A herringbone gear with a D-bore
A gear drawn with two clicks, extruded with a twist, bored with a D for a shaft, chamfered on every tooth by one revolved triangle, and mirrored into a herringbone. Seven steps: the Gear tool, twist, a through cut, revolve-subtract and a mirror pattern.
7 steps
What it builds
- Sketch
- Extrude
- Cut
- Revolve
- Mirror pattern
Step 1
Sketch the gear
Create a sketch on the base plane and pick the Gear tool. Click the origin for the centre, then a second point about 20 mm out: that click sets the pitch radius and which way the first tooth faces. The tooth count is not typed — it follows from the pitch radius and the module line the tool adds beside it.
Step 2
Extrude it 5 mm with a 10° twist
Leave the sketch, select the gear and Extrude it with Distance 5 and Twist 10. The profile rotates ten degrees as it rises, so every tooth becomes a slanted helix — a helical gear runs quieter than a straight one because each tooth engages gradually.
Step 3
Sketch a D-shaped bore on the top face
Click the top face and start a sketch on it. Draw a Circle at the centre, 3 mm to the rim, then a horizontal Line across it 2 mm below the centre, from rim to rim — its two ends snap onto the circle. The line splits the circle into a big D and a small sliver: the flat is what stops a shaft from spinning in the bore.
Step 4
Cut the D through everything
Leave the sketch, select the big part of the circle (above the flat) and pick Cut. Set Up to to Through all so the bore goes out of the bottom whatever the gear's thickness becomes later.
Step 5
Sketch the chamfer profile on the XZ plane
Create a sketch and this time pick the XZ plane — the vertical one, which sees the gear edge-on. Out at the tooth tips, at x ≈ −23, draw a right triangle with three Lines: a horizontal top edge at z ≈ 7, a couple of millimetres clear of the gear's 5 mm top face, a vertical edge down the outside to z ≈ 2.15, and the 45° hypotenuse back up. About 4.8 mm a side. Only the hypotenuse decides what gets cut, so letting the triangle stand proud of the gear costs nothing — and it gives you a band to click on in the next step.
Step 6
Revolve it away: a chamfer on every tooth
Leave the sketch and click the triangle where it rises above the gear's top face — the rest of it is buried in the solid, and a region behind material cannot be picked. Then run Revolve: the Axis is the world Z axis (the gear's own), the Angle stays at 360, and Combine must be Subtract. The triangle sweeps a cone that shaves the tip of every tooth at once — a chamfer on twenty-odd teeth with one feature.
Step 7
Mirror it into a herringbone
Double-click the gear to select the whole body and pick Mirror pattern. For the Plane choose the world XY plane — the small blue square at the origin, or the gear's bottom face, which lies on it — and turn on One body. The copy hangs under the original with its twist reversed, and the two meet in a V at the seam: a herringbone. The opposed helices cancel each other's sideways thrust, so this gear needs no thrust bearing.