Print fabric on a stock FDM printer: DefeXtiles and deliberate under-extrusion
MIT's DefeXtiles sets flow so low the line breaks into a tulle-like mesh of PLA or TPU on an ordinary printer. The settings, your first piece, and the limits.
- DefeXtiles uses under-extrusion, normally a failure, on purpose. At an extrusion multiplier of about 0.25–0.4, plastic forms globs joined by fine strands: a sheet about 0.29 mm thick.
- Start with a hollow cylinder, one 0.45 mm wall, then cut it open. It is easier than a flat sheet, which needs support pillars.
- Lower flow gives a sparser, more flexible fabric. Higher speed makes the pattern uneven but stretchier. For complex shapes, raise flow or slow down.
- In the paper, TPU was the toughest and most flexible but hard to print. PLA and nylon print easily; PETG and ABS gave brittle fabric.
DefeXtiles is a technique from the MIT Media Lab that makes an FDM printer extrude too little plastic on purpose. Instead of a solid wall, the plastic forms small globs joined by very fine strands, giving a see-through sheet that looks like tulle. It is thin, it bends and it stretches a little, even in PLA, on an ordinary printer with no hardware changes or special software.
The work was published at ACM UIST 2020. All numbers here come from the paper, mostly tested on an open-frame bed-slinger with a 0.4 mm nozzle. Your printer may need different values.
Why too little plastic makes fabric
At an extrusion multiplier (EM, or flow ratio) of 1.0, each line is full. Drop it far enough and there is not enough plastic for a continuous line. Instead:
- The plastic gathers into small globs that land on the globs of the layer below, stacking into thin vertical columns.
- Between globs, the nozzle drags out very fine strands that tie the columns together.
The researchers call this glob-stretch printing. The extrusion rate stays constant; it does not push extra plastic at each column. The globs appear because there is too little material for a solid wall but just enough for the layers to bond now and then.
Why does stiff PLA bend? The many gaps mean far less material is being bent than in a solid sheet of the same thickness, and the fine strands between columns act like hinges that flex in-plane when pulled. It is the same idea as kirigami, where cuts in paper let it stretch.
The result is a sheet about 0.286 mm thick and translucent. Columns lean against the nozzle’s direction of travel; alternate the direction each layer and they stand straight.
The settings in the paper
The table was printed at 1,250 mm/min (about 21 mm/s) with a 0.4 mm nozzle, except conductive PLA at 0.6 mm.
| Material | EM | Nozzle | Bed | Result |
|---|---|---|---|---|
| PLA | 0.25 | 215 °C | 50 °C | easy, balanced |
| PETG | 0.35 | 240 °C | 90 °C | brittle, not recommended |
| TPU | 0.30 | 220 °C | 50 °C | toughest and most flexible, hard to print |
| ABS | 0.35 | 255 °C | 100 °C | brittle, not recommended |
| Nylon (PA) | 0.40 | 250 °C | 75 °C | easy, balanced |
| Conductive PLA | 0.85 | 215 °C | 50 °C | for capacitive touch traces |
TPU needs a precisely set first-layer height and EM, so the authors suggest it only where durability really matters.
Worked example: how much flow is left
Using the paper’s test settings: 0.20 mm layers, 0.45 mm line width, 1,250 mm/min.
- Speed in mm/s: 1,250 ÷ 60 ≈ 20.8 mm/s.
- At EM 1.0 the flow would be 0.45 × 0.20 × 20.8 ≈ 1.87 mm³/s.
- At EM 0.25 (PLA) it drops to 1.87 × 0.25 ≈ 0.47 mm³/s, a quarter.
That is far below the max volumetric speed of a typical hotend (see print speed vs quality). Melting is not the problem; steady extrusion at such a small rate is, and that varies from printer to printer.
Your first piece: a hollow cylinder, cut open
The paper says the easiest route is a hollow cylinder you cut open afterwards. No support pillars needed.
- Model a hollow cylinder with a 0.45 mm wall, equal to the line width, so the slicer prints a single wall with no top, bottom or infill.
- Set that object’s flow ratio to 0.25–0.3 (PLA), 0.2 mm layers, 0.4 mm nozzle.
- The researchers lowered the nozzle about 0.1 mm so the first layer was full and stuck, and put a thin layer of glue on the bed. After the first layer, glob-stretch starts by itself.
- When it is done, knock it off with one quick strike of a scraper at the base, then cut the cylinder open with sharp fabric scissors.
For a truly flat sheet, the paper printed an upright sheet between two 5 × 5 mm pillars at EM 1.0 to keep it from leaning, with the fabric printed before the pillars in each layer for a more even result. Cut the pillars off afterwards.
Lowering the nozzle 0.1 mm changes the whole printer. Put the Z-offset back when the fabric is done (see first layer).
EM and speed: the trade-offs
The paper’s tests on 5 × 5 cm PLA swatches at 210 °C found:
| Change | Effect |
|---|---|
| EM down to about 0.8 | an even gap pattern begins |
| EM lower still | sparser, longer and thinner strands, more flexible |
| EM about 0.3 (in that test set) | layers stop bonding; the print fails |
| slow (1,500 mm/min) | even, neat pattern, but breaks under little tension |
| faster (6,750 mm/min) | uneven pattern, thinner strands, far stretchier |
The materials table uses EM 0.25 for PLA, while this test set failed around 0.3, so the sweet spot moves with speed and printer. The authors say to tune for your own printer and filament. Do it the way you tune a new filament: several small swatches, one change at a time.
For complex shapes, overhangs or sharp corners, raise EM slightly or slow down. Overhangs past 45° would not print, same as normal prints. Sharp corners caused occasional failures; round them off in the model.
What you can do afterwards
- Iron it on. It bonds to real fabric like an iron-on patch. Put a PTFE sheet or transfer paper between it and the iron.
- Remove pleats. Hold it flat and pass a hair dryer over it quickly.
- Anneal PLA. Seal it in a bag, put it in 70 °C water for 30 minutes, turn the heat off and let the water cool before taking it out. Tensile strength improves noticeably but it bends less. Flat sheets only; heat distorts 3D shapes.
- Touch circuits. A multi-material printer can lay conductive PLA traces into the fabric. The paper’s lampshade dims when you touch its pleats.
Mind the hot water and iron, work on a steady table, and keep this step for adults if kids are around.
Common mistakes
- Starting with a thin flat sheet and no pillars. It topples halfway. Start with a cylinder.
- Dropping flow without watching the first layer. It does not stick, and the whole piece lets go.
- Forgetting to restore the Z-offset. The next print drives the nozzle into the bed.
- Using PETG or ABS. The fabric is brittle and snaps when bent.
- Expecting real cloth. Strength across the layers is about a fifth of the horizontal strength. Design the pull to run horizontally.
Sources
FAQ
Do I need special slicer software?
No. The researchers used an ordinary slicer split into two processes. In a current slicer, lowering the flow ratio or extrusion multiplier for that object does the same job, but you will need to tune it for your printer and filament brand.
Can you actually wear it?
The team made prototype skirts, but they call it a quasi-textile: it is not as soft as cloth and does not stretch in every direction. It suits lampshades, decoration, fashion prototypes and toys better than everyday clothing.
Does PLA fabric tear easily?
In the paper's tests a PLA sheet held 4.5 kg along the horizontal direction but 900 g along the layer (vertical) direction. The layers are the weak point, so design for pull along the horizontal.
Circuits and code were tested on sample boards. Boards differ in pin layout, so check your board's pinout before you power anything.