That Pesky Collapsible Stopper

Bambu Lab P1 Series General Discussions
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Hey Bambu,

I have another brilliant idea for a software/firmware modification to the P1S and X1C printers. As it exists right now, the P1S and X1C reserve a region of 18x28 mm for the AMS filament cutter to operate properly.

My suggestion is a slight modification to the firmware as well as an update to Bambu Studio. Both modifications do roughly the same thing but in different ways.

First off, the firmware update would prevent (or perhaps simply warn) the user when they are about to move the print head into the reserved region. I have accidentally engaged the filament cutter and taken the magnetic front off of the print head with a sequence of naive X/Y movements. The quick fix is not to let the user move the print head toward the back of the machine while it is in this region. Movement forward into the region will collapse the stopper. Movement forward while in the region should not be problematic but may require investigation. Movement left should engage the rules of the restricted region and may engage the cutter, but it will not remove the magnetic cover. Movement to the right will disengage the cutter and eventually clear the region. Disallowing movements in the firmware that engage the cutter or remove the face plate would be ideal for new users and anyone who doesn’t know about this limitation.

Second, apply the same rules in Bambu Studio for Gcode that it generates. This would allow the full use of the print area, but it would restrict movement of the head back while in the reserved region. Again, movements forward and to the right are safe maneuvers. Movement to the left is accepted but engages the restrictions of the reserved region (and possibly the cutter mechanism). Movement back while in the reserved region should be prevented. This would allow full use of the area and collapse the stopper each time the head was laying filament in the restricted area while still allowing movement to the left that engages the cutter and is useful in AMS prints.

I hope this makes it into future updates, so that users may enjoy the full size of the build plate without needing to perform custom (and often temporary) modifications to engage the full plate area.

Thanks for reading. Discuss!

1 Like
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Adding to this, I think the collapsible stopper should be moved to the back left in future iterations of Bambu printers. The reason for this is so that you can print multiple models in different materials on the same build plate without constantly swapping filament.

By moving the collapsible stopper to the back left (and collapsing when approached from the front), this minimizes gantry movement when performing filament swaps. Instead of moving from the back, where filament is purged, to the front, where the stopper engages the cutter, the filament would be purged at the back, next to the position where the cutter can be engaged by the stopper. The clearest benefit to me is that all filament change movements are done at the back and could not interfere with an existing printed model on the build plate.

If someone wants to print two different models in two different materials (or colors of the same material), they currently have two options (and a half):

  1. Print models one at a time, clearing the built plate between prints.
  2. Print models simultaneously, swapping filament every layer.
    2.5) Print model at front of plate, cut filament, print model at back of plate. (I do not believe this is actually supported, but it is possible. Restrictions apply.)

So the last option would be pretty cool, but you are limited by things like the height of the model, and only a single material is possible before you have to Z-hop over the front model to access the collapsible stopper to engage the filament cutter to swap the filament (which is a nightmare). If the collapsible stopper were in the back, you could print to the front of the build plate (up to a height limited by the enclosure of the machine), swap filament, print to the back of the build plate, swap filament back to the first model, continue printing on the front model (again, up to the height of the machine), cut and swap filament, and keep going on the back model. This would only necessitate a handful of filament swaps for two models of single but differing materials.

The additional benefit that this provides, beyond minimizing filament purge, is to minimize material cross-contamination in a single nozzle when using materials such as PLA as support for PETG, causing weakness in layers around support interface. By printing one model all in a single shot, swapping filament, and printing the other model, there is only one purge between models.

This could be extrapolated to optimize material swapping behavior of different models with multiple materials. Printing multiple of the same model still benefits from material changes all occurring at the same height. This feature would allow for optimization of material changes in significantly different models, and in addition to saving filament, print quality will also improve.

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Just to let you know that BBL never reads anything here. They take pride of what they did (doesn’t matter elegant or not). They won’t listen to anybody telling them what to do, because it hurts their pride.

This forum is more like a place for BBL users go here and take a p*ss instead of go ranting on other famous forums and spread the tainted name of BBL.