Rhino Screw Thread Tutorial

1. Draw a _Line slightly longer than your screw shaft.
2. Use _Curve to draw the profile of your shaft. I have left the _Points showing so that you can see where I placed them. The three points close together control the transition from the straight section to the curve.
3. _Revolve the curve around the line at (1) and use _Cap to create the solid.
4. Draw a _Helix around the original straight line at (1)(the central axis)
5. Draw a line between the tip of the end of the central axis (1) and the end of the helix (4)
6. Sweep2 the line (5) between the axis (1) and the helix (4)
7. In the drop-down Curve menu, choose 'Curve From Objects'. Select Intersection and pick the shaft and the helical surface.
8. _Delete (or _Hide) the helical surface.
9. _Copy the intersection curve in line with the axis (1) by the width of the tooth.
10. Draw the tooth profile between the end points of the two intersection curves (7, 9)
11. _Copy the tooth profile to another point between the curves (7)
12. _Sweep2. Pick the two curves (7, 9) and each of the tooth profiles (10, 11) in the order created, then type P and pick the end of the curve (7) at the tip. This will cause your Sweep2 to create swept surfaces along the curves using the profiles as placed. The P option will then cause the profile to taper to the tip. _Cap the open end.
13. Create a head to suit.
14. In this example the inner face of the tooth profile lies exactly on the surface of the shaft. This can cause problems in boolean functions. I have had to cheat in this case by slightly scaling down the diameter of the thread. This is done by SCALENU. I defined 0.99 for the X and Z axis and 1 for the Y axis.You will need to consider this sort of adjustment when you plan the dimensions of a real project.

_BooleanUnion all together and delete the construction curves. NB: If you managed to get as far as the head, I believe you will be able to create a suitable solid yourself.

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