I’ve been experiencing some issues with my AMS where I couldn’t get my lovely filament to my beautifully engineered printer. It turns out that I was using some tubes that were slightly too narrow. The AMS mechanism is very sensitive.
The filament met too much resistance and that caused the failsafe mechanisms to kick in.
I compared the tubes I was using with the OEM tubes and once I switched over to the OEM tubes everything worked like a charm.
If you are replacing your tubes I would strongly recommend going with the tried and true replacement parts. If you go with another brand- venture at your own risk.
While I realize you’re trying to be helpful, this is not sound advice and borders on chicken-littlism. It only serves to create fear, uncertainty, and doubt for new users and could intimidate them from exploring non-vendor solutions. It sounds like you purchased the incorrect ID and OD if you were having trouble.
The risk you outline is vastly overstated if one understands how to purchase to spec. This creates a false notion that only Bambu has the “secret sauce” when it comes to spare parts. I assure you, the opposite is true. There is nothing special about their PTFE tubes that a small amount of educated buying can’t address. PTFE is PTFE—its chemistry doesn’t change with the supplier. This whole hobby is based on a DIY spirit of figuring things out ourselves. Bambu provides the relevant specs in their store. For example, here is the spec for the PTFE tubes:
That said, for the amount of tubing you’d use under normal circumstances, Bambu’s prices are low enough that the convenience of pre-cut pieces can be worth it—especially if you’re already meeting their free shipping minimum. Personally, I took both routes and now have a 25ft spool I cut to size. Compared to Bambu’s precut tubes, there was NO difference. I needed variable lengths to build dry boxes and wanted a single standard size of PTFE tube on hand for convenience.
I think you can get some significant resistance by cutting the tube using nippers or other “crushing” type cutter. You really need one of the PTFE cutters that delivers a cut without crushing the ends.
However, I have been using “alternative” PTFE (Capricorn and generic) with ID 2mm x OD 4mm instead of the official ID 2.5mm × OD 4mm quite successfully on the AMS and AMS2 Pro.
I needed longer PTFE as my AMS placement was not optimal so I reused what I had whilst waiting for Amazon to deliver.
As others have stated though, use a proper 90 Degree flush cutting tool or blade.
Additionally, use a large (and sharp) drill bit to chamfer the ends (like a funnel) as this will assist in centering the filament when it enters the tube from the feeding mechanism. (I do both ends so that I do not have to take note which side in “in” and which side is “out” when disassembling.
It also does not hurt to ensure that the filament is flush-cut when feeding it into the AMS feeder for the first time.
Although, if you are ordering PTFE you might as well order the spec stuff: ID 2.5mm x OD 4mm. I still chamfer though.
You could also have a piece of filament in the PTFE tube when cutting to keep it from deforming to much and I use a pliers to slightly reshape the cut to round it out.
this ate up a lot of time for me and my other tubes matched those specs