How To Reduce Purge Waste in Bambu Studio

Reducing filament waste is something you’ll want to optimize when printing multicolor models. 3D printers have to purge filament between color changes to prevent color bleeding. But all those color changes create a mess of wasted plastic on your desk. But the good news? There are a few simple tricks in Bambu Studio that can help cut that waste way down without messing up your print quality.

I’ve been experimenting with settings in Bambu Studio and have been able to reduce purge waste in Bambu Studio by up to 98% on certain prints. Whether printing one model or a whole batch, you can make things more efficient and save money on filament.

What is Purge Waste?

Purge waste is the filament your printer pushes out when it switches from one color to another. When you’re doing a multicolor print, the hotend needs to clear out the old filament before switching to a different color or material. If the hot end doesn’t purge the old filament, you’ll have streaks or smudges where the colors bleed together.

Even worse, improper purging can destroy layer adhesion and print quality if you switch between incompatible materials, such as PLA and ABS.

Bambu Labs Automatic Material System (AMS) is excellent for multi-material prints, but every color change means purging some filament that goes to waste. The purging process keeps your print looking sharp and means your printer uses extra filament. Additionally, multicolor prints take much longer due to the time spent swapping filaments.

While some purge is unavoidable, knowing why it happens and when it matters is the first step toward dialing things in and wasting less.

How To Reduce Purge Waste in Bambu Studio

Bambu Studio provides many tools to cut and purge waste. These changes don’t take long to set up, saving you filament and reducing print times without impacting print quality.

In the photo above, you can see the effect of reducing flushing volume, raising the layer height, and enabling the flush to infill and support. By implementing these tips, I was able to reduce the flushing volume by more than 60% and save 3.5 hours of printing.

Reduce the Flushing Volume Multiplier

The first change to make is to adjust the flushing volume multiplier. By default, Bambu Studio purges 280mm³ of filament every time it changes colors. In my experience, this number is more than you need, especially if you switch from one dark color to another.

First, turn on Auto Calculation in the Flushing Volumes settings. The auto calculation adjusts the purge volume based on the differences between the two colors. It won’t purge as much for low-contrast swaps, such as red to orange, but it increases the flushing volume when transitioning from a dark to a light color to reduce bleeding.

AutoCal can sometimes make things worse on high-contrast changes, so I always pair it with a reduced global flushing multiplier.

I typically use a global multiplier of 0.6, or 60%, but you can go as low as 0.5 (or 50%) if you’re printing in one material. You’ll still get clean transitions, but you won’t be wasting a ton of extra filament. If you notice any faint color bleeding, adjust it slightly or run a test print first.

Flush Into Infill

This setting lets your printer purge filament right into the inside of your model, inside the model where you can’t see it. You’ll find it under the “Other” tab in Bambu Studio. Your printer needs filament to add infill, so why not use that area to purge the nozzle?

I enable this setting on almost all my prints, which rarely affects the model’s appearance. You only need to be careful if you have light colors where the infill colors may shine through the print.

Flush Into Support

If your print needs support, you can tell your Bambu Lab printer to purge into the supports by enabling “Flush into Object Support.” This setting is the easiest way to reduce purge volume and doesn’t impact the finished print quality.

Also, consider that this setting won’t help if your model lacks support or if you’re using custom ones. But if you’re using generated supports, the support towers are a great way to reduce purge waste.

Flush Into Another Object

Another trick is to add a small object next to your print and have your printer purge old filament into the model. Using another object as a flush tower is a great way to reduce filament waste, as long as you don’t mind the second object being multiple random colors.

Many people use a simple cube, but I like to make it worthwhile. I often throw in a model I’ll paint later because I don’t care about the filament color.

Tip: To avoid stringing or messiness, leave space between your main print and the purge object.

Print Multiple Objects at Once

Here’s a clever hack: If you’re printing small items, print multiple at once. The printer still swaps filaments, but you’ll save on purge waste by printing several models simultaneously instead of one model per print job.

I printed five multicolor keychains this way, and the amount of purge material was almost the same as printing just one. That means each keychain had way less waste per piece.

You might get a bit of stringing between models, but it’s nothing a quick heat gun pass won’t fix.

Print By Object

If you’re printing several models in one color, you can change the print settings from print by layer to print by object. Instead of switching between objects every layer, this setting instructs your printer to finish one object before moving to the next.

Printing by object is a little-known setting that helps reduce how often it needs to purge. And it works best if you’re printing multiple objects in one solid color.

I used this when printing two small figurines, saving time and filament compared to printing them all at once layer by layer. Instead of purging filaments with each layer, the printer only purges once when switching models.

As a little bonus, the reduction in purging also improves print times.