How do you make nuts and bolts, worm drives, screw threads...?

[John_H555]

Cutting threads is a common problem but it is difficult to search for solutions, since the word "thread" is such a common term of art on the internet.  I found four links about it, here, but I confess I can't make much sense out of them:

http://www.rhino3dhelp.com/forum/index.php?topic=433.msg1451#msg1451

http://offbroadway.blogspot.com/2007/01/internal-screw-thread.html

http://offbroadway.blogspot.com/2007/01/screw-thread-tutorial.html

http://offbroadway.blogspot.com/2006/12/screw-thread-tutorial-1-draw-shape-of.html

Is there a Rhino3D plug-in that draws nuts and bolts and screw threads? 

So far, using RailRevolve and a simple thread profile, I have been able to draw a helical thing that looks like a thread.  However it does not have a proper beginning and end, and I cannot seem to integrate it with a cylinder representing a bolt. 

Many thanks for your insights or links.

John

[Ivan]

http://www.rhino3dhelp.com/tutorials/modeling-light-bulb/3/

I think this would be helpful. It is easy to create a thread, but that integration is usually pain in the ass. Check out the tutorial how I did it. If anyone has any other way of doing this, I'd be more than happy to hear it out. This is my only method so far.

As for the plugins, never heard of one.

[John_H555]

Thank you Ivan, the tutorial is very helpful.  I have also found it helpful to watch videos of actual thread cutting operations on lathes.  Here is an example:

http://www.youtube.com/watch?v=0q_q53wsyHU&feature=related

Notice the way the blank cylinder has been prepared with a 45-degree face at the beginning and end of the screw thread.   My thought is to replicate the blank in Rhino3D as a first step, and then do a Boolean using a separately formed thread pattern created with Helix and Spiral. We'll see.  Thank  you again. John.

[John_H555]

Here is a series of screen captures to illustrate one method for thread cutting. It is based on watching YouTube videos of thread cutting operations as carried out on machine lathes.

 The illustrations labeled "before Boolean" and "threads & blank" show what I was working toward in Rhino. 

I am thinking of the lathe cutting tool as a sort of paintbrush that leaves behind a V-surface that follows the path of a helix.  At the shaft end of the helix, as the cutting tool retracts, the radius of the helix expands into a spiral.  You may need to scroll these images to the right to see the part of the thread where it spirals out from the diameter of the basic helix.

 Once the spiral and helix are formed and joined (Using Spiral and Helix in Rhino), a thread profile is pinned to the beginning of the helix.  This is then transformed into the V-surface using RailRevolve.

The front of the blank is beveled at 45 degrees.  Also notice that the thread profile has been extended (with Extend), so that the depth of the "V" is exaggerated.  This is because the Boolean operation, to follow, works better if there is a good overlap between the spiral surface and the surface of the machined blank. 

The example used here is a model of a component used in a 19th century steamship. 

John

[lmcdesign]

looks like you got it.