A1 and AMS HT without a hub?

[Bambu-Friese]

I want to use my AMS HT exclusively for drying and printing TPU 95 filament. I don’t intend to use it as an AMS in the traditional application. After drying, I plan to use it as a single-spool holder and drying box. After printing, the filament will be manually retracted all the way out from the printer, and the end/beginning of the filament will be secured to the spool due to the rotation within the AMS HT. Only the AMS HT is connected to the A1 printer (without an AMS Lite). It looks like a external single spoolholder on the top of the A1.

According to the BBL manual, an “AMS HUB for Bambu Lab A1*” must be connected. What is the function of this hub? I only see an adaption from a 6-pin connector to a 4-pin connector.

Question: Is there any other function for the hub in my application? If no, could a cable adapter from 4-pin to 6-pin be made, with correct polarity: RS-485 +/- to RS-485 +/- and 24VDC to 24VDC? Only a single ( very) short PTFE-tube between the AMS HT* and the A1.

*) The AMS HT acts only as an external spoolholder, dryer and storage box.

[rayjay]

The A1 hub is needed for printing with an AMS/AMS 2 pro/HT because they all push filament to the printer whereas the A1 doesn’t need one for the AMS Lite as the extruder pulls the filament.

The hub is 3 things…

• a buffer to stop the pressure from the AMS getting through
• a 4 into 1 to allow multiple AMS units to be connected
• an adapter from the older 4 pin AMS connector to the newer 6 pin one.

So I guess for your use case you don’t need it.
The A1 hub is not very expensive especially compared to the P1/X1 hub.

You can get a cable on AliExpress here

I have not actually used this cable, just searched for it!

[Bambu-Friese]

You are right. But the situation to TPU Filament ist quite different. For TPU the AMS HT has a special tpu outlet. This outlet has no push-pull motor. ( sorry I forgot the right name for this gear motor ).
I think the last sentence of picture #2 ist very importend.

See more in the pictures below ( Bambu Lab AMS HT Quick Start Guide ):

[OnShape]

No you don’t need a hub and in fact can’t use a hub with tpu.

Although you might want need the hub for 4 to 6 pin conversion and feeding of stiffer material.

Note I have found the Ams HT has more drag than I was expecting using outlet from the lid.

In part because the front roller that the reel rests on is geared so you are turning those gears connected to the electric motor.

That can lead to some issues with the print head pulling the tpu.

I ended up printing a support with bearings that goes inside the Ams ht.

There is also one or two on maker world designs that use the rear roller to do the same thing,

You might consider a standalone dryer/spool holder if you don’t need the feed capability

[DMeader]

Something like the Polydryer system would do everything he wants, would be much cheaper, and wouldn’t require any electrical connection to the printer at all. Downside of the AMS HT is that it requires the printer to control the drying function.

[Bambu-Friese]

This is roughly what the final installation should look like. Then a second AMS HT will be added. One prints while the other dries simultaneously. It’s like a flip-flop.

[OnShape]

Unless you are going to use the AMS function for other materials the Ams HT might not be the right choice

for TPU only I think there are better options as already mentioned by @DMeader

You can’t read the rfid tag with tpu and there is a fair amount of drag when using that rear exit port and the spool on the rollers.

You essentially are using the Ams ht an external non Ams source.

The Ams ht is nice since it rotates the spool and can heat to 85c

[Bambu-Friese]

Thank you all for your inputs. As I said, I’m still in the testing phase and I’m still optimistic. The PTFE cable is very short, has no kinks or tight bends. And once I’ve determined the pinout of the RS-485, the 4 PIN plug to 6 PIN plug hub might also be omitted. The drive gear has two positions: engaged or disengaged. See photos:

[Bambu-Friese]

I successfully connected a 4-pin to 6-pin RS-485 cable without a hub. However, it appears this connection requires the AMS Hub A1, which is completely unavailable.