Precision editing
Snapped drags, exact values, 3D snapping, in-place timeline edits, typed transforms, and smart measurement.
The drag engine and modifiers
Every depth drag in HelioCad — push/pull on a face, extrude depth, fillet radius, hole depth, and move — runs through one shared drag engine, so the same habits work everywhere. A plain drag snaps to the unit step, holding Shift switches to fine steps, and holding Ctrl (Cmd on macOS) gives a free, unsnapped drag.
As you drag, a graduated ruler appears along the drag axis so you can read the distance against the model, and a value chip follows the cursor with the current number. The chip is editable: click it and type an exact value to land on it precisely.
- Plain drag — snaps to the unit step.
- Shift — fine steps for small adjustments.
- Ctrl / Cmd — free drag with no snapping.
- Value chip — type an exact number to override the drag.
Tip: Rough it in with a plain drag, then type the final number into the value chip. You get the tactile feedback of a drag and the exactness of a dimension in one gesture.
3D snapping and the HUD
Press K to toggle 3D snapping. With it on, drags and placements snap to vertices, edge midpoints, and face centers on the model, so a hole lands on the center of a face and a moved body seats against an existing edge. The Snap chip on the viewport toolbar shows the current state and toggles it with a click.
The bottom-left HUD keeps you oriented: a scale bar that adjusts as you zoom, and the cursor's XYZ position in model coordinates. When you select geometry or commit an edit, a brief flash on the affected faces confirms exactly what changed.
- K — toggle 3D snapping; the Snap chip shows the state.
- Snap targets — vertices, edge midpoints, face centers.
- HUD — scale bar and live cursor XYZ, bottom-left of the viewport.
- Flashes — selection and commit highlights confirm the affected geometry.
Editing the timeline in place
The feature timeline runs along the bottom of the Model workspace, mirrored by the Features node in the Browser. Hover any step and its footprint lights up on the model, so you can find which fillet or hole a step belongs to without reading its name. Drag the ⋮⋮ handle to roll the model back to that point in its history — later steps are suppressed, not deleted, and dragging forward replays them.
Double-click a fillet, chamfer, extrude, shell, offset, hole, or draft step to re-arm its gizmo on the model and edit it in place with the same drag and value-chip controls you used to create it. Apply replaces that step and replays everything after it. Before you commit, you can preview the exact rebuild and compare the original against the candidate, so a radius change deep in the timeline is never a leap of faith.
- Hover a step — its footprint highlights on the model.
- Drag ⋮⋮ — roll back to any point in history.
- Double-click — re-arm the gizmo for fillet, chamfer, extrude, shell, offset, hole, and draft steps.
- Apply — replaces the step and replays the rest; preview and compare first.
Tip: If a later feature fails after an in-place edit, roll back to the edited step and adjust the edit rather than deleting the failing feature — the failure is usually a reference the edit moved.
Adjust Model and typed transforms
The right panel has two tabs: Chat and Adjust model. Adjust model shows a card for the currently selected feature plus a slider and an exact-value field for every parameter in the model. Nudge with the slider or type the number, and the model rebuilds. Edits are transactional — each one lands as a replayable change in the history, so you can undo it or roll past it like any other step.
Move and Scale accept typed values as well as drags, so you can translate a body exactly 12.5 mm along Y or scale a part by a precise factor. Linear and circular patterns stay editable after the fact: change the count, spacing, or angle and every instance updates.
- Adjust model tab — a card for the selected feature plus sliders and exact values for every model parameter.
- Typed Move and Scale — exact translations and scale factors.
- Patterns — count, spacing, and angle are editable after creation.
Smart measure
With the Measure tool active, hover any face or edge for an instant readout: the entity type, area, perimeter, radius, and the ΔX / ΔY / ΔZ extents. Pin keeps a pair's readout on screen while you keep working. Distances are computed on the exact B-Rep geometry, not on the display mesh, so a measured radius is the modeled radius.
Auto Measure lays out a set of engineering dimensions over the model and tours them one at a time, so you can check a part the way a reviewer would. For mass, volume, surface area, and center of mass, open Inspect ▸ Mass properties.
- Hover readout — type, area, perimeter, radius, ΔX / ΔY / ΔZ.
- Pin — keep a measurement pair on screen.
- Exact B-Rep distances — not mesh approximations.
- Auto Measure — engineering dimensions laid out and toured.
- Inspect ▸ Mass properties — mass, volume, surface area, center of mass.
Tip: Pin the measurements that matter before an in-place edit, then watch them update when you Apply — a quick way to confirm the change did what you intended.
Ready to try it yourself?
Everything in this guide works in your browser — no install and no card required. Start on the free plan and build your first part.