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Unit 05 · Lecture 10

Motion constraints, Content Center and Insert

This lesson completes the tapping mechanism. You add the moving parts, tell Inventor how they drive each other, and bolt everything together with standard screws from the Content Center.

Video 21:34Reading 10 minUpdated 26 October 2026

Lecture video, 21:34. The written steps below follow the video, with timestamps for each part.

What you will build

The complete tapping mechanism: bearing blocks, short bolt, Kurbel (crank) and pin, Pleuel (connecting rod), lock pins, lever, bolt, pin marker and four M4 × 12 socket head screws. Rotating the short bolt drives the whole linkage.

You will learn

  • Reading the parts list for item numbers and quantities
  • Rotation-rotation motion constraints, ratios and direction
  • Using Measure to decide fit and orientation
  • Place from Content Center
  • The Insert constraint with Lock Rotation

Before you start

Start from the assembly in Lecture 9, with the ground plate grounded and both rail stands constrained.

Step by step

  1. 01

    Use the parts list as your checklist

    0:00

    The assembly drawing’s parts list gives each item’s number, name and quantity. Place the half bearing block (item 3), rotated X 90°. Mate its bottom face to the plate, then align the hole axes. A snapping sound confirms each constraint.

  2. 02

    Short bolt and crank

    1:28

    Place the short bolt, mate its head face to the bearing block and align the axis. Leave rotation free, because this part drives the mechanism. Keep it horizontal (Ctrl+Z if you spun it). Place the Kurbel part, mating the ridged side as the drawing’s top view shows (shortcut C for Constrain).

  3. 03

    Tell Inventor the parts turn together

    4:19

    Rotating the bolt doesn’t move the crank yet, because assembly constraints only position parts. Open Constrain → Motion → Rotation-Rotation, pick the back faces of the bolt and the crank, set the ratio to 1 and the solution to Forward. For gears, the ratio is the gear ratio.

  4. 04

    Pin and connecting rod: measure the fit

    6:24

    Place the Kurbel pin flat side to the front and use Flush, then the axis. For the Pleuel, use Measure: the pin is Ø4, and the rod’s holes are Ø4 and Ø5. The Ø4 hole goes on the pin, so orient the rod with the larger hole at the top. Flush its back face behind the pin’s groove, which is where a washer would sit.

  5. 05

    Lock pins, lever and bearing block

    11:35

    Item 8 has quantity 2, so place two lock pins. Mate them to the rod, then constrain the lever to both with Flush and axis. Add the bearing block (rotate X, then Y).

  6. 06

    Let the lever settle

    14:43

    Align only the lever’s axis with the bearing block holes. The lever then swings into place, just as it would if you pulled it into line by hand. Secure it with the bolt, and flush the pin marker axially with the short bolt. Rotate the short bolt and the whole linkage moves.

  7. 07

    Place screws from the Content Center

    16:58

    Screws and washers aren’t modelled parts. Use Place from Content Center, search DIN 912 (now DIN EN ISO 4762), choose M4 with a nominal length of 12, and place four copies.

  8. 08

    Insert with Lock Rotation

    19:08

    Mate plus axis lets a screw spin. Use the Insert constraint instead: pick the screw head edge and the hole edge (edge and axis in one pick) with Lock Rotation on. The screw then has no degrees of freedom.

Positioning vs. motion

Two kinds of constraint

Assembly constraints (Mate, Flush, Insert) say where parts sit. Motion constraints say how one part’s movement drives another. A linkage needs both.

Standard parts aren’t modelled

Bolts, screws and washers come from catalogues by standard number. The Content Center holds them, so you pick DIN 912 M4 × 12 rather than drawing a screw.

Common mistakes

Practice exercise

Change the rotation-rotation ratio to 2 and rotate the short bolt. The crank should turn twice as fast. Set it back to 1, then add DIN 127 spring washers under the screws from the Content Center.

Check yourself

Which constraint type makes one part’s rotation drive another?

Motion → Rotation-Rotation.

What does a ratio of 1 mean?

One turn of the driver gives one turn of the driven part.

Where do you get a DIN 912 screw?

Place from Content Center.

Which constraint seats a screw and stops it spinning?

Insert with Lock Rotation on.

Want the graded version? Take the 5-question lesson quiz in the course player after the video.

Written by the CADsmit instructor from the lecture recording and checked in Autodesk Inventor Professional 2027. Last updated 26 October 2026. Spotted an error? Tell us.