Perfect Threads


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I've been trying to figure out a way to taper the last little
bit of thread without doing it one section at a time.

This one nearly made me loose what little sanity I have left.
It's still a work in progress but trying to orient
the splines for a Sweep made me crazy.

I got the splines directly from a section of the threads I Split from
the model using Hiroto's Polygon to Spline script. @tg_jp

Here's my progress on the head end of the Sheetrock screw.

Sweep taper splice.jpg


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Here's the final one inch Sheetrock screw.

After making the Phillips head, I checked the Object Info to find it was not watertight.
Even though I was very careful, the Optimize Tool had welded some vertices in the tip.

The tip tapering process should be done last as almost any setting
of the Optimize Command will produce holes in the mesh at the tip.

At first I was :mad: but then :unsure: and then I realized it was :cool:.
I just had to Boolean trim the tip off and re-taper.

Sheetrock Screw 1inch.jpg


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Here's another thread build with no subdividing at 64 sections radially for a larger diameter threaded cylinder.
I wanted to show a technique for setting the height of the threads. This makes it easy to measure such things.

The Transform Gadget got an upgrade a while ago: Position Parameters, I'm starting to rely on these more and more.



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The previous technique is useful after beveling the thread tip because this reduces the thread height.



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After all this I haven't mentioned inside threads.

The Wrap Modifier can simply be rotated 180 on the Y axis for the body of the thread.
For the lead in thread section you also have to rotate the polygons on the Z axis 180.

I had more trouble making the embossed text than making the threads.
64 radial sections 17,517 polygons.

Threaded Bushing.jpg


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For the next attempt I decided to take it to the next level.
I wanted to make threads that could be 3D printed and work with existing fasteners.
I don't have a 3D printer yet, but I would love to get one so this is just preliminary testing.

These are the most accurate threads I could make.
I also use the method from earlier to make all quads.

Here's a close up of the Taper Modifiers very precise placement to taper the lead in thread.
Set to the type- "In Cage" I evenly scaled the Modifier around the Y axis to keep it square.
(Hold the shift key while dragging on the Y scale cube of the Transform Tool)
And then I adjusted the "Cage" to affect all but the very outer edge.

Blue lines = Modifier
Pink lines = Cage



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I made this GIF to illustrate the thread position relative to a drilled hole.

All machine threads have a flat peak. Inside threads have a flat peak
width 1/4 of the peak to peak measurement defined as P.
Outside threads have a flat peak 1/8 of P.



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This one is just over 6k polygons but I added a Subdivision Modifier set to 1 iteration for closeups.

Real Perfect thread.jpg

RPT Cutaway comp.jpg


I have to admit that I have never seen a thread like this and I don't know any tool to make it like this. All my taps cut directly into the surface whether metal or wood.
This one is made of the finest dark chocolate with 75% cocoa content:


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You're absolutely correct, the tapered lead in thread was a way to make all quads but doesn't exist in the real world.

I would grind a little beveled edge after tapping a hole to make it easier to screw in a bolt.

We call it tapping a hole, do we call it die-ing a bolt?


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This time I shortened the tapered edge to look less weird.

I also tried partially Catmull-Clarking to make more geometry for knurling.
It's still watertight and renders great. As long as tris and n-gons
are only on flat areas I usually get good results.



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Today I decided to do some macro photography of some plastic molded threads.
I spent most of the day waiting for the camera battery to charge.

My previous statement about the tapered lead in thread not existing was wrong,
molded threads do have this and here's a garden hose fitting in plastic,
close up... and real close up.

Molded Threads.jpg

Molded Threads 01.jpg


That's funny because I noticed the same thing yesterday evening as I was taking a photo from a real wooden thread I made - having a beer. In plastic all is possible of course but not in cutting technology where you drill a hole and cut a thread accordingly.