An AMS-style system feeds several filaments into one nozzle, so every color change purges the old color and creates waste. A tool changer gives each color its own nozzle, so it avoids that purge but adds a mechanical head swap. Which one wastes less depends on how many color changes your prints have.
"AMS" is the common shorthand for multi-spool systems that feed a single nozzle. "Tool changer" means a printer with several toolheads. Both print multicolor. They get there in opposite ways.
How an AMS-Style System Works
A feeder holds several spools and loads the one the print needs into a single hotend. To switch colors, the printer retracts the current filament, loads the next, and then extrudes until the new color runs clean. That last step is the purge, which ends up on a purge tower or in a waste bin. See Purge Towers Explained for the mechanics.
Strengths
- Lower hardware cost and a simple print head.
- Several units can be combined for more than four colors.
Trade-offs
- Waste grows with every color change.
- Each change includes unloading, loading and purging, which takes time.
How a Tool Changer Works
A tool changer has several toolheads, each with its own nozzle and filament. The printer picks up the head it needs, prints, returns it and picks up the next one. No filament moves in or out of a shared nozzle, so there is no color-clearing purge.
Strengths
- No color-clearing purge.
- Different heads can run different materials and temperatures.
Trade-offs
- Docking and undocking is a mechanical handoff that wears and has to be realigned.
- Each toolhead needs its own offset calibration.
- Hardware is more complex, so printers cost more.
Side by Side
| AMS-style (single nozzle) | Tool changer | |
|---|---|---|
| Nozzles | 1 | One per color |
| Color-clearing purge | Yes, every change | No |
| Waste as color changes increase | Grows | Does not grow the same way |
| How a change works | Unload, load, purge | Dock one head, pick up another |
| Calibration | One nozzle | Offset per head |
| Colors | Expandable with more units | Limited by head count |
| Hardware complexity | Lower | Higher |
Which Wastes Less?
On prints with few color changes, the difference can be small. As the number of changes goes up, the single-nozzle system keeps purging, and the gap widens. We weighed it on the same model: How Much Filament Does Multicolor Printing Actually Waste?
A Third Option: Independent Toolheads
There is another way to give each color its own nozzle without swapping heads. In an independent-toolhead design, all heads stay mounted on the machine, and idle heads park at the ends of the axis. Quadro works this way. Read how Quadro coordinates four independent toolheads and why it doesn't purge.
How to Choose
- Mostly one or two colors, tight budget: an AMS-style system can be enough.
- Many colors or frequent changes, waste matters: separate nozzles per color pay off.
- More than four colors: AMS-style units can be combined.
- Different materials in one print: toolheads at different temperatures.
For the full comparison across all designs, see our multi toolhead 3D printer buying guide.
Key Takeaways
- AMS-style systems share one nozzle, so every color change purges.
- Tool changers use one nozzle per color, so there's no color-clearing purge, but they add a head swap.
- The more color changes a print has, the bigger the waste gap.
- Independent toolheads give each color its own nozzle without swapping heads.
Curious about independent toolheads? See Quadro or visit the Kickstarter page.
3. FAQ
What is the difference between an AMS and a tool changer? An AMS-style system feeds several filaments into one nozzle and purges between colors. A tool changer has several toolheads, each with its own nozzle, so it doesn't need to purge to change color.
Does a tool changer waste less filament than an AMS? Usually, on prints with many color changes, because it has no color-clearing purge. On prints with few changes, the difference can be small.
Is a tool changer faster than an AMS? A head swap avoids unloading, loading and purging filament, so changes are generally quicker. Real print time depends on the model and printer.
Can an AMS print more than four colors? Several units can be combined for more colors. A tool changer is limited by its number of toolheads.
Are there printers that avoid both purging and head swapping? Yes. Independent-toolhead designs keep every head mounted on the machine, with its own nozzle, and park idle heads at the ends of the axis. Quadro is one.
