CAD troubleshooting
Find the first broken relationship in sketches, features, imports, mates, drawings, and exports.
Start with the first operation that no longer behaves correctly. Later errors often come from that earlier failure. Keep the model's intended and relationships in view while repairing it.
Before making a large repair, save a named version so you can get back to the model as it is now. Change one thing at a time and check what happens.
A sketch still moves
An under-constrained has at least one remaining . A circle can have a fixed diameter while its center remains free to move. A dimensioned rectangle can still slide if it is not located relative to the .
Gently drag the line, circle, or point that moves. Watch whether its size, position, or angle changes, then add the constraint it needs: Coincident to a reference, Horizontal, Vertical, Concentric, or a position dimension.
Avoid using Fix to lock everything wherever you happened to draw it. In the practice plate, center the rectangle on the origin, put the holes on its centerline, and dimension their spacing. Then you can widen the plate without moving the holes out of place.
Some construction lines can still do their job even if their endpoints move. For example, a line can define the horizontal centerline without needing a fixed length. A hole center that must stay in one place does need its position constrained.
A sketch turns red
Look at the most recent constraint or dimension. It may duplicate a relationship already defined by a mirror, pattern, equality, or another dimension.
Undo the last change and inspect the existing constraints. If a hole is mirrored about a centerline, an independent dimension on the mirrored center may be redundant. Keep the relationship you want the sketch to follow, and remove the extra dimension or constraint that conflicts with it.
A reference dimension reports a value determined elsewhere. It does not drive the sketch. Use it when you want a measurement without another control on the geometry.
A region will not extrude
Check for gaps, overlapping segments, duplicate circles, and construction lines where the boundary should be real. Zoom into joints between lines and arcs. Apply Coincident where endpoints must meet.
Inspect the selected region. Nested loops can create several selectable areas, such as the plate around its holes and the circular hole regions. Selecting all of them can fill an opening you intended to leave clear.
Check the operation and direction too. New makes another part; Add needs material that joins an intended part; Remove must intersect the part you want to cut. Review the merge or affected-part scope when several solids are present.
A later feature fails
Find the earliest failed feature in the list. Roll back before it and inspect the preceding geometry. An edge referenced by a later sketch may have been removed by a changed pocket or .
Repair the reference using a stable face, , axis, or layout entity where possible. Do not keep selecting a new nearby edge without checking whether it represents the same design relationship.
If rounding an edge keeps breaking a later sketch, move that finishing fillet later in the feature list. Keep a radius earlier when the part’s shape depends on it, such as the curve of a guide.
A linked part does not update
Check what the link references: the current workspace, a named version, or another document's selected state. may still use an older version even after someone updates the source model.
Inspect the reference or update indicator, review the change, and adopt the intended version. Then check the part’s shape, mounting holes, and fit with the surrounding parts. If a sketch updates but a mounting hole stays behind, inspect whether the hole is actually constrained to that sketch.
For custom features, the toolbar's selected version and an existing feature's linked version can differ. Use Custom features to check both.
An assembly is stuck or loose
Inspect fixed instances, groups, and . If a part should move, check that it is not fixed. Two mates that constrain the same relationship can remove movement or conflict.
Check the mate type. Revolute allows rotation, Slider allows , and Cylindrical allows both along its axis. Check the connector's primary-axis direction, offset, and limits. A valid mate with the wrong connector orientation can put a part on the wrong side of a plate.
Temporarily one mate you suspect is causing the problem and try moving the part. Use the result to decide whether to restore or repair that mate. Removing every mate at once makes it harder to identify the cause. For a linkage, remember that its closed loop already connects the parts through several joints.
An imported model is wrong
Measure a known dimension. A factor of 25.4 suggests an inch/millimeter mismatch. Confirm the original file, units, and import settings before applying a scale transformation.
If the file is a mesh, exact circular or planar references may not be available as expected. Look for a solid or native model from the supplier. If you only need to reserve space, a simple model with measured dimensions may be enough.
Check the part number and configuration. A perfectly imported model of the wrong rail length or option still produces a wrong design.
The export or drawing disagrees
Confirm the selected configuration, model state, and drawing reference. Update the drawing when its referenced model changes, then inspect the affected dimensions and views.
For a cutting profile, check that you exported the intended planar face or sketch, with the correct units and boundaries. For a print, measure the opened mesh in the . Do not repair a unit mistake by changing the 's actual dimensions.
Keep obsolete files separate from the approved manufacturing package. A corrected model is not enough if a builder still has the earlier .
The model is slow
Hide detail that does not help the current task, such as unnecessary thread geometry or complex repeated hardware. Use simple models with accurate mounting holes and overall dimensions when you do not need all the detail. Organize subsystems and references so a local change does not regenerate unrelated geometry.
Avoid creating large patterns merely to make the display look detailed. Keep complete manufacturing geometry where needed, while giving the whole-robot assembly a manageable representation.
After a repair, repeat the edit or movement that originally failed. Check the intended dimensions, dependent parts, and export rather than accepting the disappearance of the red feature alone.