Recommended TPU 95A HF print settings?

hagmonk · November 19, 2023, 6:54am

Just got my delivery of TPU 95A HF. I noticed there are no filament profiles for this yet. Loaded it up on the A1 mini and set the max volumetric speed to 12 mm^3/s, no other changes. Not a particularly good result, obviously there’s more to it than this

Filament was dried for four hours, and spooled directly from the filament dryer, 0.4mm nozzle, 0.16mm layer height, not much else to say aside from that.

Obviously I could start troubleshooting the filament and figure out what is going on, but I figure it’s worth waiting for the filament profiles to be available as a starting point. For reference I’m on the 1.8.0.57 beta version of Bambu Studio.

Electro · November 21, 2023, 1:59am

Have you tried turning it off and then on again?

Seriously though, yikes!

Did you tell the slicer that it was generic TPU? At the very least I’d say it looks like it was printed too quickly for it’s own good.

Level23 · November 21, 2023, 2:07am

Looks like my first few attempts using regular TPU when I first started messing with the profiles. Yes, a bit more info might help. Was this definitely the default generic profile or was there any tweaking? It seems like a sad little benchy at the moment…

hagmonk · November 21, 2023, 10:59pm

maurice-moss-unexpected-reboot

I started with the regular Bambu TPU profile and simply upped the flow rate to 12 mm^3/s (per their claim the HF stuff can be printed at that speed). Since it came out so bad, I basically just laughed and decided I’d wait until they publish an official profile and then try to debug what is going on.

I’ve honestly had zero issues with both generic and Bambu TPU in the past. Their profiles for those are great. Folks seem to struggle a lot with TPU but I’m fairly religious about drying and storing it properly, and have reliably great results. Hence my feeling there’s something more than just ramping up the volumetric flow rate.

hagmonk · November 21, 2023, 11:07pm

I have two X1C printers but they’re busy doing other stuff. Otherwise I’d try the lidar based calibrations which I’ve found to be very reliable at dialing out flow rate problems when you have some filament that might not be as dry as you think it could be, or for dialing in generic filament. I’ve used this process for some Sainsmart TPU and had great results.

To demonstrate TPU normally works great for me, here’s something I printed with Bambu and Sainsmart TPU last month. My local barbershop goes all-in on halloween decorations, so I decided to print them a shoebox full of TPU spiders, which absolutely blew their mind. The stringing you can’t avoid with TPU ends up being a feature rather than a bug when you’re printing spiders (banana for scale)

However this print took a rather long time, I want to say about 6 hrs per tray of spiders. Doing this at 12mm^3/s is extremely appealing which is why I’m keen to get their official profile for the new TPU HF!

Level23 · November 22, 2023, 1:27am

@hagmonk, I’ve printed a good bit with TPU 95A (different brands) and one thing I have noted as compared to the HF variety is that the HF stuff is a bit more stiff. My thinking is that TPU-HF might be blended with PLA to get that high flow characteristic. Maybe that’s not the correct material, but keeping in mind that ‘high flow’ attribute makes me wonder if treating it a bit more like PLA will improve your print. Just pondering here🤔

Level23 · November 22, 2023, 1:28am

Love the spider idea by the way. Quite creative with the stringing!

SJ_3Designs · November 22, 2023, 1:57am

I use the basic TPU profile and change the Retraction settings to a Length of 1mm and a Z hop when retracting to 0 mm. This has helped with stringing a bunch. Now specifically for the HF Bambu filament I have been testing it and found using 6 mm^3/s for the volumetric flow has helped a lot. Most of the other TPU I print (mainly Sainsmart) I use a volumetric flow of 2.6 mm^3/s to get good results. So I’m a little more than double with the HF which is nice but I would love to know how to get the 12 mm^3/s that Bambu states for it.

hagmonk · November 26, 2023, 8:46pm

So I noticed the TPU HF settings are now available in the latest beta. And guess what … the only change is the maximum volumetric speed I diff’d the JSON filament profiles just to be sure:

> jsondiff  Bambu\ TPU\ 95A\ \@base.json Bambu\ TPU\ 95A\ HF\ \@base.json  | jq
[
  {
    "op": "add",
    "path": "/filament_max_volumetric_speed",
    "value": [
      "12"
    ]
  },
  {
    "op": "replace",
    "path": "/filament_id",
    "value": "GFU00"
  },
  {
    "op": "replace",
    "path": "/name",
    "value": "Bambu TPU 95A HF @base"
  }
]

Currently doing a test print after drying overnight for 8+ hours. Last time I do admit I was a bit skimpy on the drying. My experience has been that I can get away with a four hour dry straight out of the silver bag – apparently not so this time! That first print came out looking like a total booger.

Here’s an interesting observation, before I could even get a print even starting to work: I had a ton of trouble getting the extruder to take a good grip on the filament! I ended up cleaning the 0.4mm nozzle with several cold pulls to make sure that was free of debris, then manually extruding and feeding the filament by hand until I could let go and see the extruder able to pull the spool by itself. It seriously took half a dozen tries. I have not experienced that with TPU on the X1C. It could be a foible of TPU on the A1M? Thought I would mention it in case anyone else struggles.

Pictures of the HF result forthcoming now that I have filament being laid down.

hagmonk · November 26, 2023, 9:58pm

Ok, well, definitely not the best benchie or even TPU benchie I’ve printed. But an improvement over last time! I think I need to load this filament up in the X1C and do flow calibration because I’m really changing two variables at once here, the type of TPU and the printer I’m using.

The hull lines on the bow are a total mess. Again I’ve done zero tuning here, I’m not expecting absolute perfection without tweaking, more just trying to get a sense on whether the “HF” in this filament is a free lunch. Per @SJ_3Designs I’ll also try 6mm^3/s and see how that flies.

Level23 · November 26, 2023, 10:36pm

How is the adhesion with the HF by the way? What plate are you using?

hagmonk · November 27, 2023, 12:37am

Adhesion seems fine! If you can get the filament to actually extrude! Using the Bambu high temp PEI on the A1M and a bit of glue stick. The latest beta of Bambu Studio is also a bit more intelligent about model rotation; it positions the benchie such that the long axis is aligned with the bed movement, which will help adhesion in general.

I’m currently printing this TPU wallet using TPU HF in the X1C. I tried printing it on the A1M – same filament, nozzle size, etc – and immediately got a pile of spaghetti. The X1C on the other hand looks like it will complete perfectly fine (in about 50% of the time compared to the regular TPU profile from the maker). I think I’m done with experimenting with TPU HF on the A1M for now. Maybe I’m missing something really obvious??

Also of note: the X1C also successfully performed flow rate calibration on the filament, setting a value of 0.946 as compared to 1.0 in the default TPU HF profile. Turns out you can’t do flow dynamics calibration with TPU so I had to skip that one.

In the X1C I’m trying out (for the first time – so much for isolating variables) the Lightyear G10 Pro build plate. Not using any adhesive on that one and it’s holding up like a champ. In fact TPU seems to stick to it a little too well. I figured I’d give that a try since it’s an extremely thick build plate and this model has a precariously thin footprint.

WishingTree · November 30, 2023, 1:15am

Any more luck with getting your profile proper? Did you just build it off the Bambu 95A premade profile? … im frustrated cause im not having much luck finding a profile thatll work right for this material

d_p · November 30, 2023, 2:02am

I am also looking for a print profile for this material. It was so expensive and seeing these photos have me scared to even try and waste any!

lkraus · November 30, 2023, 3:10am

As mentioned earlier by @hagmonk, Bambu added their profile for TPU 95A HF to the most recent beta release of Studio.

Get it at Release 1.8.0 Public beta 2 · bambulab/BambuStudio · GitHub.

Electro · November 30, 2023, 7:50am

I tried some high speed TPU today. I set speeds to within the range of 50-90. It worked fine until there was too much tension on the spool holder I was using, and then it started skipping steps. The only way I could get it to work was to keep pulling out more filament by hand to give it enough slack.

I printed on the engineering sheet with a little bit of hair spray (not sure if that was needed or not, but it worked well as far as hold and release when needed).

Now I am trying to figure out how to set up something so that I don’t have to be there to keep feeding the filament enough slack.

lkraus · November 30, 2023, 12:30pm

I had this side mount in place before I tried TPU. Even with the slightly longer feed tube, I never had a feed problem. I suspect any of the spool holders using bearings to reduce drag would work.

Level23 · November 30, 2023, 3:59pm

@electro, I designed a turntable that you could 3D print and use to help reduce friction. Here is a link:
https://grabcad.com/library/3d-printer-filament-turntable-1

It does require a bearing which I list in the details and you can pick up at an auto store. It’s a starting point at least.

hagmonk · December 4, 2023, 10:23pm

Update: very interesting finding. Remember I said earlier I had trouble getting the extruder to grab the filament properly on the A1M? This entire time I’ve been testing with the same roll of red TPU 95A HF …

Well, I switched over to the X1C and loaded the spool of red TPU 95A HF. Got the same problematic prints. Dialed the volumetric flow rate down to 6mm^3/s. Same issues. Hmm. I was feeding the filament directly from a Sunlu S2 set to TPU. It has been dried thoroughly. What gives …

Then I noticed something funny. I should have snagged a photo, but I had this feeling that the diameter of the red filament didn’t seem to be 1.75mm. Sure enough I checked with calipers and it was closer to 1.6mm. Crazy! I trimmed a meter or so off the spool – now we’re back to 1.75. So … it was being stretched!

This was somewhat unexpected since I got consistently bad prints from the red filament in the following positions:

Eibos cyclopes drier + A1M (didn’t check for stretching)
A1M spool holder + A1M (didn’t check for stretching)
Sunlu drier + X1C (discovered the stretching)
X1C spool holder + X1C (still being stretched)

My suspicions now shifted to the filament itself. I opened up a roll of the black TPU 95A HF, dried it for 8 hours, and tried a print starting at 6mm^3/s, feeding it from the Sunlu drier into the X1C. Here’s the result:

That is a completely passable TPU benchie. Yeah there are some areas it could be tidied up. But I’ll take it given it came out in ~50m which is obviously much faster than normal!

So what can we infer from this? I honestly don’t really know. I mean I can guess but I’d just be guessing. I feel as if it’s safe to assume this roll is a dud. Does anyone happen to know how I can arrange for a Bambu employee to eyeball this thread and perhaps offer suggestions? I’m happy to conduct further experiments. Maybe they’d like to capture it and figure out if they added too much baking soda to the mix?

hagmonk · December 4, 2023, 10:47pm

This is really cool! I have recently been struggling to design a “sled” for the AMS, so I can stack them with minimal clearance and slide the bottom one forward and backwards. It incorporates some bearings and this is the first time I’ve worked with them. I had this notion that I’d be able to press the bearings in a kind of snap-fit way … it’s really not working at all, lol. I think I’m going to have to print an axle and press that assembly in instead. Thought I’d ask your opinion because you’ve clearly designed parts with bearings successfully!