F2 Spool Holder for "TPU Temu/Aliexpress" Box

F2 (read: Friction Free) Spool Holder for "TPU Temu/Aliexpress Cereal" Box

TL;DR:  F2 SpoolHolder is designed (mainly) for printing TPU from an airtight "Cereal" box purchased on Temu/Aliexpress. It provides the least possible resistance when unwinding the filament and eliminates printing errors (especially underextrusion).

More detailed description: 

I needed an airtight box for printing TPU, so I bought one from Temu (it even included a simple spool holder). The box itself is quite OK, but the holder is unusable. Even though it is equipped with bearings, it has too much resistance/friction - so the printer's extruder cannot pull the flexible filament smoothly - resulting in printing errors, underextrusion, poor quality result .. name it.

So I designed my own Spool Holder with as little resistance as possible (or rather "…as little as I could manage"). Frankly, the resulting model is somewhat "overengineered" (I'm a "CAD noob" and I enjoy playing around with the design more than is practical :-) But I'm happy with the result and how it works. You may be also interested if:

• you need a similar Spool Holder for TPU printing … of course, it will also work for other types of filament
• you have the same/similar "China" box … of course, you can use it as "standalone" holder without any box

My F2Spool Holder model is now available to you - Enjoy !!! 

If you decide to print and use it, please read the information below so that it serves you as well as possible:

Temu/Aliexpress Airtight Box 

The holder was designed for this box (https://www.temu.com/goods.html?_bg_fs=1&goods_id=601102932690756), but it can also work for others if they are basically the same size. Definitely, F2 Spool Holder can, of course, be used "standalone", without any box.

Material -  PLA is perfectly sufficient for this model. Personally, I used PLA Tough.

Hardware

You will need 2pcs "skate" bearings to complete the assembly, and if you also use a "Filament Guide" feature (more information below), you will need two more bearings of the same type. So 4pcs total.

Bearings - these are standard "skate" type bearings (22mm OD, 8mm ID, 7mm wide) you can find anywhere. However, these bearings come in different qualities, which significantly differ in terms of "smoothness of operation".  Some rotate "so-so," while others "literally fly." The better the quality, the better the axle holder/Spool will rotate, and the better everything will work. If you can, invest in high-quality bearings (ceramic hybrid) – you will get the best possible performance from F2 Spool Holder.

• TIP:  if you only have the basic "so-so" ones, you can "bathing" them thoroughly in IPA (isopropyl alcohol) before use - this will loosen any thick lubricant inside. Then run them manually as best you can (you may need to try several bearings – some simply cannot be freed properly.) Finally lubricate them with WD40 - if you are lucky, the bearings will then run significantly better.
  
  FYI – with the help of IPA and WD40, I managed to get the "so-so" bearings working so great, that the spool spins for more than a minute !!!! 
  When using higher quality ceramic hybrid bearings, you can expect even more impressive results …

Assembly 

it is simple and should be clear from the following picture.
 

Spool Carrier & Adapters

Consists of a threaded Axle and two Adapters attaching the spool. The diameter of the adapters have to correspond to the specific spool you use - its inner diameter.  Note, different manufacturers and types of filaments use spools with different inner diameters.

• Important - Adapters are NOT part of the main profile - to complete the model, you need also download the Print Profile "F2 Spool Holder Adapters", which contains all available adapters - designed for the most commonly used spool diameters:  
  • all sizes from 50mm to 58mm in 1mm step
  • 63mm
  • 73mm

  • 75mm 

    
    (Why separate profile? It allows for future updates and additions without having to change the main print profile of the model).
     

Of course, you only print the adapter/size you need (according to the spools you use) - you need 2 pieces (they are the same). For adapter size, refer its name (includes the dimensions) and the same info is also embossed on the body of the Adapter.
 

If, for any reason, you need a size that is not in the standard offer, you can use "Spacers", which are small plugs that slide into the cutout in the adapter and increase its size - they are available in sizes 1, 2, 3, and 4 mm. In addition, two "Wedge shaped" spacers are available, which allow you to change the diameter of the adapter "steplessly".

Spacers can be also useful if you need to use a larger spool than you normally have on a one-time basis (you don't have to print the entire adapter just for one use).

IMPORTANT: Attach the Spool using adapters to the axle so that it is well centered and ensures smooth operation.

Filament Guide (optional feature) 

Temu/Aliexpress Boxes are equipped with two outpt "ports" (predrilled holes) to feed filament out of the box. I use the front/side one. However, the spool can be either very full or almost empty, and the filament can come out of the spool from the left, right ...  so it rarely goes perfectly straight into the output hole. It usually comes out at an angle, which unnecessarily increases friction and resistance for the printer extruder.

That's why I added a "Filament Guide" that aligns the filament from the spool to an ideal plane. The passage through the exit hole is then without unnecessary bends, resistance, and friction.

The question may arise as to how useful the Filament Guide really is, but it proved itself during my testing. What's more, it is designed to be optional – if you consider it unnecessary, there is no need to print it, and you can use the F2SpoolHolder without it (then use two small "blinding plugs" from Plate1 to cover unused mounting slots in the base)

Silica Container 

When printing from a closed box, the Silica Container will come in handy. It is an optional part - not connected to model's base (it is only inserted). If you use F2 SpoolHolder outside the closed box only, you do not have to print./use it.

Hygrometer 

F2 SpoolHolder is equipped with a simple holder for the most commonly used moisture meter (square shape). There's nothing amazing to see here :-)

Print Profile

I recommend using the original Print Profile (it contains all the settings necessary for successful printing). If, for some reason, you decide to create your own, then pay attention to these details:

• FilamentGuide Axle is printed with a layer height of 1.2 and variable layer height, with the smallest possible 0.08 set for the "rounded" filament inlet. The axle is intentionally printed on its side so that the rounded inlet is at the top to be printed as perfectly and smoothly as possible.
   
• Silica Box Lid - contains a Modifier with the following parameters: Walls:0, TopShellLayers:0, BottomShellLayers:0, SparseInfillDens: 28%, and SparseInfillPattern: Honeycomb to create “holes pattern”.
   
• Carrier/Adapter Axle - is intentionally printed "upright" and requires little support. Set Top Z distance to 2.5 for easy removal of support
   
• The Adapters have intentionally disabled support—otherwise, the slicer tends to put some support at the beginning of the thread, which is unnecessary and detrimental.

I believe that everything important has been said. All that remains is to wish you - Enjoy!

BTW: The license is set as a Standard Digital File License, which does not allow modifications, remixes, etc. However, if you have a good idea on how to improve F2SpoolHolder, please contact me. If it is something meaningful (not adding just Bambu logo), I will be happy to make an exception …