FeatureScripts: Automating FRC CAD

What FeatureScript is#

FeatureScript is Onshape's built-in programming language for creating custom features. Onshape's own built-in features (Extrude, Fillet, Helix) are themselves written in FeatureScript. The community uses it to package repetitive modeling tasks into reusable features that show up in your toolbar just like native ones. You don't have to write FeatureScript to benefit — you just add other people's scripts. The official docs live at cad.onshape.com/FsDoc.

The FRC FeatureScripts worth knowing#

The FRCDesign.org FeatureScript list curates the most useful ones. Highlights:

• Tube Converter (Julia's FeatureScripts) — converts a plain extrusion into a real punched FRC tube, with presets for standard hole patterns. This is the everyday tool for making drivetrain and superstructure tubes.
• Extrude Individual (Julia's FeatureScripts) — extrudes multiple sketch regions as separate parts in one feature, perfect for making several tubes (a whole drivetrain) at once.
• Belt & Chain Gen — generates parametric belts and chains routed around your pulleys/sprockets, with correct lengths.
• Robot Shaft (Alex's FeatureScripts) — generates shafts with options for hex, rounded hex (13.75 mm OD), MAXSpline, and end-retention features.
• Robot Spacer (Alex's FeatureScripts) — generates round, hex, or MAXSpline spacers.
• Part Lighten (2471 FeatureScripts) — adds lightening pockets/ribs with weight-savings estimates, so you can cut mass intelligently.
• Origin Cube — places a clean origin reference for assembly mating and can carry design constants.

Why FeatureScripts matter#

Modeling an FRC tube by hand (cross-section, hole pattern, linear pattern, repeat for every tube) is slow and tedious. Tube Converter turns that into a few clicks with a guaranteed-standard hole pattern. Belt & Chain Gen removes the painful geometry of routing chain. These scripts let small teams produce professional, manufacturable designs quickly and consistently — which is the whole point during a six-week season.

How to add and use them#

1. Open the public FeatureScript Document (linked from the FRCDesign.org FeatureScript list).
2. Right-click the custom-feature tab and choose to add it to your toolbar.
3. The feature now appears in your Part Studio toolbar for all your Documents.

Good practice#

• Standardize a small set of FeatureScripts across your team so everyone's models look and behave the same.
• Pin a known version where possible; if a script updates and changes behavior mid-season, it can disrupt existing models.
• Understand what the script does before relying on it for a manufactured part — for example, confirm Tube Converter's hole pattern matches the tube stock you are buying.

FeatureScripts plus a good parts library are the two superpowers that make Onshape so effective for FRC. The current community-standard parts library is FRCDesignLib (accessed via the FRCDesignApp Onshape plugin), which has superseded the older MKCad library.