Expert: Brian Mazejka - 9/5/2008

Question
I am trying to create threads on a screw, bolt and also a nut.  How do I do this?  I am very new to SW and am using SW 2008 Office Premium.  Any suggestions would be greatly appreciated!

Answer
Hi Janice,

Sorry I didn't respond sooner, but I didn't check my email over the weekend and just saw your question today for the first time.

OK ... creating threads on a part is a relatively easy thing to do.  A word of caution though even though a screw with actual threads looks pretty cool in an assembly it can also slow your computer down significantly if you use a lot of screws in an assembly.

For this example, I'll be creating a 10-32 x 1.00" screw).

If you want to create a realistic screw thread then make sure you read a Machinery's Handbook to gather all the correct dimensions such as thread depth, thread pitch, min & max thread height, etc.  For my example I'll just use some basic dimensions such as my thread pitch will be .03125" (32 threads per inch = .03125 pitch), thread height will be .1900 and the root diameter will be .1508.

Using the Front Plane - Create a solid rod in SWx .1508 diameter x 1.00 long (extrude the rod in the negative Z direction)

Start a new sketch on the front plane again, and convert the edge of the rod you just created.  Rebuild

Now select that sketch and then click on INSERT, CURVE, HELIX/SPIRAL ...

From here you'll be able to define the helix that will be used to create your thread.  You need to define the Height and Pitch (1.00" long x .03125 pitch).  Make the START ANGLE 90-degree's.  Click on the Green Check-Sign

Now view your part from the right side ...

Select the side plane and open a sketch ... create a triangle and make the bottom of the triangle collinear with the top of the solid-rod ... and the left point of the triangle coincident with the front-plane.

Now add a dimension from the center of the rod to the top point of the triangle and make it .095 (thread diameter .190 / 2 = .095) ... and make the base of the triangle .029 (I chose this number arbitrarily ... this dimension should be less than the actual pitch you made the Helix/Spiral ... if it isn't, then the system can't create the thread).

Now with your Triangle Sketch and Helix/Spiral done, select the Features Tab and click on the SWEEP icon.  The first thing to select is the Profile (Triangle) and the next thing to select is the Path (Helix/Spiral).

So you should have a threaded rod.  From here, there will be some clean up necessary, like adding the head of the screw, chamfers, etc. ... but that's the basic approach to creating threads.

To create threads on a bolt use the same approach only use an inverted triangle.

If you need more assistance, please feel free to ask me more questions.

Good Luck,
Brian