Procedurally modeling threads

[Pancho]

This has always been a nightmare for me when doing this in Modo. I need to maintain a nice subdivision geometry. Quads are mainly what I want, but tris will be fine, too. The point is, to create a helix with the thread itself is no problem, but to "melt" it with the geometry above and beneath (e.g. on a jar or bolt) is horrible and always kept my busy in order to find a nice polyflow and manage the transition.

 

Since I need to model a lot of packaging soon, this will be an issue. At least it will take a lot of time.

I wonder: Is there a nice convinient way to solve this in Houdini? In the end I would need a certain profile for the thread and an angle in degree how often the thread is winding around the y-axis.

 

I searched on the forum for thread but didn't find any posts. Anybody how can point me to a solution? Guess it's quite a common task.

 

Cheers

Tom

[fathom]

not sure what you mean by "melt" it with the geometry above and beneath.

 

for a thread/rope i would opt for a displacement shader on a nurbs tube unless you're wanting to see individual fibers floating off the thing.

[mestela]

Took me a moment, I think he's talking about the thread on a screw/bolt/lid/jar, not thread as in fibre. 

[fathom]

derp.  yeah, makes more sense now. 

 

yeah, to keep the poly flow, i'd aim to generate the non-threaded portion from the same basic topology as the threads themselves.  so think of a tube that's evenly subdivided.  thread one portion of it by twisting and sawtoothing it and then make a bolt head by flaring and flattening.  you'll probably have "too much" poly detail in the bolt head portion, but i'd think that's better than monkeying around with merging disparate topologies.  unless you just jammed the threaded section to a hex block and didn't worry about the blend.

 

the nice thing about houdini is that if you do it with vops and not direct editing, you can always change your base resolution if you need more/less rez to make things work.

[Pancho]

Here are two screenshots from a model I did some while ago. Beneath the thread is clean topology (horizontal edge loops). The geometry inbetween is a helix. My problem is, since the geometry of the thread profile will differ, how to generate the topolgy between the rest of the jar (in this case) and the helix, so that I get a clean and smoothly subdivided mesh. Of course this can be done manually, but I guess in Houdini there should be some ways to do this more efficiently, especially if you need to do this often.

 

Cheers

Tom

[Pancho]

Just on the side. In this case I modeled the thread linear (all on the same z-axis) and bent it afterwards into it's circular shape. Maybe this helps to get some ideas.

[konstantin magnus]

here is a procedural approach:

screw.hipnc

Edited January 28, 2016 by konstantin magnus

[Pancho]

Thanks for the input!!!