Model a desk robot arm: the screw

Every bolt and screw in the arm is this document. Its sizes are expressions of d and length, so the assembly can insert it at any diameter and length it needs.

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.

97. New part, from File > New part: name Screw.

    A socket-head screw, parametric in its diameter and length, so every bolt in the arm is this one document.

    

98. Parameter, from Insert > Parameter: name d, value 8, unit mm.

    Add the parameter d, 8 mm: the screw's diameter.

    

99. Change parameter, from the Properties panel: name d, min 2, max 20.

    Give d its range, 2 to 20 mm: the values the design is drawn for.

    

100. Parameter, from Insert > Parameter: name length, value 40, unit mm.

     Add the parameter length, 40 mm: how long its shank is.

     

101. Change parameter, from the Properties panel: name length, min 4, max 120.

     Give length its range, 4 to 120 mm: the values the design is drawn for.

     

102. Sketch, from Insert > Sketch: id shank, on the XZ plane.

     Sketch the shank on the ground plane: a circle d across.

     

103. Extrude, from Insert > Extrude: id screw, profile shank, distance length.

     Extrude the shank length tall.

     

104. Sketch, from Insert > Sketch: id crown, on the XZ plane.

     Sketch the head on a plane at the shank's top: a circle 1.6 d across.

     

105. Extrude, from Insert > Extrude: id head, profile crown, distance 0.7 * d, body screw.

     Extrude the head 0.7 d and join it to the shank.

     

106. Sketch, from Insert > Sketch: id hex, on the end face of head, start 0.3 * d, 0.

     On top of the head, sketch the hexagon of the key socket.

     

107. Pocket, from Insert > Pocket: id drive, profile hex, body screw, distance 0.4 * d.

     Pocket the socket 0.4 d deep.

     

108. Fillet, from Insert > Fillet: id round, body screw, radius 0.08 * d.

     Round the head's top rim.

     

109. Chamfer, from Insert > Chamfer: id lead, body screw, distance 0.1 * d.

     Chamfer the tip of the shank, so the screw finds its hole.

     
     

110. Part properties, from the Properties panel: id screw, name Screw, material steel, color #1d1f22, metallic 0.85, roughness 0.35.

     Name the part Screw: black steel.

     

111. Add connector, from Insert > Add connector: part screw, id seat, on the start face of head, axis the side face of screw.

     Add a connector under the head, its axis along the shank: where the head sits on what it holds. Replicating the screw onto a connector on a set of holes puts one copy in each.