How often do you need to model a working threaded screw? "Not very often"- you might say. And while I agree with you, I'd like to show you how to model one anyway because I think there are some really important modeling concepts to be learned here.
This tutorial assumes you know at least basic modeling techniques in Maya.

Create a polygon helix using the default settings. To make sure it is on default, open the Create Helix option box, then select Edit>Reset Settings. This will create a helix with a lot of polygons.



Too much, right? Yeah, most of the time this is way too many tris. Reduce the number of Subdivisions Coil to any number of your choosing, but I would recommend a number that creates a perfect '+' sign when looking down on the object (such as 16).



You might notice the coils are crashing into eachother. That's ok. You'll end up with something like this:


Now we need it to be 'screw-like'. Right now is it like a spring, but we're looking for something that is threaded. First go to the Inputs section of the helix's Attribute Editor. Change the Height to 1.7. Now the coils have lined up almost perfectly and we can start to see the makings of a threaded screw.


There's a bunch of geometry we don't need in the middle that we're going to get rid of. The easiest way is to go to the top view and use Lasso Select tool to select the faces we don't want which is all of the face except the outer ring like this:


Delete! Now all we need to do is merge the points were each thread meets the one below it. Select all the vertices. The select Edit Mesh> Merge option box. Set the threshold to .009; that should merge all the points you want and ignore the ones you don't.

Now you're done! Well, not really. To make it a real screw, you have to scale it down vertically and also duplicate and merge it a few times.


I quickly finished this one off like this:

And I made one like this last year:


I hope you found this tutorial helpful, thank-you for reading.