Hi, did anyone experience any problem using the H2D TPU inlet with TPU90 instead of opening the top glass cover and directly feeding the filament? I ordered TPU90 and just want to make sure. I am intending to follow the guide in the first part of this video:
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I have been printing 85A through the bypass port. You need to make sure your path is smooth.
The top feed is the most optimal though.
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I printed down to 65A through that port and through PTFE tubes from an AMS HT, as @Gerrit says, you need to check the paths to be as smooth as possible.
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I print a lot of 90A from external spool via the bypass port without issues.
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Same here I print 90A all the time through the bypass port. I’ve been wanting to try 85A so seeing @gerrit’s comment has me convinced I should on my next 85A print. Thanks!
I used it with eSun 85e a lots of times without any problems.
I put a third PTFE tube direct to the right nozzle
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This is the best way through the bypass. Use of minimal PTFE tube lowers resistance.
I’m currently printing Siraya Tech PEBA Air through the AMS HT (while drying) via the bypass port and PTFE tubes with absolutely zero issues.
The only hiccup was my own fault—I forgot to check that the spool could rotate freely. Pro tip: if you seat the spool slightly skewed in the AMS, it won’t turn properly! 
Side note: If you’re choosing between TPU and PEBA, I’d pick PEBA every time. It’s significantly more durable than TPU, and if you want that bounce/rebound effect, PEBA is absolutely fantastic material.
Another thing in the TPU vs PEBA war 
Side note: If you’re choosing between TPU and PEBA, here’s what the data actually shows:
PEBA (Polyether Block Amide) - Verified advantages:
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Superior rebound/energy return: 70-85% rebound elasticity vs TPU’s 45-55%
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Significantly lighter: ~1.0 g/cm³ vs TPU’s 1.20-1.25 g/cm³ (15-20% weight reduction)
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Better low-temperature performance: Maintains flexibility down to -60°C
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Higher tensile stress at elongation: Requires more force to stretch at 100%, 200%, and 300% elongation compared to equivalent Shore hardness TPU
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Superior compression set resistance: Maintains shape memory better over time - resists permanent deformation under sustained load
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Exceptional impact resistance: Withstands high-speed impacts that would damage TPU; combat robotics tests show it endures direct blade strikes with only surface scarring
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Outstanding fatigue resistance: Maintains properties through repeated bending/stretching cycles without degradation
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Faster potential print speeds: Can print 2x faster than TPU when properly tuned (120 mm/s vs 55 mm/s)
TPU (Thermoplastic Polyurethane) - Verified advantages:
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Wider commercial availability: Much broader selection of brands, colors, and Shore hardness options
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Better sliding wear resistance: Superior abrasion resistance in continuous sliding contact applications (maintains <300 mm³ abrasion loss vs PEBA’s 400+ mm³)
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Lower cost: Typically less expensive per kg
Shore Hardness Ranges:
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PEBA: Available from 60A-95A
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TPU: Available from 60A-98A
Weight comparison example (same print settings):
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TPU 95A: 88g
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PEBA 95A: 67g (~24% lighter)
My practical experience: For applications requiring elastic rebound combined with impact durability and fatigue resistance, PEBA outperforms TPU significantly. The weight savings and bounce characteristics are immediately apparent in functional parts. However, for applications with continuous sliding wear (like conveyor parts or rollers), TPU’s superior sliding abrasion resistance makes it the better choice.
Do you guys use any retraction when printing TPU? The Polymaker TPU90 settings in the wiki for X1C had retraction of 0.8mm length with 30 mm/s speed so every time I tried to print I used those.