Tip for Reducing Purge  

Tip for Reducing Purge

Here's a quick tip for reducing the total purge in a print.

First, you should set your purge volumes for each pair of filaments you use to the minimum purge that will eliminate color banding. The default settings work fine for most color changes, but you may need more for some changes (such as black to white), and with many changes you can get away with less than the default (anything to black requires very little purge, for example).

Once that's done, you should arrange your filaments with the darkest color on Filament 1, and in approximate order from dark to light with the lightest filament on the highest numbered input.

The reason for this is that Slic3r will generally go through the extruders in sequential order on each layer. Filament 1 gets printed first, then 2, etc., and it generally takes more (sometimes a lot more) purge to go from dark to light than from light to dark.

It takes a lot less purge to go from a dark color to a light color if there's an intermediate shade in between, so by ordering your colors this way and making sure your purge volumes are properly set up, you may be able to save quite a lot of purge.

For example, suppose you're printing in black, grey, and white. You want the transitions (where possible) to be arranged as:

Black -> grey -> white -> black

This will take less total purge than Black -> white -> grey -> black.