From what I have heard, the BCN Sigma (an IDEX setup with purge buckets on each side) has one of the better working purge processes for multi-material out there. I went looking for information on how they do it and came across this post on the Duet forums. It’s a pretty interesting approach (tuning the purge length based on idle time) and has some merit. Unfortunately the thread doesn’t really talk about ways this could be done in RepRapFirmware. It also requires both the idle time and filament profile to work well (since the time depends on the filament type as well). Any thoughts on their approach? Has anyone seen what BCN actually use for the wiper in their purge system, I haven’t been able to find much information on that either. My feeling about their purging working well isn’t based on direct experience so I’d also be curious if others have seen it in action. Obviously the reason for the interest is trying to get a better purge process for the Toolchanger. I do like the idea of purging being based on idle time since with small extrusions of different colours right now you could often get away with no purge but it will always purge the full amount.