Use case
Design 3D printed replacement parts from a description
The part that broke is rarely on Thingiverse in the exact size you need. With SpeakCAD you measure the original with calipers, type the numbers, and get a replacement that fits the first or second time.
Prompts that work
Copy one, change the numbers to yours, and the model appears in seconds.“A replacement knob 30 mm diameter, 18 mm tall, 6 mm D-shaft with a 0.5 mm flat, 12 mm deep, with a pointer line on top.”
“A fridge shelf clip: 25 mm wide hook that grips a 3 mm glass shelf, with a 10 mm tab that slots into a 4 x 12 mm hole.”
“A washing machine foot, M10 threaded stud 30 mm long, 50 mm diameter base, 15 mm tall, rubber pad recess 2 mm deep.”
Why replacement parts are the best 3D printing use case
Appliances, furniture and tools fail at their cheapest plastic component: a knob, a clip, a foot, a hinge pin. Manufacturers charge a fortune for spares or do not sell them at all. A 3D printer plus a few grams of PETG solves the problem for cents, but only if you can model the part.
That modelling step is where most people give up. Learning Fusion 360 to draw a knob is a weekend, not an evening. SpeakCAD removes the step: you describe the geometry and the numbers you measured, and the AI writes a parametric model that respects them exactly.
How to measure for a replacement
- Mating dimensions first. The shaft, the hole, the slot the part has to fit. Measure these with calipers and give them to the millimetre (or tenth).
- Overall envelope second. Width, height, depth. Approximate is fine; you can tweak later.
- Fit type. Tell SpeakCAD whether the part must press on (tight), slide (loose) or snap. It applies the right clearance automatically: about 0.2 mm for press fits, 0.4 to 0.6 mm for sliding fits.
- Material and orientation. Mention if the part takes load so the AI adds thickness or fillets where it matters.
Iterate for free after the test print
Print the first version, test the fit, and come back to the chat: "the shaft hole is 0.3 mm too tight" or "make the lip 1 mm longer". Small corrections re-download for free, so a replacement part typically costs one credit even with two or three fit iterations.
Common replacement parts people generate
- Appliance knobs and dials (oven, washer, mixer, amplifier)
- Clips and hooks (fridge shelves, curtain rails, cable guides, blinds)
- Feet and glides (furniture, laptops, kitchen appliances)
- Hinge pins and bushings
- Battery covers and remote-control lids
- Vacuum cleaner adapters and attachments
- Drawer runners and stops
Examples from the gallery
Questions
Yes. Attach a photo and give the key measurements in the message; the AI uses the photo for the shape and your numbers for the dimensions.
For a shaft or peg that must not spin, ask for a press fit (about 0.2 mm clearance). For sliding parts, 0.4 to 0.6 mm. If you do not specify, SpeakCAD picks the fit that matches your description.
Yes for coarse printed threads (M8 and above) and for thread-insert or heat-set pockets. For small threads it is usually better to print a hole and tap it, which you can ask for.
Related use cases
Brackets & mountsDescribe what you need to hold, where it mounts and which screws you have. SpeakCAD generates a strong, printable bracket as STL or 3MF in minutes.EnclosuresDescribe your PCB size, ports and mounting, get a snap-fit or screwed enclosure as a print-ready STL. Raspberry Pi, Arduino, ESP32, sensor boxes.Gears & mechanismsSpur gears, racks, pulleys, ratchets and knobs from a text description: module, tooth count, bore, keyways. Print-ready STL and 3MF, watertight.