Show HN: Nasscad - local-first 3D CAD for browser and Windows

Display and Workspace

🖥 1920×1080 or higher is recommended for a spacious workspace.

On smaller screens, move, resize or hide panels with ☰ Panels or H.

The compact Performances ▾ menu groups the advanced settings; the space available for modelling depends on the panels you keep open.

Getting Started

🚀 Start in the menubar (left of ☰ Panels) opens the welcome card: Interactive tutorial, Import a model, Open project or NassScript demo.

Click 🚀 Start again, the × or Esc to close it.

Choose a demo NassScript demo offers Solar system and Four-cylinder engine. Only the chosen script is downloaded when launched. Your unfinished text in the Script editor is preserved.

Stop and Edit

Open ⚡ Script and press Stop to stop a running script.

In the engine demo, Stop freezes the visible parts so you can select and edit them. The demo's close/restore control cleans up its scene.

Save Your Work

Use Save project as for a NASSCAD JSON project; Load project reopens it.

Export ▾ writes a model for other tools.

STEP Import and Export - Current Workflow

Import and Browse Assemblies

Use Import to open a STEP AP203, AP214 or AP242 file.

When the reader exposes the source assembly structure, the Objects panel groups parts into assembly folders. Expand folders to browse the model; click a folder to select its parts.

Part names, placements and available colours are retained.

MEDUSA adds per-face colours and native processing for large assemblies; it is included in Windows Setup and Portable.

Surface Quality and Large Files

The current import pipeline improves tessellation topology and keeps available OCCT surface normals on eligible bodies. This gives smoother curved faces while preserving sharp boundaries. Bodies that need repair or lack usable source normals use a fallback.

Native STEP streaming and the Turbo path support large assemblies; runtime and memory use still depend on the file, its complexity and the machine. A faster cached import does not measure the first-import cost.

PMI and Assembly History

Supported AP242 files can expose graphical annotations and semantic PMI / GD&T in the PMI panel. The information must be present in the source and supported by the reader.

The assembly tree describes parts and instances; it does not recover the original sketches, constraints, extrusions or modelling feature history.

Imported PMI display is not a promise that all annotations will survive export.

Export STEP in Three Protocols

Use Export > STEP, check the export scope (the selected objects or the whole design), then choose AP203, AP214 or AP242.

Export can write separate named bodies as components, with supported body and face colours. The exported component structure need not reproduce every level of the original assembly hierarchy.

MEDUSA performs native export in the Windows edition; the browser has a JavaScript fallback when the native export service is unavailable.

Reuse an Intact Source B-Rep

For eligible STEP bodies imported through MEDUSA and kept geometrically unchanged, native export can reuse the referenced source B-Rep with its supported placement transform, instead of rebuilding the body from display triangles.

If MEDUSA restarted and the source file remains available in the session, NASSCAD can reload the source B-Rep before export. Read the log to confirm which bodies used this path. If a reference or source cannot be recovered, export falls back to the mesh representation.

Export After Editing a Mesh

CSG results, edited meshes and bodies without a usable source B-Rep export from their current geometry. Supported analytic primitives can use analytic representations; connected coplanar triangles can become planar B-Rep faces when compact.

Other geometry can use AP242 tessellation or AP203/AP214 faceted B-Rep.

The Exact / Robust / Faceted option controls the writer strategy and declared accuracy: Exact does not reconstruct lost analytic surfaces or the original CAD history.

Keep the original STEP, and reopen important exports in the receiving CAD tool to check body count, dimensions, placement and appearance.

Updates and Fixes - 26 October 2026

Preview Fillets and Chamfers

Select one solid, then open Quick Fillet. Choose Round or Chamfer and set the finish size.

Use Preview all for every sharp edge, or Pick edges followed by Preview selection for selected edges and groups.

Inspect the separate 3D window, then choose Apply to commit or Back to adjust. Preview does not replace the source object. If a requested finish cannot be built, read the status and any adjusted value before applying.

Finished Objects and Surface Display

A committed fillet or chamfer remains selectable for further work and Undo. Quick Fillet now keeps flat faces visually flat and preserves the smooth surface normals of curved faces.

STEP import and native MEDUSA booleans also preserve available surface normals; repaired or unsupported geometry uses a fallback. These are display improvements, not a guarantee that an imported model has been healed.

Coplanar Through-Cuts

Boolean operands are now evaluated in one shared local frame. This prevents tiny transform-rounding residues from leaving a membrane when a cutting tool ends on the same plane as the solid.

The change is shared by Union, Subtract, Intersect and CSG-tree evaluation; it is not tied to one model. A Union action that includes objects marked Hole still subtracts those objects.

Recalculate an Older Result

Updating NASSCAD does not rewrite geometry already saved in a project. Keep a copy of the project, select the old CSG result and use Re-run to recalculate its operation, or Deep to evaluate its construction tree.

If the source operands are no longer available, return to an earlier project or re-import the source. Previously baked fillets need their source solid and edge selection again.

Check the Actual Solid

For a through-hole, inspect both sides and use another view or export to confirm that it is open. A manifold result alone does not prove the intended shape: an unintended thin membrane can still be manifold.

Intentional blind holes and thin floors are retained; this correction does not automatically extend cutters or erase thin details.

Gear Dialog and Desktop Update

Gear.Gen / Pulley.Gen opens within the workspace and keeps its expanded mating-gear controls accessible. Use the dialog scroll area on a smaller screen.

Windows users should install the refreshed Setup or replace the Portable executable; updating the website alone does not update an installed application. Setup and Portable include MEDUSA and its dependencies.

Latest Tools · 21 October 2026

🚀 Start

Open the welcome card from the menubar, to the left of ☰ Panels. It no longer appears automatically on an empty scene. Choose the tutorial, import, open a project or a NassScript demo. Click Start again, × or Escape to close the card. Opening the card does not clear your scene.

Clear STEP Import Cache

In Tools → Files · Utils, use Clear STEP import cache and confirm. This clears both cached parsing results (NSTP) and final geometry (NSPG) from IndexedDB.

Your current scene, saved projects and original files are kept. The next import is processed again and may take longer. This does not clear native MEDUSA B-Rep data held in memory.

MEDUSA Progress

In the Windows desktop edition, open the MEDUSA status/log panel. Progress bars adapt to the panel width; percentages remain visible and long details are shortened. Hover a progress row to read its full text.

Drag, resize or maximize the panel and use A− / A+ for its text size. The standalone engine uses its own console.

💬 Feedback

Use Send feedback to report a bug or suggest an improvement without an account or email. An internet connection is required. No project or diagnostic log is attached automatically; avoid confidential information.

📖 Illustrated User Manual

Read the complete English guide: Open HTML manual · Open PDF manual. Both documents are included in the desktop package for offline reading.

🧭 Interactive Tutorial

Learn the main tools in the real interface: highlighted controls, hands-on exercises and the four-state double-click cycle. Choose French or English. Practice starts from an empty scene; a control tour is also available with your current model.

What's New

Windows All-in-One

The Electron desktop app bundles NASSCAD, MEDUSA and their runtime dependencies. Choose Setup to install or Portable to run without installation. MEDUSA starts with NASSCAD and stops when NASSCAD closes.

Performances Menu

Performances ▾ groups STL, CSG, Pool, Watchdog and Workers. The controls, values and Auto modes are unchanged; the π control remains beside CSG resolution.

Copies and Materials

Duplicate and Copy/Paste retain Hollow box size and wall thickness. NASSCAD projects and Undo/Redo retain material identity, specular colour and shininess; Copy/Paste also retains face colour palettes.

Browser Booleans

Union, Subtract and Intersect use Manifold WASM when no MEDUSA engine is connected. With MEDUSA, they use native C++ with CPU parallelism. The CSG panel shows Manifold C++ · MEDUSA or Manifold WASM.

Export the Selection

📤 Export ▾ › Include: All design or Selected shapes - every format, STEP, IFC, section and JSON project included. With a single shape, the file takes its name.

Hide the Panels

☰ Panels in the menubar, or the ✕ of each panel: Tools, Objects, Properties / CSG and NassScript, one by one. H hides them all and brings back exactly what was shown.

NassScript Demos

Launch the real-date Solar system or our original four-cylinder engine from 🚀 Start in the menubar. Complete scripts and explanations are also in the NassScript docs - nasscad.com/nasscript_doc.html

🖥 Windows x64 - Electron All-in-One Setup

Run NASSCAD-4.7.0-Setup-x64.exe. All users is selected by default; Windows may request administrator permission. The installer lets you choose the installation folder and creates application shortcuts.

Portable

Run NASSCAD-4.7.0-Portable-x64.exe without installing the app. Runtime dependencies and MEDUSA are bundled. No BAT launcher or separate DLL installation is needed.

MEDUSA Lifecycle

Opening NASSCAD starts its own MEDUSA process automatically. Closing NASSCAD also stops that process. The desktop app communicates with MEDUSA through an internal process pipe, without a local HTTP server.

Status and Logs

Click the MEDUSA status button to view its logs. The CSG panel shows which boolean engine was used. Native MEDUSA computations use the CPU; the graphics card renders the 3D view.

🌐 Browser Edition - Optional MEDUSA Companion

Without MEDUSA Union, Subtract and Intersect work through Manifold WASM inside the browser. No companion installation is required for these operations.

Optional Windows engine Medusa_Engine_3.1.zip contains Nasscad_Medusa_Engine_3.1.exe with bundled DLLs. Run it separately while using the browser edition if you want native engine support. The automatic start/close and internal pipe described above belong to the Electron app.

🖱 3D View Navigation

• Left click Select an object - stays instant even on very large scenes
• Left click + drag Move selected object on the XZ plane. On multi-selection: drags the entire group - relative positions preserved, single Undo step.
• Shift + click Multi-select (N objects) - for CSG, alignment
• Left drag on empty zone Box-select - draw a selection rectangle. Shift = add to selection.
• Alt + left drag Pan full 3D - drag horizontal → left/right (XZ camera-relative), drag vertical → up/down (Y)
• Alt + right drag Pan the grid + all objects - useful for large scenes
• Right click + drag Orbit camera around the scene
• Middle click + drag Pan camera
• Scroll wheel Zoom in / out - speed set by the camera buttons /5 /2 1× ×2 ×5 ×10 (see Toolbox below)
• Single click on object Select the object (drag to move it)
• Double-click on object Each double-click moves one step:
  1. resize handles (drag corners or top handle) →
  2. dimensions (X/Y/Z values) →
  3. rotation rings (3 Cura-style rings) → back to nothing. Click on empty space to leave.
• Double-click on .gen object Reopens the generator dialog pre-filled with current parameters - live edit in-place (Cubic/Cylind/Tore/Pipe/Gear/Screw/Nut/Sketch/CircularText)

⌨ Keyboard Shortcuts

• Ctrl + Z Undo - up to 200 levels
• Ctrl + Y Redo
• Ctrl + D Duplicate selection
• Del / Backspace Delete selection
• Arrows ↑↓←→ Move object 1 mm (XZ plane, camera-relative)
• Alt + ↑ / ↓ Move object up / down (Y axis)
• Select all Select all objects using the EDIT toolbar button
• Ctrl + C / Ctrl + V Copy / Paste - offset along X; geometry, transforms, generator parameters, materials and face colour palettes retained
• L Show / hide 3D alignment handles
• S Magnetic snap - each press steps 1 → 0.5 → 0.1 → 0.01 → 0.001 mm → OFF. The toolbox buttons jump straight to a step.
• N Toggle light / dark theme
• 1 · 2 · 3 · 4 · 5 Camera views: 1 reset · 2 top · 3 front · 4 right · 5 reset
• Esc Deselect all / Cancel box-select / Close dialogs
• H Hide / show the panels - choose which ones in ☰ Panels, or with the ✕ of each panel

🔷 3D Primitives - 19 Watertight

Primitives are designed as closed solids for modelling and slicing. Check the exported geometry in your target slicer or CAD tool, especially after complex edits or operations on imported models.

Standard primitives (toolbox):

• Cube Box 20×20×20 mm - 6 flat faces
• Sphere Configurable resolution 8-256 segs (slider in Properties) · export at 2× resolution, capped 512 · smooth shading built-in
• Half-sphere Flat-capped hemisphere - same slider as sphere
• Cylinder 64 segs display / 128 segs export
• Cone 64 segs / 128 export
• Triangular pyramid Tetrahedron - isosceles triangular base + 3 triangular sides. Dim X/Z set base width/depth, Dim Y sets height. Apex above the base centroid; not a regular tetrahedron by default.
• Hollow pipe - straight segments + tangent bends (radius R_bend, real tube-bending). No section twist along the path. Outer wall + inner wall + sealed caps.
• Gear.Gen ISO involute gears (20° pressure angle) - module 0.5-8 mm, straight /