Sketch to solid

A sketch describes intent

A circle placed by eye can move in two directions and change radius. A circle whose center is fixed to the origin and whose diameter is specified has those choices removed. Constraints express the design: coincidence says two points share a location; concentricity aligns centers; dimensional constraints set size. The solver finds geometry that satisfies the rules.

Fully constrained does not mean good engineering. You can fully constrain the wrong hole diameter. Conversely, leaving a useful degree of freedom during exploration can be intentional. For this first part, constrain all intended size and position choices so accidental dragging does not change the design. Avoid using a blanket lock as a substitute for understanding each dimension.

Features form a short, readable recipe

We will make a practice spacer with a 24 mm outside diameter, 6.6 mm through-hole and 4 mm thickness. These are exercise dimensions, not an approved BDX-R fastener interface. A Pad adds thickness to the outside circle. A second sketch and a Through all Pocket remove the center. The Body groups the resulting component and its operations.

The order matters because each feature uses geometry built earlier. Naming the sketches and features helps you find the correct input later. As models grow, stable references such as origin planes and named dimensions reduce surprises. A sketch attached to a face can be convenient, but substantial upstream edits can change which faces exist; inspect the result after every change.

A fixed-depth Pocket removes material only to the depth you enter. A Through all Pocket removes material through the entire component in the chosen direction. If you later increase this spacer’s thickness, Through all keeps the center opening as a through-hole; a shallow fixed-depth cut could leave material at the far end. Neither option chooses the hole diameter or proves the fastener will fit.

A hole has a purpose beyond its appearance

A clearance hole lets a fastener pass through; a tapped hole engages a thread; a press fit and a sliding fit have different requirements. A 6 mm nominal screw label does not mean every mating hole should be exactly 6 mm. Required clearance depends on the joint design, manufacturing process and relevant specification.

A spacer may look simple, yet its load path matters: which faces clamp, whether the fastener bottoms out, whether the material creeps and whether the hole is concentric enough for the job. We are practicing modeling and verification here. Do not substitute the practice spacer into a loaded robot joint merely because it exports successfully.

Export is another transformation to verify

Save the native document first. Select the intended Body or final feature when exporting; selecting the whole tree can include earlier or duplicate geometry. STEP carries exchange geometry, while STL approximates surfaces with triangles. Coarse tessellation can make a circle visibly polygonal; extremely fine tessellation increases file size without automatically improving a manufactured part.

Reopen exports in a new document and inspect dimensions, holes and object count. STL has no explicit unit declaration, so confirm the importer’s assumed unit. A mesh that displays at the wrong scale is still a valid file; validation must include the intended physical size, not only whether software can open it.