What spool load do you use for TPU?

Bambu Lab H2 Series
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I have found the most reliable way to print 80A tpu is to carefully unspool it to minimise resistance when the extruder is pulling it in.

If i dont do this it just stretches then doesnt feed.

Not ideal.

I havent tried printing a holder & feeding from above with the top cover off yet, because the main issue seems to be the inertia of the 1kg spool itself and having the spool above wont help that.

Im thinking that reducing the weight by only having a few hundred grams on the spool will help with this…

Does anyone print tpu < 90A successfully with a 1kg spool?

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Read the Bambu Lab wiki guide that takes you through what you need to do and hue.

There is also a model you can print to make soft TPU printing far easier.

https://wiki.bambulab.com/en/filament/tpu

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3

I strongly suggest building a top mount spool holder, remove the right side PTFE tube, insert a short 4-5cm PTFE tube instead and feed the TPU from above directly to the head.

See this model:

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4

Thanks, that article specifically mentions spool resistence, which seems to be my issue. I guess Ill have to do a top mounted holder, or the side mount but I still need less resistence…thanks.

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5

Hi,

We have printed TPU 95A by just placing a plate on top of the printer. Later on I created the frame in the link I shared.

Do remember that the frame is intended to be placed instead of the glass top.

Dry your TPU properly. WE have an oven for that but also Polydrier … I fed the TPU from the Polydrier to printer head while the driyer was active…

6

I have described this in several posts on the forum already, but here is the short version again.

On my H2D and X1 Carbon, I run TPU down to 65A directly from my AMS HT, through the AMS HT bypass and PTFE tubing to the bypass on the H2D, or directly behind the buffer on the X1 Carbon and then via PTFE to the extruder. I keep my TPU and PEBA in the AMS HT so I can dry and print at the same time, which works flawlessly for me. However, I have replaced all PTFE tubes with PTFE Tough, which in my tests gave the lowest friction, and I have also modified all my AMS HT units so that the spools roll completely freely, since none of my four AMS HTs did that out of the box.

This setup is clearly outside the official recommendations in the Wiki, but it works very well in my environment. If you are inexperienced, this is not something I would recommend, as it can easily lead to feeding issues.

I have my AMS HT units positioned on top of the printer. If you have them placed on top of the printer as well, be aware that there is considerable heat transfer from the printer to the AMS HT units above, which can cause filaments like PLA to soften and create problems if they are loaded while you are printing high-temperature materials. I learned this the hard way!

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What type of modifications did you do to your AMS HT @L0rdS474n ?

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Not really a modification per se. I disassembled the entire AMS HT and ensured the rollers weren’t binding or rotating sluggishly. For some reason, all the AMS HT units I’ve purchased have had sluggish rollers out of the box. If you want to reliably print TPU in these units, you must ensure the rollers rotate with absolutely no resistance.

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