Contents
- Motivation and Purpose
- Using an Animation to Visualize Key Concepts
- Working With the Model
- Create the Model Animation
- Reference Links
Motivation and Purpose
I made a parametric bayonet connector for AC hoses, to attach such hoses to a mobile AC unit and a typical window kit taking the hot air outside. It is part of my Air Conditioning Collection on MakerWorld.
And of course, I prefer code over using some GUI CAD application, leading straight to OpenSCAD as the established standard for 3D-models-as-code. It is also one of the few ways MakerWorld models can be made customizable by the end user.
The connector allows attaching a hose with a simple push and a short twist, instead of needing a threaded joint or tools every time the hose is removed.
The design has three printable parts:
- A female connector with bayonet slots on the inside.
- A male connector with matching lugs.
- A female adapter with a wider fitting section for joining to an existing tube, like the one on an air intake cover.
The male lugs fit into the slots in the female connector. Push the parts together, twist them, and the lugs travel along the horizontal parts of the L-shaped slots. This is the same basic idea used by bayonet light fittings, camera mounts, and other quick-release connectors. See the Bayonet mount overview for useful background.
The hose itself is held on the printed connector with a worm-drive hose clamp. A screw on the clamp pulls the perforated band tight around the hose. See the Hose clamp reference for an explanation of that mechanism.
Using an Animation to Visualize Key Concepts
The OpenSCAD file contains code that creates a 10-scene animation. It shows the female connector turning to expose the slots, the hose and male connector moving into position, the male part twisting to lock, and the parts separating again. It also emphasises the parametric nature of the model by showing a change of the two main parameters, hose diameter and fitting height.
The animation is not just decoration — it makes the hidden bayonet slots easier to understand before printing the parts.
Working With the Model
1. Get the Files
Clone the things repo to get all required model files.
Install the OpenSCAD Nightly Build to view SCAD files, or alternatively add a SCAD live preview extension like Carve to VS Code.
The hose-connector-multi-plate.scad script targets some special features offered by MakerWorld, using the bespoke mw_plate_N() module names. To see this, open the MakerWorld Parametric Model Maker, where you can also download a 3MF file for your slicer.
For creating the animation video, the project also includes a subtitle file named subtitles.srt.
2. Choose the Dimensions
Open the MakerWorld Parametric Model Maker link. Wait for the model to load, then use the parameter controls to enter your measurements in millimetres:
- Set
hose_diameterto the inside diameter of your hose. - Set
hose_connector_heightto the length of the straight fitting section. - Adjust
wall_thicknessif you prefer a different wall size. - Adjust
tolerance_gapif your printer consistently makes holes too tight or too loose.
The default values are a 150 mm hose diameter, a 45 mm fitting height, a 2.5 mm wall thickness, and a 0.15 mm tolerance gap. The diameter and length are limited by what fits into your printer's build volume.
Measure your real hose before entering the diameter value; nominal hose sizes are not always the same as their measured inside diameter. Check the preview after changing the parameters and make sure the hose can slide over the fitting by using the measuring tool in your slicer. Section 4 explains how to download the customized 3MF with all three plates.
3. Inspect the Assembly
Open hose-connector-multi-plate.scad in OpenSCAD and press Preview (F5) or Render (F6). The script starts with the parts arranged as an assembly. The file uses lower detail for previews and finer curves for final output, so the preview should be faster than a final render.
The variables animate = 0 and local = 0, set at the top of the script, fit the model maker case. Comment the line with those settings and uncomment the line below it for local use and watching the animation within OpenSCAD
The MakerWorld model creator looks out for the three modules mw_plate_1(), mw_plate_2(), and mw_plate_3(), placing each printable part on its own plate.
4. Export the MakerWorld Plates
Upload the SCAD file through the MakerWorld Parametric Model Maker link above and set your dimensions in the customizer. The generated download is a 3MF containing three plates:
- Plate 1: the female hose connector.
- Plate 2: the male hose connector.
- Plate 3: the female adapter with the tube extension.
Open the 3MF in your slicer, check the fit and orientation, and slice the parts. The models are intended to print without supports on a printer that can handle 45° overhangs.
Do not use PLA for these parts. Use a material with better heat and UV resistance instead, such as PETG or PCTG, and choose a material and print settings suitable for the temperatures and environment around your AC equipment.
5. Attach the Hoses
Push each hose over its connector. Do not forget to fit a worm-drive hose clamp over the hose end before that, and tighten it carefully. The clamp is not included in the animation, but it is needed to secure the hose to the printed connector.
To connect the printed parts, line up the male lugs with the female slot openings, push the male connector fully home, and twist in the direction marked on the outside of the female connector housing. To remove it, twist in the opposite direction.
Create the Model Animation
The SCAD file divides the animation video into 10 scenes and uses OpenSCAD's $t animation value to progress through them, going from 0.0 to 1.0 in steps depending on the amount of requested frames. OpenSCAD documents $t, animation steps, and camera variables in its animation documentation. The OpenSCAD documentation page also links to the language reference and command-line manual.
From a terminal in the model folder, run the commands from the README. On Windows, OpenSCAD is likely not on your PATH and a working command may look like this:
"C:\Program Files\OpenSCAD (Nightly)\openscad.exe" -o frame.png --colorscheme "Nocturnal Gem" --animate 180 --camera=400,400,-300,0,0,50 hose-connector-multi-plate.scad
convert -delay 7 -loop 0 frame*.png hose-connector-animation.gif
ffmpeg -y -framerate 6 -i frame%05d.png -vf "subtitles=subtitles.srt" -c:v libx264 -pix_fmt yuv420p hose-connector-animation.mp4
The first command asks OpenSCAD for 180 animation frames and defines the camera position by specifying an eye line. The second combines the generated frames into a looping GIF using ImageMagick. The last command creates a MP4 video at six frames per second and burns in the captions using FFmpeg. On Windows, these last two commands are probably better executed in a WSL virtual machine.
On Linux or macOS, replace the Windows executable path with openscad if it is on your PATH. Recent ImageMagick installations may use magick instead of convert, so the second command may be:
magick -delay 7 -loop 0 frame*.png hose-connector-animation.gif
The frame files are temporary render output. Keep the GIF or MP4 and remove the individual PNG files when you are finished and do not need them anymore.
