Start from the 20 × 20 × 17 cast corner bracket that Adafruit, OpenBuilds and Misumi sell, then make it fit your frame: pick your rail's slot standard and screw, lengthen the legs, thicken the plate. The model rebuilds in your browser as real CAD, so the STEP drops straight into Fusion or FreeCAD.
The real generator runs in your browser: set the parameters, then download STEP or STL. Nothing to install, no sign-up.
The first open downloads the CAD engine (about 20 MB).
Each parameter below rebuilds real geometry on every change — this is parametric CAD, not a scaled mesh.
| Parameter | Default | Range | What it does |
|---|---|---|---|
| Rail slotSLOT | 6 mm | 6 / 5 / 4 mm | 6 mm: EU / B-type / V-slot. 5 mm: I-type. 4 mm: China GB. |
| ScrewSCREW | M5 | M3 / M4 / M5 | Clearance holes per ISO 273 medium: 3.4 / 4.5 / 5.5 mm. |
| Leg lengthLEG | 20 mm | 20 – 60 | 20 matches the cast 20×20×17 bracket; longer legs add a hole every 20 mm. |
| WidthWIDTH | 17 mm | 15 – 20 | 17 is the cast-bracket width; 20 fills the whole profile face. |
| Plate thicknessTHICKNESS | 4 mm | 2 – 6 | Cast brackets are 3 mm; printed ones are usually 4 mm or more. |
| Slotted holesSLOTTED | on | on / off | 3 mm of travel along the leg to square up the frame. |
| Locating tabsTABS | on | on / off | Two 4 mm tabs per leg drop into the slot and stop the bracket turning. |
| Side wallsSIDE_WALLS | on | on / off | Triangular walls on both sides, like the cast bracket. |
Every parameter can go in the page's link, so one link opens exactly the part you want. Example (6 mm slot (EU / B-type / V-slot), M5 screws, 30 mm legs):https://www.forgent3d.com/en/generators/2020-corner-bracket-generator?SLOT=6&SCREW=M5&LEG=30
STEP AP214 in millimetres, exact B-rep — it opens directly in SolidWorks, Fusion, FreeCAD, Onshape or Inventor, and goes straight into a CNC quote form. STL for the slicer is one click too.
| This generator | Typical online STL generator | Vendor CAD library | |
|---|---|---|---|
| Any size within the range | Yes | Yes | Catalog sizes only |
| STEP with exact surfaces | Yes | Usually an STL mesh only | Yes |
| Changes the sliders don't cover | “AI edit” on the page | No | No |
| Account needed to download | No | Usually no | Often |
Every parameter is a link parameter; the link below opens the example part. ChatGPT, Claude or any assistant can write one like it from the parameter list (names, units, ranges) at: parameter list (JSON)
Example: https://www.forgent3d.com/en/generators/2020-corner-bracket-generator?SLOT=6&SCREW=M5&LEG=30
Press “AI edit” in the generator and say what to change — a keyway, holes, a different shape. The AI edits the part's model.py and it rebuilds in your browser, with undo. A few edits a day are free without signing in; to keep the result or go further, copy it into your models and continue with the AI agent.
Edit with AI →For bigger changes, several rounds, or a part you want to keep: copy it into your models (free account). The Forgent3D AI agent reads the model.py, edits it, rebuilds it and checks the result itself.
Copy and continue with the AI agent →M5 is the standard for 6 mm-slot 2020 (the Misumi, OpenBuilds and Alux brackets all take M5×8 with a slide-in or drop-in T-nut; Misumi also makes M4 versions). With the default 4 mm printed plate, use M5×10 — a cast bracket's 3 mm plate takes M5×8, and printed brackets on MakerWorld list M5×10, or ×12 with a washer.
The tabs are 4 mm wide, the same as the OpenBuilds and Adafruit cast brackets, so they slide into 6 mm and 5 mm slots with room to spare; a 4 mm GB slot gets a 3.2 mm tab. Tight tabs are the most common complaint about printed brackets — if your rail is unusual, switch the tabs off.
PETG, ASA or ABS — makers report PLA brackets slowly deforming under load. More perimeters beat more infill: 4–5 walls is the common advice. Print it lying on one side wall; nothing needs supports.
https://www.forgent3d.com/en/generators/2020-corner-bracket-generator?SLOT=6&SCREW=M5&LEG=30 opens exactly that bracket. Download STL to print it (PETG is the usual choice), or STEP for your frame assembly.
Not with the sliders — the bracket follows the cast 20 × 20 × 17 part. Press “AI edit” in the generator and describe the change, or copy the bracket into your models and work it through with the AI agent.
Yes. Models you generate and the STL / STEP files you export are yours: print them, sell the prints, or use them in a product. No attribution to Forgent3D is required.
Already have your own .scad file? Convert OpenSCAD to STEP → · Preview it in the browser →
