Perfect Threads

[ZooHead]

Modeling threads in Cheetah 3D is not hard, but there are so many different ways to proceed.
Every time I've done it, I've tried various methods to deal with
the triangle or triangles left over at the end of the spiral.

What if you could send that edge back down the spiral or redirect,
recycle and re-purpose it as well as keeping all quad construction.

When you see it, it's so obvious and simple. How did I not figure this out before?
Here's how it looks:

Adding a ring cut to control the edge at the base of the thread.

With a Sub Division Modifier Level 3.

I'll post the steps soon...

 

[ZooHead]

Here's a four part tutorial that should illustrate the steps.

After using Cover And Normal Move on the selected polygons, use Normal Scale to create the taper.

 

[ZooHead]

If you want to get more accurate here's a very helpful public domain chart.

 

[MonkeyT]

Here I go getting needlessly obsessive again, but the only question I have left is plumber's threads. The threads used on most plumbing fixtures are actually designed to tighten as you affix them - this allows merely screwing on a connection to tighten it to the point that water shouldn't leak instead of letting the nut ride up the entire length of the cut threads. It's practically invisible without a microscope, so it's really not very important, I was just wondering if the build techniques you laid out could accommodate threads that swell in thickness as they travel?

 

[ZooHead]

NPT National Pipe Thread also stands for National Pipe Taper.
I'll have to think about that, I've never tried before.

There are a few oddball standards like buttressed threads, like the ones on my Nalgene bottle.
Some are straight inside and tapered outside for special applications.

 

[ZooHead]

You can use a Taper Modifier on the tube before you push out the threads.
And don't use Normal Move when you do, use the Transform Tool
and scale out radially with the shift key.

First try is pretty close although the valleys should be narrower.

 

[ZooHead]

Here's another tapered thread I went a little nuts on.

 

[uncle808us]

You are very talented in this type of 3D modeling.

 

[ZooHead]

Thanks Unc, I love doing this type of object.

 

[ZooHead]

It's possible to work on threads symmetricly.
The symmetry is not mirrored, so the Mirror Tool and the Symmetry Modifier won't work.
But you can use the Ring Modifier in situations like this.

 

[jdmac]

@ZooHead , thanks for the tutorial!

 

[ZooHead]

@ZooHead , thanks for the tutorial!

My pleasure!

 

[ZooHead]

For a while now I've been thinking about making threads starting with a rectilinear form.
I found the Wrap Modifier to be a very powerful tool for this.
With it you can change the diameter without changing the thread angle.

 

[ZooHead]

After some testing it seems plausible to create a "Thread Panel" library by threads per cheetah unit for every thread.
You could have separate panels for the ends and the body. Since the diameter can be infinitely adjusted and larger
diameter threads should have more sections, separate panels can be made for small and large diameter forms.

 

[silaeb]

Smashing ! ^^

 

[ZooHead]

If anyone is interested in this method here's a jas file showing a 20 tpi thread panel being
used to make a 2 inch long section of 1/4" 20 threads plus the ends pieces.

The real star tool hear isn't the Wrap Modifier, it's the Ring Modifier.
I used it to double the length of the thread panel as well
as placing the end pieces with it's offset parameter.

 

[MonkeyT]

It's nice to see a project that starts as "a solution in search of a problem" evolve into a beautifully comprehensive cure for a well defined issue! I have definitely bookmarked this one.

 

[ZooHead]

@MonkeyT Thanks, I guess I'm good for one more for the wood/sheet metal screws.
Adding the spline/extrusion step suggested by @EllenM.

Notes:
• Wood screw - This type of screw ends in a sharp point, so there's little hope of an all quad object.
• Wrap Modifier - Leaves a visible seam, until made editable and optimized to weld polygons together.
• Threads per cheetah unit - Who the hell knows. Coarse and fine. Pending further measurement.

 

[jdmac]

• Threads per cheetah unit - Who the hell knows. Coarse and fine. Pending further measurement.

"Threads per cheetah unit" ... is that a new ISO 10844 standard

 

[ZooHead]

TPU joins other dimensionless measurements such as the angle.