Shannon McGarry
Find clear answers to the top 20 Autodesk Fusion technical questions, including modeling, assemblies, simulation, and CAM issues. Get quick fixes and links to deeper guides.
Elevate your design and manufacturing processes with Autodesk Fusion
1. Why won’t my sketch fully constrain in Fusion?
This happens when geometric or dimensional constraints are missing. Small gaps or misaligned endpoints often cause under‑constrained sketches. Use Show Constraints, apply Coincident constraints to fix loose endpoints, and avoid projecting unnecessary edges. Learn more here.
2. Why does Fusion say my profile isn’t closed when extruding?
Open profiles occur due to tiny gaps, overlapping lines, or misaligned endpoints. Turn on Sketch → Show Profile, zoom in carefully, and connect endpoints with Coincident, Extend, or Trim tools. Get an in-depth explanation here.
3. How do I convert an STL/OBJ mesh into a solid?
Use Mesh → Convert Mesh, but reduce the triangle count first to avoid warnings. Clean meshes process more reliably inside the solid modeling environment. See additional details here.
4. Should I use bodies or components in my design?
Use components for movable parts, assemblies, or manufactured parts. Use bodies for simple single‑part modeling or early conceptual design. Proper structure avoids downstream assembly issues. Learn more about components vs. bodies here.
5. Why are my joints acting unpredictably?
Joints fail when origins are misaligned or placed on unstable geometry (e.g., tiny edges). Recreate the Joint Origin, verify axes, and use As‑Built Joints when appropriate.
6. Why isn’t constrain components giving me the result I expect?
Because it removes one degree of freedom at a time, you often need two or three constraints to fully lock down movement. Use the Degrees of Freedom indicator to see what’s still open.
7. Why do external component links break when files are moved?
Fusion stores links relative to the cloud project. Moving or renaming files outside Fusion Team breaks references. Use Relink External References, and always move files inside Fusion’s Data Panel.
8. Why are drawing views slow or missing edges?
Large assemblies or detailed imports cause slow drawing regeneration. Use Raster View, suppress heavy components, or simplify geometry before drawing creation. See here for more information on drawing views.
9. How do I set up a simulation correctly?
Apply a material, define constraints, assign loads, and refine the mesh. Skipping any of these causes solver issues. Start with simple load cases before adding complexity. Learn how to set up Fusion simulations here.
10. Which simulation study type should I use?
Choose the appropriate simulation type based on behavior:
- Static Stress → basic loading
- Modal → vibration
- Thermal → heat flow
- Nonlinear → large deformation
- Event Simulation → impact/time‑dependent
Learn more about the simulation types in Fusion here.
11. How do I fix a simulation that won’t converge?
Refine the mesh, use contact simplifications, provide more realistic constraints, or switch to nonlinear analysis. Mesh refinement near stress concentrations often solves convergence problems. Learn more about how to fix simulation studies in Fusion here.
12. How do I prepare plastic parts for injection molding simulation?
Check for uniform wall thickness, remove abrupt transitions, apply proper draft, and specify gate placement. Early simulation helps predict short shots, warp, and sink marks. Learn more about injection molding simulation in Fusion here.
13. Why are my CAM toolpaths slow to regenerate?
Complex models create excessive toolpath calculations. Suppress unnecessary features, simplify the model, use silhouette selections, or temporarily disable timeline history for speed. Learn how to optimize your Fusion toolpaths here.
14. Which toolpath should I use for 3‑axis vs. 5‑axis machining?
- 3‑axis: adaptive, parallel, contour
- 3+2: oriented machining using fixed rotations
- 5‑axis: advanced multi‑axis strategies
Choosing the correct strategy improves surface finish and machining efficiency. Learn how to choose the correct machining strategy here.
15. Why is my post processor generating incorrect G‑code?
Incorrect G‑code usually comes from mismatched machine settings, tool numbers, or offsets. Verify your machine’s configured post and adjust parameters in the Post Process dialog. View the Fusion post-processor library here.
16. How do I safely verify toolpaths?
Use Simulate → Stock + Toolpath + Collision Checks before posting code. Turn on tool transparency, check for gouges, and step through operations slowly. See an in-depth description on how to verify toolpaths in Fusion here.
17. Why is Fusion running slowly on my computer?
Slow performance often results from long timelines, heavy graphics, or overly detailed assemblies. Reduce visual fidelity, suppress parts, or convert imported geometry to simpler B‑reps. Learn how to improve Autodesk Fusion performance here.
18. Why can’t I edit or move certain geometry in an imported model?
Imported STEP, IGES, or SAT files usually come in as parametric history-free bodies, which limits editing options. To modify them, convert the model to Direct Modeling mode or use tools like Move, Press Pull, Delete Face, and Replace Face. For deeper editing, activate the timeline and use Feature Recognition to rebuild parametric features when appropriate.
19. How do I sync ECAD and MCAD changes?
Update the PCB in the electronics workspace, push changes to Fusion, then update the enclosure. This ensures mechanical and electrical constraints stay aligned. Learn more about how to sync ECAD and MCAD changes in Fusion here.
20. How do I fix broken toolpaths after making design changes?
Toolpaths become invalid when geometry references (faces, edges, or bodies) change after edits. To fix this, open each affected operation and reselect geometry, then regenerate. For more stable CAM workflows, select larger, more stable surfaces instead of small edges, and use Fusion for Manufacturing or the Fusion Manufacturing Extension to rebuild complex paths more reliably.