About parametric needle selector

overview

This project began with modeling a single replacement needle selector for a friend's knitting machine and resulted in a parametric CAD model able to generate selectors that can be customized to fit practically any flatbed knitting machine's specifications. This allows fiber artists to replace broken selectors with 3d prints for only a few cents worth of material or create a full set of customized selectors with materials and lettering that make them infinitely more interesting than the standard beige plastic selectors. I like to smile when I reach for my favorite pair of scissors or ink pen, hopefully with this model operators of knitting machines can smile too when they reach for their personal selectors.

The parametric model was created using FreeCAD which allows anyone to download and use the file for free to generate models that match their specific needs. The genereated model is built up using a series of 5 drawings that calculate their dimensions based on parameters in the file's "Parameters" spreadsheet. Simply changing values like "Needle Gauge" or "Board Width" immediately regenerates the model as specified. Once a desirable model has been generated it can be exported as an `STL` file for further customization in another 3D program such as Blender or immediately sliced in a program like Orca Slicer for 3D printing.

I really enjoyed working on this project as it combined a range of interests and skills I've collected over the years. It also gave me a chance to dive into an unknown subject and lean on GenAI tools such as Google Gemini to accelerate the time to result in an objective-based learning approach to modeling and 3D printing. I had no idea that learning 2D CAD basics back in 2016, 3D modeling using Blender on a whim in 2023, 3D printing in 2024, and parametric thinking as a software engineer over the past few years would eventually combine to help a friend and release a free utility for a niche community. Now I just have to learn how a knitting machine actually works!

Downloadable 3D Models: Printables - TinkerSky - Knitting Machine Needle Selectors (4.5mm gauge)
Downloadable FreeCAD File: GitHub - TinkerSky - parametric_needle_selector
Video Demo: YouTube - TinkerSky - Parametric Needle Selector Guide

Software: FreeCAD, Blender, Orca Slicer, Google Gemini
Printer: Creality Ender 3 V3 KE

challenges and successes

Researching, reviewing, and learning new open-source CAD and slicer software to create and prepare the model for 3D printing

Learning basics of 3D printing, industrial design, and material science in order to troubleshoot and calibrate prints

Thinking programmatically when designing the model in order for it to be easily updated and regenerated in a parametric fashion

Researching an unknown problem domain (machine knitting) and speaking with a subject matter expert (my friend haha) in order to inform iterative design of the model

Rapid prototyping to dial in the design and production of the part aiming first for a functional design (MVP) then a retail level of production quality (stretch goals) in the end result