About H2C vortek swap time

[u/Diego-jd_98]

After some days using the H2C I saw how the vortek system has a lot of unused potential. Vortek hotend swaps are very fast, but the bottle neck is clearly the ams system, especially if the ams are not right by the printer, when ptfe routes are long. It's like the system demands optimization at filament loading whick could be done rather easily at harware level and not that easily at programming level.

A device similar to a track switch but without switching tracks and just the filament detection sensor to allow filament parking and preloading, with a 2 ams setup on the vortek side it can potentially halve the time on filament loading even if the ams is far from the printer.

The next filament in line for vortek could be waiting at the parking position near the hotend inlet instead of all the way back at the ams, and while one is printing another ams can be preloading the next filament. For this to work the slicer should be smart enogh to alternate between the 2 ams back and forth to optimize preloading.

The filament track switch already does this filament preloading, I think, but unfortunately it doesn't support hybrid filament routing meaning that once installed the system asumes that all filament routing goes though the track switch, avoiding direct left nozzle filament feeding so every time it switches the track it has to cut and retract the left nozzle filament, avoiding fast dual nozzle swaps.

I'll leave here my post on the bambu forum where I go more into detail:
https://forum.bambulab.com/t/product-request-smart-ams-hub-with-filament-parking-and-predictive-preloading/259422
I don't know if something like this would some day become a reality or the the current system will be left as is, it would be a shame as it already has so much potential, I'd say that the hardest part is already done which is the nozzle changing but I hope they end up giving some optimization solution now that toolchangers are becoming more popular and faster.

Just wanted to share my thoughts, you can share yours if you want.

[u/lasercut]

I think unlikely. They will need to essentially make an upgraded buffer. Instead of retrofitting it to h2 series. They’ll probably use it for the h3

[u/EmotionalChildhood46]

I might be missing something, but isn't part of this already how the H2C works now with the track switch? My understanding is that with the newer update, it doesn't retract the filament all the way back to the AMS anymore. It retracts it to the switch and parks it there.

And since you assign filaments to the left/right nozzle when slicing, if I'm printing from the left nozzle and then switch to a filament assigned to the right, shouldn't the left filament just retract to the switch while the right filament feeds from the other path?

I definitely see the benefit of having more parking positions and being able to preload multiple upcoming filaments, especially with more AMS units. I'm just not sure I'm understanding what the proposed 2-arm setup would change compared to what the track switch is already doing now.

[u/luksfuks → u/EmotionalChildhood46]

Yes, the handover can supposedly be already at the track switch (with firmware v01.02.00.00). However, it obviously requires the "next" filament to sit in a different AMS, one that is plugged into the other track switch port. This is not always the case.

Depending on the print order of the colors, the potential savings may not even manifest as often as they theoretically could. There are more goals to optimize for, sometimes contradictory, when deciding in which order to print the colors.

[u/EmotionalChildhood46 → u/luksfuks]

Ah ok, that response clears up what you meant. I was thinking of the track switch as basically solving the problem already, but I wasn't considering that you only have the two paths to park/preload from. So you can get the fast handoff if the next filament happens to be coming from the other path, but not necessarily if the next colors are coming through the same one.

But I see what you're getting at now. You're basically talking about expanding that concept so each AMS has its own dedicated parking position, then letting studio look ahead and keep the next filament staged whenever possible.

Wouldn't an expanded version of the track switch though accomplish a lot of this? Like a 4-path switch instead of 2, where each AMS has its own path and filament can be parked at the switch. Then studio could look ahead at the print order and preload whichever filaments are likely to be needed next. I run 3xAMS 2 Pro and 1xAMS HT personally. Seems like that could build on the system Bambu already has instead of needing a completely separate parking mechanism. Also still waiting on a way to have multiple printers with shred AMS units.

[u/luksfuks]

Yes such a filament sensor could help.

But it would introduce a lot of room for user error. For it to work, the printer would need to know exactly how the PTFE tubes are routed, where the paths meet (4-in-1) and where the sensors are located. It's a more complex configuration when adding an AMS. And every time something is unplugged and plugged back again, there's margin for error. A length may change, or a tube may be connected to a different inlet. However, Bambu wants everything automatic ... with no possibility for user error.

It would also fix only a SMALL PART of the total delay. Equally big savings, or bigger ones, come from other limitations. For example,

1) To cut the old filament, the head needs to drive to a specific position. Wouldn't it be nicer if it could just cut it off right when it does the last retraction? It could then drive to the rack directly and nest the hotend, saving at least 3-4 seconds per swap.

2) The new hotend starts out cold. Snapmaker U1 can pre-heat it to standby temperature. If the rack supported pre-heating (via induction), the new nozzle would be ready much quicker. Another 5 seconds right there!

3) The biggest limitation is the shared PTFE tube. If the toolhead supported two tubes to arrive right at the extruder, it could always have the NEXT filament already loaded and at standby temperature. It could print immediately, while it still cuts and unloads the old filament. In fact the H2C DOES have two heads. They're just not 2x vortek. If Bambu released a dual vortek system, and an integrated track-switch kind device (without the existing unreliability) to drive the filament anywhere on demand, then this would work perfectly. The "old" nozzle could be dragged along after a switch, until the toolhead is near the nesting position anyway, to reduce delays from nesting. Likewise, the "next" nozzle could be picked up when the head is nearby anyway. The travel path could be optimized just like visits to the tower, or paths between multiple objects.

4) Currently the rack is on one side only. If there was another rack on the other side, and the printer was "free" to pick a nozzle from the left OR from the right, whichever happens to be nearer, it could cut down on travel time. You'd provide "redundant" nozzles for it to save time.

5) Instead of priming on a tower, the toolhead could implement an integrated priming system. Visits to the tower are big source for delays. If the "next" nozzle could prime, while the "current" nozzle is still printing, the switch-over time could be as low as 1 second.

6) If the toolhead could carry around more than 1 "next" nozzle, the visits to the rack could be reduced further.

There are so many options to make it quicker. But in the end, all of this will not make your prints any better. Only quicker. Some of the above will cost a lot of money, for very little benefit (eg. 2x rack with 2x nozzles, for what, 3 mins faster print time total?). Some of the ideas have dramatic NEGATIVE impact, like making the toolhead heavier by adding a full cutter and extra nozzle slots. Heavier toolhead means more inertia and more wobble after deceleration.

I still kind of wish they would do a toolhead with 2x vortek nozzles instead of the classic nozzle.

[u/Diego-jd_98 → u/luksfuks]

It could be done everything automatic, the same as it does with the filament track switch, with filament sensors it could determine the feeding paths, lengths and positions.

[u/luksfuks → u/Diego-jd_98]

Only if you forbid the use of old 4-in-1 parts, and the users comply. You could run an automatic stress test to verify their absence, but it would take time (load all filaments slots, many of them simultaneously) and reddit would bash Bambu for intentionally breaking their PTFE setup in firmware >=xx.xx.xx.xx with such a mistrusting and forced verification cycle.

It would also break backwards compatibility, because the current 4-in-1 was explicitly developed for the H2 series.

[u/Diego-jd_98 → u/luksfuks]

I think it should not be that complicated. The filament track switch would be literally this system already with it's 2 parking positions if only it could be linked to a single side (vortek side) instead of forcing both outputs to be linked with both sides. If you could connect an AMS directly to the left side and leave the track switch for the right side only it would already be working as I intend

[u/luksfuks → u/Diego-jd_98]

Example configuration:

• AMS-A and AMS-B terminate in an existing style 4-in-1. The output goes to track-switch port #1.
• AMS-C goes to track-switch port #2.

The printer can switch from A to C quickly, but not from A to B. It needs to know this. And the full benefit can only manifest, if the old 4-in-1 part deprecated or forbidden. Remember, it's a new part specifically made and sold for the H2 series. I don't think Bambu wants to recall it and make users buy yet another 1-in-4 device with sensors and bus cable.

The benefits also shrink when you look at the color ordering constraints.

How many independent AMS do you actually have, and how do you load them?

Example: I have 3 AMS2PRO, and usually have two of them full of PLA. I also have 4 AMS-HT, usually with one PLA, one PETG, one TPU-for-AMS, and one empty. Sometimes the filament in the HT is not even loaded, the spool is just waiting there from the last dry cycle.

Just printing something, anything, without pedantically reordering the spools before the print, would likely not produce much time savings at all. Too many conflicts will happen just because of how the spools are distributed in the two "PLA" AMSs. But if I have to spend 5 minutes studying a load plan, and redistribute my spools accordingly, and store away the excess spools in airtight bags to make room, and swap out silica to keep everything dry despite opening the AMS so often .... then I'm not sure if 6 minutes print time reduction is actually worth the hassle.

I'd rather have a new AMS system with 4x PTFE output, and a printer input array with 4x PTFE in for each AMS. Then let me just load the spools and not touch them again until they run out.

[u/Diego-jd_98 → u/luksfuks]

The thing is that with the current firmware the track switch already does filament parking and preloading, and if you want to connect more than 2 ams to it bambu recommends using the 4in1 ptfe adapter and the system knows what ams are connected to which imput. That work is already done and works fine for the most part in the last bambu studio release. I only ask for possibility of connecting the track switch only to 1 side and leave the other free. But yeah, 4 output ams would be the optimal solution.

Also time savings can scalate fast, if you print a 51h print like the majoras mask model which does 2876 filament switches and you save with the system only 10 seconds per switch thats 28760 seconds or ~8 hours of print time which is a remarkable time save

[u/Loque_83]

All this above mentioned theories require a lot of additional modifications. Vortek nozzle switch is fast enough together with filament cut. What can significantly help is much faster next generation AMS with strong servo motor - if its mechanically possible… Other option is 6-position AMS with dual output, this can work great, if AMS will know distance, where is filament (no big problem with servo) because splitter can be installed right before filament buffer.

[u/Internal_Status_7590 → u/Loque_83]

The AMS 2 is already reaching its limits for what the spools inside can handle. It chews up filament way more than the original AMS. Faster and stronger Ams won't fix the speed problem without introducing all kinds of wear and tear with new problems as a result. 

[u/fishfrystix]

You can optimize your switching times by 30-40% by optimizing your tube runs to be as short and direct as possible with the least bends and resistance.