specification
Bambu Lab Wiki: AMS lite FAQ (opens in a new tab)The AMS lite's spool limits (40–68 mm wide, 53–58 mm inner diameter), which TPU hardness it accepts, and the filaments Bambu says to feed from an external spool instead. — wiki.bambulab.com - Official support page
Bambu Lab Wiki: Refill Filament with Bambu Reusable Spool (opens in a new tab)The low- and high-temperature reusable spools with their temperature limits, body materials and filament lists, and how 1 kg and 250 g refills load onto them. — wiki.bambulab.com - Official support page
Bambu Lab Wiki: Using a large spool on the spool holder (opens in a new tab)Bambu's options when a large spool won't sit on the printer's rear spool holder: remove the filament buffer, use an external holder or dry box, or print a holder, plus its warning about buffer interference. — wiki.bambulab.com
What this page does not tell you
- Bambu gives no center-hole size for the AMS, AMS 2 Pro or AMS HT, and no outside diameter for the AMS lite. If a spool's hole or overall size looks unusual, ask the seller or Bambu support before you rely on it.
- That the reusable spool fits the AMS lite comes from a Bambu wiki staff reply in the comments under the refill guide, not from the guide itself. If that fit matters to your plan, confirm it with Bambu support.
- The adapter figures (the Overture spool's 199 × 66 mm, the 35–63 mm width range, the 46.5 mm and 39.5 mm versions, the 202 mm clearance) and the drying, warping and lid notes are the MakerWorld designers' own, not Bambu or Overture specifications. Check the fit on your own spool with the adapter on.
- Polymaker's statements about its spools, and its description of how the AMS and AMS 2 Pro turn a spool, are Polymaker's own, and its pages give no spool dimensions. Measure a spool or ask the seller for the numbers.
- Spool designs change. A maker's figure or your own measurement applies to the spool it was taken from, so recheck when you order a new batch or a different weight.
Sources
22 documents, each with the facts on this page it supports. Manufacturers revise specifications, so every source is dated — open it before you buy.
- AMS: spools 50–68 mm wide and 197–202 mm in diameter (table row AMS: width 50–68 mm, outside diameter 197–202 mm, source Notes for AMS).
- Bambu gives no center-hole size for the AMS (table: AMS center hole 'Not given').
- A plastic spool whose width and diameter fall inside Bambu's ranges fits the AMS as Bambu describes it.
- For cardboard spools Bambu strongly advises a Spool Adapter or Spool Adapter Ring to reduce the risk of slippage and debris left in the AMS.
- A small spool outside the range can take a printed adapter; a spool that is too big feeds from outside the AMS or its filament moves to a spool that fits.
- Polymaker's two problems (dust, slipping) match the two reasons Bambu gives for an adapter (slippage, debris).
- A maker's general yes is not a substitute for the width and diameter; a reseller tag or shared category name does not establish fit.
- Measure width across both flanges, diameter rim to rim, and the center hole for an AMS lite.
- Bambu's notes page links 'Spool Adapter Ring' to MakerWorld model 17373 and 'Spool Adapter' to MakerWorld model 23018.
- A spool wider than 68 mm or more than 202 mm across is outside the range for the AMS, AMS 2 Pro and AMS HT.
- A single original AMS bought on its own comes with a filament buffer.
- Bambu highly recommends plastic spools that fit and links its reusable-spool guide from that advice.
- Bambu's notes say to avoid printing flexible materials, including TPU, TPE and absorbent PVA, through the AMS.
- Bambu's notes say to avoid overly hard or brittle materials, including third-party fiber-reinforced filaments, in the AMS.
- AMS PTFE tubes are consumables; worn tubes can lead to feeding failures and filament accumulation inside the AMS.
- AMS 2 Pro: spool width 50–68 mm, diameter 197–202 mm (table row AMS 2 Pro, source AMS 2 Pro specifications).
- Bambu gives no center-hole size for the AMS 2 Pro (table: 'Not given').
- Bambu lists 1.75 mm filament diameter for the AMS 2 Pro.
- The AMS 2 Pro dries filament with the spools in place, rotating them during drying.
- The AMS 2 Pro box contains no filament buffer.
- AMS 2 Pro supports dried PVA and Bambu TPU for AMS; not supported: TPE, generic TPU, damp PVA, Bambu PET-CF and TPU 95A, and other carbon- or glass-fiber filament.
- AMS HT: spool width 50–68 mm, diameter 197–202 mm (table row AMS HT, source AMS HT specifications).
- Bambu gives the same spool limits for the AMS, AMS 2 Pro and AMS HT.
- Bambu gives no center-hole size for the AMS HT (table: 'Not given').
- Bambu lists 1.75 mm filament diameter for the AMS HT.
- The AMS HT dries filament with the spools in place, rotating them during drying.
- The AMS HT box contains no filament buffer.
- AMS HT supports dried PVA and Bambu TPU for AMS; its bypass outlet takes TPE, generic TPU, Bambu PET-CF and TPU 95A, and other carbon- or glass-fiber filament; only damp PVA and BVOH are unsupported.
- AMS lite: spools 40–68 mm wide with an inner diameter of 53–58 mm (table row AMS lite: width 40–68 mm, center hole 53–58 mm, source AMS lite FAQ).
- Bambu gives no outside diameter for the AMS lite (table: 'Not given').
- The AMS lite is used with A1-series printers, including the A1 and A1 mini.
- A spool outside the AMS lite's limits can feed from outside it as an external spool.
- The AMS lite is incompatible with X1 and P1 series printers.
- The AMS lite FAQ allows TPU of 77D, 55D or higher hardness and rules out 95A, 85A, 83A, 80A or softer.
- An AMS 2 Pro connects to an A1-series printer through the separately bought A1 Series AMS Hub.
- AMS 2 Pro RFID reads tags on official Bambu filament and enables remaining-filament estimation.
- An AMS HT connects to an A1-series printer through the separately bought A1 Series AMS Hub.
- X1 and P1 printers connect an AMS HT through a buffer for one unit or an AMS Hub for several.
- H2-series printers have a built-in feeding buffer.
- The AMS HT's maximum drying temperature is 85°C.
- AMS HT RFID reads tags on official Bambu filament and enables remaining-filament estimation.
- Bambu's loading guide mentions the AMS rollers and the drive gear that engages them.
- For unofficial spools, filament information must be set manually on the screen or in Bambu Studio.
- Polymaker describes the AMS and AMS 2 Pro as turning the spool with motorized bottom rollers pressing on its outer rim, unlike holders that support a spool on a central spindle.
- Polymaker says continuous roller contact can produce paper dust or cause slipping, especially when the spool is nearly empty.
- Polymaker says its spools use high-density rigid cardboard and reinforced, rubber-coated rims.
- Polymaker's wiki still suggests a spool adapter for worn AMS rollers or spools dented in transit or heavy use.
- Polymaker's wiki names two community-made adapters for its cardboard spools (Model A by AU3D, Model B by Swaegner) and the filament to print each in, with separate choices for a 65°C drying cycle.
- Each AMS lite slot holds the spool on a rotary spool holder.
- Each AMS lite slot has an RFID coil that reads the spool's tag; third-party filament properties can be edited manually.
- Each AMS lite rotary spool holder has three spool claws that secure the spool.
- For the AMS lite, replace PTFE tubes every two months in normal use and monthly for 24/7 printing.
- Polymaker says its newer cardboard spools have hardened or sealed edges and now spin reliably in the AMS.
- Neither Polymaker wiki page gives spool dimensions.
- Makers change their spools over time (Polymaker introduced new cardboard spool designs).
- Sunlu's PLA+ 2.0 page offers 0.25, 0.5, 1, 2, 3 and 5 kg and gives no spool dimensions.
- Net weight gives the amount of filament, not the spool's size.
- Polymaker's PolyLite PLA page offers net weights of 1 kg, 3 kg and 5 kg, with no spool dimensions shown.
- Many filament listings give filament diameter and net weight but no spool size.
- The linked Spool Adapter Ring is a free MakerWorld model by the user DesignCraft, published as user content.
- The ring's designer says it wraps the edges of an Overture 1 kg 199 × 66 mm cardboard spool for smooth rotation and to keep cardboard debris out of the AMS.
- 199 mm and 66 mm fall inside Bambu's 197–202 mm and 50–68 mm ranges.
- The designer says to print the ring twice, one on each side, in basic PLA or PETG to minimize shrinkage.
- Because the rings wrap the rims, they add to the outside diameter.
- The designer says all of their adapters are under the 202 mm AMS clearance limit.
- The designer says some people report their spools rubbing the AMS lid with the adapters attached.
- Cardboard expands with humidity and contracts when dried, so the adapters can fit tight or loose.
- The designer says not to dry the spool with the adapters attached because they can warp in the heat.
- For another brand's cardboard spool, an adapter drawn for that spool is needed, and the diameter should be checked with it fitted.
- The ring designer's description refers to the Bambu Lab AMS and does not mention the AMS lite.
- The linked Spool Adapter is the 'AMS Universal Small Spool Adapter', made for small spools such as 250 g, 500 g and 750 g in the AMS.
- Its two side parts screw into each other and cover spool widths of 35–63 mm.
- It comes in versions listed as 46.5 mm (v1) and 39.5 mm (v2) in diameter; v2 was narrowed to fit more brands such as Sunlu 250 g spools.
- The two parts meet through the spool's center hole, so the hole should be measured before choosing a version.
- The small-spool adapter designer's description refers to the Bambu Lab AMS and does not mention the AMS lite.
- Bambu's large-spool guide lists removing the filament buffer, an external spool holder or dry box, and printing your own spool holder.
- The guide names MakerWorld example holders: a desktop holder for the A1 and a side-mounted holder for the X1 and P1 series.
- The large-spool guide is in Bambu's X1 manual and concerns the spool holder at the back of the machine.
- Large spools can interfere with the filament buffer.
- Removing the buffer as the large-spool guide describes disconnects the AMS.
- The filament buffer is at the back of the printer and connects the AMS to the tool head extruder.
- The AMS Hub replaces the filament buffer.
- The AMS RFID system identifies tags on Bambu Lab filament spools.
- On X1/P1 printers a regular filament buffer connects one AMS unit, and the AMS Hub connects up to four.
- Other printers connect differently: H2D/H2S use 4-in-1 PTFE adapters for three or more units, and a standalone P2S needs a P2S filament buffer.
- The reusable spool guide covers loading 1 kg and 250 g refills by aligning a notch on the cardboard core.
- The reusable spool guide covers loading Bambu refills and gives no steps for hand-winding another brand's filament onto the spool.
- Bambu's wiki staff replied that the reusable spool fits the AMS lite.
- Low-temperature reusable spool: up to 70°C, made of ABS, for PLA and PETG.
- High-temperature reusable spool: up to 90°C, made of ABS+PC, for PLA, PETG, ABS, ASA, PA6-GF, ABS-GF, PAHT-CF, PET-CF, PA6-CF, PC and TPU.
- The reusable spools' filament lists describe the spool, not what a given AMS unit can feed.
- 85°C is 15°C above the low-temperature spool's 70°C and 5°C under the high-temperature spool's 90°C.
- Bambu warns that filament that has unraveled and been rewound is likely to knot again.
- The AMS 2 Pro's maximum drying temperature is 65°C and the AMS HT's is 85°C.
- For the original AMS, replace PTFE tubes every 2 months in normal use and every month with abrasive filaments such as carbon fiber or glow-in-the-dark.
- For the AMS 2 Pro, Bambu gives no fixed interval: replace PTFE tubes on feeding errors, loading resistance, or after extended heavy use, especially with abrasive or composite filaments.