Tubing Bulkhead / Panel Fitting - Parametric

Note that there is now a second version of this design. That one requires no hardware, but is a little more bulky and probably a little less robust than this one.

Wanted to make a brake bleed container for my car and realized I could just about as easily model a generic hose fitting. These adapters allow a tube to be run through the wall (or cap) of a container. Mounts with through-bolts to mitigate layer adhesion concerns. Tubing is compressed by small rings of material to clamp it in place and provide strain relief. Vented and unvented versions are included (sealant will be required if you want to prevent leaks for the unvented one). A drilling template is also provided.

All required supports are built-in via bridging. After printing, just twist the two halves apart and trim the bridging filament pieces.

To install:

1) Use the drilling template to drill centering holes in the container or cap. Center hole is for the tubing to pass through. The outer radial holes are for the bolts and vent holes (if desired, if not vented just drill one set of opposed outer holes).

2) Fit the two adapter halves and make sure the bolts will insert all through way through them, then remove the bolts. If too tight, either drill them out to the proper size or change the hole size parameter and reprint.

3) take the two adapter halves and put them around the tubing, leaving the desired amount of length on both sides. and squeeze them together with a vise or pliers. insert the bolts to hold the halves together.

4) Add sealant if making an unvented connection and a seal matters.

5) Feed the tubing through the center hole you drilled in the container or cap, and insert the bolts through the bolt holes (vent holes, if you drilled them are in the same radial position as the bolt ones, so any opposite pair will do). Then add your washers and nuts and tighten.

You can create your own adapter with any dimensions you want in this Onshape document. No account is required. The default values are for ¼" ID, 3/8" OD tubing, meant to be installed in a soda bottle cap with M2 20mm bolts. This is the model that is included in this listing, as Printables requires one.
 

The adjustable parameters (in the upper left of the Onshape page; you may have to scroll or expand this section to see them all) are:

Height: The height of the adapter, adjust to fit your bolts, nuts, washers, and container wall thickness.

Outer Diam: The outside diameter of the adapter.

Screw Hole Diam: The diameter of hole for the bolts. try to keep this snug for better support, as the bolts keep the tubing compressed.

Tube Diam: The uncompressed outside diameter of the tubing the adapter is for.

Compress Dist: The amount to compress the tubing in the overall adapter .

Ring Compress Dist: The amount the holding rings should compress the tubing (this is in absolute terms from the uncompressed tubing size, not on top of the previous parameter). Must be ≥ the Compress Dist parameter.

Vertical Clearance: How much space to add between the the halves vertically.

Horizontal Clearance: How much space to add between the the halves horizontally.

Template Diam: Outer diameter of the drilling template. This part has centering holes for the screws, vents (if needed), and tubing clearance hole.

Layer Height: Height the model will be printed at. Used to determine the thickness of the bridges.

Once you've set all the parameters, right-click on the models you need (lower left), choose “export” and select the download format (most people will want “stl”), and finally hit the second “export” button.