The irony is that a 3mf is an actual zip file containing all the internal files required to hold the settings, models, thumbnails and more, then renamed to have a 3mf extension.
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Yes, the irony is not lost! There are a few other file formats that are like that too⊠i.e. the âxâ version of Microsoft office files (docx vs doc).
I think itâs interesting that Bambu says you canât print 85A on an A1, yet Lost in Tech on youtube ran tests down to 83A about 5 months ago, and both the P1 and A1 were both able to print down to those hardness ratings. This video covers his testing with his caveats for printing softer TPU (below 95A).
He even tried different flow rates and gives advice on pressure advance settings. Worth looking at.
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I would honestly love to design a small litter matress for my cat, because he just loves to chew them up and it would be much easier to print them lol 
In one of his videos his most general recommendation was for a double pinch direct extruder.
Maybe, but that doesnât change the fact he was able to successfully print 83A and 85A on an A1.
BTW, I asked Lost in Tech what nozzle size he used, and his answer was 0.4 on all printers he tested.
A lot of this stuff is settings: speed, infeed setup, friction, temperature, etc. There are variables that are out of Bambuâs control. For a worry free experience they do not recommend 85A for the A1. But with (or maybe even without) a lot of tweaking it should be doable I suppose?
But even in the H2D multiple creators said that the TPU was hard to get right. An open printer like the A1 should in theory be better for a friction free infeed setup.
I always feed TPU straight from the top at work from a holder on bearings:
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Thatâs a fascinating idea. I refletch my arrows occasionally from damage, but never considered printing my own vanes. Hmm.
The commercial ones are so cheap, thereâs no financial reason to do it. But it would be interesting to try novel shapes or sizes.
Maybe Iâm missing something but why is this TPU so much more expensive then normal TPU?
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Bambu saw this post and asked me to test their new TPU and give a honest review on the forum, so here we go:
This is my HexGrips that I designed 6 years ago for my mountainbike. I will be uploading this design in the coming weeks onto MakerWorld so if you are interested please follow me over there:
https://makerworld.com/en/@Rossero/upload
But back on topic, it is these grips:
They are printed from NinjaFlex as far as I can remember and they are still going strong after all these years! Yay for TPU in general. The idea is that I get clammy hands when mountainbiking, which gets worse with gloves. So I designed grips that are âventedâ, so it cools my hands and expels moisture through the internal structure (the wonders of 3D printing), here a demo with running water:
So I got to try the new TPU and I chose the 90A because at that time I only had the A1 which supposedly doesnât print 85A. Here it is on the spool, quite roughly wound like wet noodles but it didnât give me any issues yet:
Loaded from the top:
And here during printing. I had to really contain myself to not squeeze the grips during printing 
I have to emphasize that I did not dry the filament beforehand. I was explicitly told that it had to be dried but I did not have the means to accomplish that easily and I have never dried filament in my life. Some TPUâs have given me great issues and bubblefests and some have not (like NinjaFlex which seems to stay printable). Luckily, this one seems to print really cleanly without any tweaking or advanced setup. Left is the NinjaFlex one and on the right is the Bambu 90A:
The NinjaFlex seems to have more stringing inside the hexagons but the Bambu one seems to have more stringing and roughness on the inside. I think this is largely due to the travel settings in the slicer.
The Bambu 90A is tougher than the NinjaFlex though. Here is the NinjaFlex grip when squeezing:
And here the Bambu 90A with roughly the same force:
NinjaFlex is some of the most flexible filament out there so I shouldnât be surprised, I think the 85A would be better. I am disappointed though that the 85A isnât printable on the A1 series, which seems a shame. Especially since I printed the NinjaFlex on my 7yo Dutchy3D printer with quite a simple extruder setup:
And the A1 seemed to handle the 90A with ease so I wouldnât be surprised if it could handle 85A as well.
Another issue I had is that I couldnât select the Bambu 90A filament from my A1 screen when setting up the filament. I had to select generic TPU while generic TPU is far from generic since the hardness (and therefore settings) vary wildly.
All in all I am happy with the ease with which it printed and how cleanly it went. I wish however that the A1 would be able to print softer materials than this, since the 90A is still a bit too stiff for this application. For other applications it might be the right hardness so I hope this is a somewhat helpful review and I tried to be unbiased.
Still a big fan of my grip-design after all these years though (patting myself on the back) but I would suggest the 85A if you want to print them for yourself!
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@Rossero
Seems like youâre the perfect person to ask about safe for extended skin contact. Not saying itâs not, but how does one know?
I am not the perfect person to ask about it since my evidence is purely anecdotal, but from my experience:
I have not had any issues with this material while in use. Most phone cases are TPU and people seem to be scrolling on those things for hours on end, day after day. Why I donât understand but it seems safe. (the skin contact that is)
But now I come to think of it, I get a weird hexagon shaped imprint on my palms after extended use, something I never had with my TPU phone case. Not sure what causes that.
It goes away quickly though so it never worried me.
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Those turned out great. When the extruder was doing the top layers were they swaying at all? It has so much flex you would think it would start moving with the bed.
Not that remember no. In my experience TPU suffers more from the nozzle rubbing against it than the movement of the bed. That said, this particular print (especially in NinjaFlex) is quite squishy in the squeeze direction but it doesnât really bend because it essentially is a double-walled tube. Both on the A1 print and the Dutchy print there is no discernible difference in print quality between the bottom and top of the print, and the tougher 90A improves the print stability even more. Results may vary model to model though
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After posting about how I would like to test the new TPUs from Bambulab (BBL) in my Soft Hammers Set
BBL contacted me and provided a spool to test. I opted for the 85A variant.
The filament comes in a BBL high temp spool. They provide a comprehensive How To use this new type of filaments.
The A1 Mini is not listed as compatible nor there are instructions to use with those filaments so, letâs try it with my A1 mini. 
BBL warns about the filament needs to by dried before use.
So I put it in the oven at 70ÂȘC for 8 hours as stated in the instructions.
The initial weight of the spool as taken out of the wrapper was:
1274.76 grams
After the drying it was:
1273.98 grams
so the spool lost 0.78 grams, supposedly of water. It doesnât seems too much for me.
As they warn, the spool expands with the heat from the original 67 mm wide to, in my case,
But fortunately the spool still fits my BBL Spool holder for the Multiboard:
The filament is really soft and it must be feed to the extruder as free of friction as possible, so I feed it directly to the hub, no tubing used:
The A1 mini accepted it no problem, but clearly the extrusion volume is to low. It needs some manual purges to displace the previous filament:
The original heads of the hammers were printed in AMAZON TPU 95A using the Generic TPU profile.
There is no available profile for the BBL TPU 85A for the A1 mini so I decided to use the same profile used with the AMAZON TPU. No changes.
The printer started his job no complain:
The TPU would benefit of a little more flow ratio, but it finished the job:
The unload procedure worked as expected but a little help from the user is needed pulling the filament slightly. The cut is very clear:
As soft as the filament is, it works perfectly with my clips:
In case you want to try it, this is my clip:
And speaking of softness:
This new BBL TPU 85A filament has a natural rubber touch.
An image of the original and just printed hammer heads:
You can see the under extrusion. A calibration would help with this.
Nowadays the 85A is only available in two colors: Light Cyan (the one I used) and Neon Orange (this was out of stock). Strange color options.
Comparing elasticity:
The TPU 95A for AMAZON was not affected at all from my finger pressure.
And this is the final aspect of one of my hammers, now with a dual head:
I hope that some part of this text will be useful to learn more about this new filament.
The End.
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Now I regret getting the 90A instead of the 85A for the A1 printer. Softer=better in my opinion and my grips would have benifited from the softer material, although under extrusion might be an issue in the grip design.
Neat color and write up as well!
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I found them on MakerWorld, most likely an unofficial version of it but you can have a look at it.
Great writeup! Did you change any profile settings in regards to speed and quality? Iâve been using a TPU optimized profile from MakerWorld that slows down the printing significantly but Iâm wondering if I should just try it using the default settings as well (itâs already limited by max volumetric speed anyway).
No, I always use standard settings, but I think with TPU tweaking can make a big difference. If I upload my design I will at least make the travel moves not cross perimeters, but Iâll leave the speed unchanged