What to measure
Twelve millimetres is one of the standard outside diameters for metric copper tube, seen more often in continental Europe than in the United Kingdom, where 10 and 15 mm are the usual small sizes. It is also a common size for nylon and polyurethane air line, for aluminium tube from a hardware shop and for wooden dowel. All of these are sold by outside diameter, but they do not all measure the same. Copper is close to 12.0 mm, air line can be a tenth or two under, and dowel swells with humidity and is often 12.2 to 12.4 mm. Close a caliper on the piece you have, at the place where the clip will sit, and type that reading in place of the 12 used here.
Clearance, wall and material
This page adds 0.2 mm of clearance, which gives a bore of 12.2 mm. That suits hard, round tube. For soft air line, which squashes a little as it enters, keep 0.2 mm; for dowel or painted tube raise it to 0.3 or 0.4 mm. The wall is 2 mm and the opening 95 degrees, so the gap between the arms is about 9 mm and the tube has to be pressed through it. A small clip has short arms, and short arms are stiff: do not go above a 2.2 mm wall at this diameter in PLA or the arms crack before they open. PETG bends further and is the better material for a clip that will be opened and closed more than a few times.
Printing
Stand the clip on one of its two C-shaped faces, so that each layer is a complete ring around the tube. Lying on its foot, the arms would be built from short stacked arcs that split apart the first time the tube is pushed in. In the upright position the part covers about 28 by 14 mm of the bed and is 12 mm tall. It needs no supports and no brim. Three perimeters at a 0.2 mm layer height make the 2 mm wall solid. Print a row of them in one job: a single small clip gives each layer too little time to cool and the top comes out soft.
Fixing it
The tab reaches 12 mm beyond the clip and is 3 mm thick, with a 4.2 mm hole in its middle for a 4 mm screw. Use a pan head or a washer, since a countersunk head acts as a wedge and can split the tab. For light tube like this one tab is enough. Fix the clip first, then press the tube in from the front, supporting the arms with a thumb on each side if the fit is tight.
Outline drawing
Schematic, not to scale. The clip is 12 mm wide along the pipe and about 14 mm high.
Parameters the generator will use
| Setting | Link parameter | Value |
|---|---|---|
| Model | model | pipe_clip |
| Pipe diameter | diameter | 12 |
| Fit clearance | fit_clearance | 0.2 |
| Clip wall thickness | wall | 2 |
| Clip width along the pipe | width | 12 |
| Opening angle, degrees | opening | 95 |
| Screw tab length | tab_length | 12 |
| Screw tab thickness | tab_thickness | 3 |
| Screw hole diameter | screw_diameter | 4.2 |
| Number of screw tabs | tabs | 1 |
All lengths are in millimetres. Outer size from these values: about 28.2 x 12 x 13.97 mm.
Open the generator with these values
This model needs the $7 licence key: one payment, one key, and it opens all five paid models. Get a licence key on Gumroad ($7)
The pipe and cable clip needs a licence key: without one the generator shows the model locked, lists the values from this link and fills them in as soon as you unlock. The fitted drawer organiser bin is the free model and downloads with no key.