Water Tight Squeeze Bottle (TPU)

Tutorial for Assembly:

Back Story

My mom go to community center to swims often, and it is difficult to bring compact size body wash and shampoo along. We bought silicon container in the end but surprised by their pricing and I believe 3D printing can do better.

Objective

Currently in this version, the main objective is water tight, even under pressure. I will demonstrate below that I have achieved this.

This model is done with OpenSCAD completely customizable. If you want a smaller/bigger open diameter YOU CAN!
 

Print Specifications

• Printed with Bambu 95A TPU
• All my models was printed with A1, thus, enclosure is NOT required to print this.
• +0.15 to flow ratio
• Print + 5 degree hotter to give TPU more flow power to be able to cover crack and gaps. 
  Here is my printing temperature for Bambu 95A TPU 
  
  PLEASE DRY Filament before printing, it will 100% fail if the filament is wet.
• Please start with a small bottle for initial testing to save filament, print time, if small one leaks, bigger one will most definitely leak as well.

Documentation: Failure cases and fixes

Stringing (major lines)
 

If you see obvious thick lines of TPU stringing, this means that nearby walls are weaker (missing material) and maybe be leaking, or a weak point under pressure.

Cause: 

• The TPU is too hot and not cooling down enough.

Fix: 

• Turn temperature DOWN 5 to 10 degrees 
• if you want to same filament, print only the failed section again to see if the stringing still happens. 
  
  
  
   

Obvious Seam

How do we fix the seam in the bottle? AKA Hiding the seam.

Why hiding the seam? Good Question. The seam is a weak point for the bottle when under pressure. This is one of the first failure points. This is also prettier without seam in my opinion.

This is when the Scarf joint seam set to None
 

To fix the seam set Scarf joint seam set to Contour, 

we now have …. tiny seam!

Hidden Seam now? No problem?

:( sadly NO.

so what is the problem. Even though the print looking perfect, the TPU between layers are still not perfectly jointed. Thus, leaving tiny gaps, especially near seam position.

When under pressure these seams will get bigger, and allow water to get through.
 

How do we fix this? Great question!

We just need to ask the printer to give more filament when printing, a little overflow to fill the gaps between layers to create a truly water-tight wall.

+0.15 to the flow rate parameter within the filament profile

This value may be different for different TPU filament. May need to add more if needed.

To demonstrate, a fine-tuned TPU print profile can be watertight via FDM 3D printing. 


Me squeezing 0.5mm shell thickness bottle (single wall print)

TPU is super strong! ＾▽＾
 

If you successfully create a water-tight bottle, please consider sharing your creation in the comments with a picture of your bottle or a video. I would love to see my project has helped people!  (o^▽^o)

If you encountered any problems not listed here, or struggling to create a water-tight, leave a message down below, I will try my best to help you! (ง •̀ω•́)ง✧

Recommended Tests

TEST #1 Static water tight

It is extremely recommended to perform a water tight test by fill it with water and put a paper towel below it, leaving it over night.
Check the next morning to see if the paper towel has be wetted before

TEST #2 Squeeze Test

List for whistling noise (gas leak) and see if there is any water beads forming when the bottle is under pressure. 

I have squeezed my bottle pretty hard and it held up well even if there is slight air squeaking noise there is no water beads forming from the body. 
 

Test models I printed to do this project:

Most of the printed bottles I printed in TPU to be able to do this project… (╥﹏╥), most of them leaks or failed. 

The big one in the back was the very first bottle