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Model a desk robot arm: the assembly

The assembly puts the six parts together. Its parameters drive the joints, so posing the arm is changing a number. The fasteners come from the standard parts library: a hex bolt and a nut are inserted for each pivot and replicated onto its connectors, and Fasten fills every hole set with socket head cap screws, reading their size from the holes and sinking their heads into the counterbores.

Each step shows the Designer as you make it: a feature's dialog filled in with the step's values, with the tutorial card ringing OK, or what the step made. The first time a command appears, a picture shows where it is. The step numbers match the card's in Help > Tutorials.

  1. New assembly, from File > New assembly: name Desk arm.

    The assembly brings it together: parameters for each joint, the parts inserted (both links from one document at their own sizes), the joints with their limits, then the fasteners from the standard parts library: a hex bolt and a nut through each pivot, and Fasten filling every hole set with socket head cap screws.

    Model a desk robot arm: where New assembly is, ringed in its menu, the tutorial card ringing it on the toolbar too where it has a button
    Model a desk robot arm, step 97: New part made, and what it made selected in the panels

  2. Parameter, from Insert > Parameter: name yaw, value -35, unit deg.

    Add the parameter yaw, -35 degrees: how far the shoulder turns on the base.

    Model a desk robot arm, step 98: Parameter made, and what it made selected in the panels

  3. Change parameter, from the Properties panel: name yaw, min -170, max 170.

    Give yaw its range, -170 to 170 degrees: the values the design is drawn for.

    Model a desk robot arm, step 99: Change parameter made, and what it made selected in the panels

  4. Parameter, from Insert > Parameter: name shoulder, value 60, unit deg.

    Add the parameter shoulder, 60 degrees: the upper link's angle at the shoulder.

    Model a desk robot arm, step 100: Parameter made, and what it made selected in the panels

  5. Change parameter, from the Properties panel: name shoulder, min -10, max 120.

    Give shoulder its range, -10 to 120 degrees: the values the design is drawn for.

    Model a desk robot arm, step 101: Change parameter made, and what it made selected in the panels

  6. Parameter, from Insert > Parameter: name elbow, value -80, unit deg.

    Add the parameter elbow, -80 degrees: the forearm's angle at the elbow.

    Model a desk robot arm, step 102: the Sketch dialog filled in with the step's values, the tutorial card beside it ringing OK

  7. Change parameter, from the Properties panel: name elbow, min -100, max 100.

    Give elbow its range, -100 to 100 degrees: the values the design is drawn for.

    Model a desk robot arm, step 103: the Extrude dialog filled in with the step's values, the tutorial card beside it ringing OK

  8. Parameter, from Insert > Parameter: name wrist, value -40, unit deg.

    Add the parameter wrist, -40 degrees: the wrist's angle.

    Model a desk robot arm, step 104: the Sketch dialog filled in with the step's values, the tutorial card beside it ringing OK

  9. Change parameter, from the Properties panel: name wrist, min -90, max 90.

    Give wrist its range, -90 to 90 degrees: the values the design is drawn for.

    Model a desk robot arm, step 105: the Extrude dialog filled in with the step's values, the tutorial card beside it ringing OK

  10. Parameter, from Insert > Parameter: name grip, value 4, unit mm.

    Add the parameter grip, 4 mm: how far each jaw slides open.

    Model a desk robot arm, step 106: the Sketch dialog filled in with the step's values, the tutorial card beside it ringing OK

  11. Change parameter, from the Properties panel: name grip, min 0, max 11.

    Give grip its range, 0 to 11 mm: the values the design is drawn for.

    Model a desk robot arm, step 107: the Pocket dialog filled in with the step's values, the tutorial card beside it ringing OK

  12. Insert component, from Insert > Insert component: id base, part base.

    Insert the base at the assembly's origin. It is the one component no joint moves.

    Model a desk robot arm: where Insert component is, ringed in its menu, the tutorial card ringing it on the toolbar too where it has a button
    Model a desk robot arm, step 108: the Fillet dialog filled in with the step's values, the tutorial card beside it ringing OK

  13. Insert component, from Insert > Insert component: id turntable, part turntable.

    Insert the shoulder. Where it lands does not matter: the joint in the next step places it.

    Model a desk robot arm, step 109: the Chamfer dialog filled in with the step's values, the tutorial card beside it ringing OK

  14. Joint, from Insert > Joint: id yaw, component turntable, connector bottom, angle yaw.

    Put the shoulder on the base with a revolute joint, from its bottom connector to the base's top one. The yaw parameter is its angle, kept between -170 and 170 degrees.

    Model a desk robot arm: where Joint is, ringed in its menu, the tutorial card ringing it on the toolbar too where it has a button
    Model a desk robot arm, step 110: Part properties made, and what it made selected in the panels

  15. Insert component, from Insert > Insert component: id upper, part link.

    Insert the link as the upper arm, 160 mm between its pivots.

    Model a desk robot arm, step 111: Add connector made, and what it made selected in the panels

  16. Joint, from Insert > Joint: id shoulder, component upper, connector proximal, angle shoulder.

    Join the upper link's near end to the shoulder's pivot with a revolute joint, turned by shoulder.

    Model a desk robot arm, step 112: New part made, and what it made selected in the panels

  17. Insert component, from Insert > Insert component: id fore, part link.

    Insert the same link document again as the forearm, slimmer and shorter: length 130, width 14, gap 10, hub 13, tip 11. One document, two parts.

    Model a desk robot arm, step 113: Parameter made, and what it made selected in the panels

  18. Joint, from Insert > Joint: id elbow, component fore, connector proximal, angle elbow.

    Join the forearm's near end to the upper link's far end, turned by elbow, kept between -100 and 100 degrees, as far as the fork's seat lets it swing.

    Model a desk robot arm, step 114: Change parameter made, and what it made selected in the panels

  19. Insert component, from Insert > Insert component: id wrist, part wrist.

    Insert the wrist.

    Model a desk robot arm, step 115: the Sketch dialog filled in with the step's values, the tutorial card beside it ringing OK

  20. Joint, from Insert > Joint: id wristJoint, component wrist, connector pin, angle wrist.

    Join the wrist into the forearm's fork, turned by wrist.

    Model a desk robot arm, step 116: the Extrude dialog filled in with the step's values, the tutorial card beside it ringing OK

  21. Insert component, from Insert > Insert component: id gripper, part palm.

    Insert the gripper.

    Model a desk robot arm, step 117: the Chamfer dialog filled in with the step's values, the tutorial card beside it ringing OK

  22. Joint, from Insert > Joint: id mount, component gripper, connector mount.

    Fasten the gripper to the wrist's flange. A fastened joint holds it still.

    Model a desk robot arm, step 118: the Chamfer dialog filled in with the step's values, the tutorial card beside it ringing OK

  23. Insert component, from Insert > Insert component: id jawA, part jaw.

    Insert a jaw.

    Model a desk robot arm, step 119: the Hole dialog filled in with the step's values, the tutorial card beside it ringing OK

  24. Joint, from Insert > Joint: id gripA, component jawA, connector slide, offset grip.

    Put the first jaw in its rail with a slider joint. Its offset is the grip parameter, 0 to 11 mm.

    Model a desk robot arm, step 120: Part properties made, and what it made selected in the panels

  25. Insert component, from Insert > Insert component: id jawB, part jaw.

    Insert a second jaw from the same document.

    Model a desk robot arm, step 121: Add connector made, and what it made selected in the panels

  26. Joint, from Insert > Joint: id gripB, component jawB, connector slide, offset grip.

    Put the second jaw in the other rail, driven by the same grip, so both jaws open and close together.

    Model a desk robot arm, step 122: New assembly made, and what it made selected in the panels

  27. Standard part, from Insert > Standard part: kind bolt, standard iso, id shoulderBolt.

    Insert a hex bolt from the standard parts library as the shoulder bolt, M8 and 55 mm long. The library adds a Hex bolt part document, which the other bolts reuse at their own lengths.

    Model a desk robot arm, step 123: Parameter made, and what it made selected in the panels

  28. Replicate, from Insert > Replicate: id shoulderBolt, connector seat.

    Replicate the bolt onto the shoulder's boltFace connector. It goes through both hubs and the upper link between them.

    Model a desk robot arm: where Replicate is, ringed in its menu, the tutorial card ringing it on the toolbar too where it has a button
    Model a desk robot arm, step 124: Change parameter made, and what it made selected in the panels

  29. Standard part, from Insert > Standard part: kind nut, standard iso, id shoulderNut.

    Insert an M8 hex nut from the library for the shoulder bolt.

    Model a desk robot arm, step 125: Parameter made, and what it made selected in the panels

  30. Replicate, from Insert > Replicate: id shoulderNut, connector seat.

    Replicate the nut onto the shoulder's nutFace connector, on the other side.

    Model a desk robot arm, step 126: Change parameter made, and what it made selected in the panels

  31. Standard part, from Insert > Standard part: kind bolt, standard iso, id elbowBolt.

    Insert an M8 hex bolt as the elbow bolt, 35 mm long.

    Model a desk robot arm, step 127: Parameter made, and what it made selected in the panels

  32. Replicate, from Insert > Replicate: id elbowBolt, connector seat.

    Replicate it onto the upper link's boltFace connector.

    Model a desk robot arm, step 128: Change parameter made, and what it made selected in the panels

  33. Standard part, from Insert > Standard part: kind nut, standard iso, id elbowNut.

    Insert an M8 nut for the elbow.

    Model a desk robot arm, step 129: Parameter made, and what it made selected in the panels

  34. Replicate, from Insert > Replicate: id elbowNut, connector seat.

    Replicate it onto the upper link's nutFace connector.

    Model a desk robot arm, step 130: Change parameter made, and what it made selected in the panels

  35. Standard part, from Insert > Standard part: kind bolt, standard iso, id wristBolt.

    Insert an M8 hex bolt as the wrist bolt, 30 mm long.

    Model a desk robot arm, step 131: Parameter made, and what it made selected in the panels

  36. Replicate, from Insert > Replicate: id wristBolt, connector seat.

    Replicate it onto the forearm's boltFace connector.

    Model a desk robot arm, step 132: Change parameter made, and what it made selected in the panels

  37. Standard part, from Insert > Standard part: kind nut, standard iso, id wristNut.

    Insert an M8 nut for the wrist.

    Model a desk robot arm, step 133: Insert component made, and what it made selected in the panels

  38. Replicate, from Insert > Replicate: id wristNut, connector seat.

    Replicate it onto the forearm's nutFace connector.

    Model a desk robot arm, step 134: Insert component made, and what it made selected in the panels

  39. Fasten, from Insert > Fasten: length 10, id baseScrews.

    Fasten the base to the desk: Fasten reads M5 from the holes on the base's bolts connector and puts a socket head cap screw, 10 mm long, in each of the four, its head down in the counterbore.

    Model a desk robot arm, step 135: Joint made, and what it made selected in the panels

  40. Fasten, from Insert > Fasten: length 8, id palmScrews.

    Fasten the gripper's cover screws, M3 by 8 mm, one in each corner.

    Model a desk robot arm, step 136: Insert component made, and what it made selected in the panels

  41. Fasten, from Insert > Fasten: length 10, id jawScrewsA.

    Fasten the first jaw's two screws, M3 by 10 mm.

    Model a desk robot arm, step 137: Joint made, and what it made selected in the panels

  42. Fasten, from Insert > Fasten: length 10, id jawScrewsB.

    Fasten the second jaw's screws the same way.

    Model a desk robot arm, step 138: Insert component made, and what it made selected in the panels
Model a desk robot arm, after step 167

Move the arm​

The joints read five parameters of the assembly: yaw, shoulder, elbow and wrist in degrees, and grip in millimetres. Each has a range, so select one in the Features panel and drag its slider in Properties: the arm moves while you drag.

Select a link component to give it other values for its document's parameters, such as a longer length. Both links come from one document, and each keeps its own values.

What you made​

  • Parts that reuse documents. The screws are one document inserted many times, each at its own diameter and length, and both arm segments are one link document at two sizes.
  • Connectors. Every place a part attaches is a connector on a face or a hole. Joints and replicates name connectors, not coordinates, so they follow the parts when sizes change.
  • Joints with limits. The turntable, the shoulder, the elbow and the wrist turn about their axes and the jaws slide, each within the range its joint allows, while the gripper is fastened to the wrist.

How the Designer works explains documents, connectors and joints in more depth.

Verified against the product in October 2026