Needing help with identifying this thread.

[Murdoch]

Hello everyone.
It's been a while, I have a problem identifying this thread.
The image is a screenshot of Steve Austin's bionic eye, from the six million dollar man. I am hoping to recreate many of the props from the TV series and originally I thought this was a 5/8 thread, but the diameter seems too narrow.
I'm hoping to get answers before I jump the gun and get a 5/8 acrylic rod.
I would like to thank you all in advance...

 

[Mcgyver]

Using the thumbnail width as a gauge, I'd guess 5/16 or 1/4.

 

[Susquatch]

I think what makes it look weird is that it appears to be a double thread, but not quite. Which is of course not possible. It has to be one or the other. It is NOT triple.

Try to use your imagination to turn it into single thread and then a double. Whichever is easiest to do is probably correct. But don't forget that the characters who make those props love to play with your mind. That's what turns their crank. So it might just be an optical illusion.

 

[RobinHood]

That is just an optical illusion.

Acrylic has a different refraction index compared to air (which is what most of the light is travelling through to get to the part). Once the light hits the OD of the acrylic, it bends, thus making the thread appear different inside the part vs outside.

I would identify the thread size on the outside and cut the whole stub the same. Assemble, and I bet you will get the exact same look as shown in the screen shot.

 

[Murdoch]

I think what makes it look weird is that it appears to be a double thread, but not quite. Which is of course not possible. It has to be one or the other. It is NOT triple.

Try to use your imagination to turn it into single thread and then a double. Whichever is easiest to do is probably correct. But don't forget that the characters who make those props love to play with your mind. That's what turns their crank. So it might just be an optical illusion.

I did a close measurement and I believe it is actually a 1/2 inch diameter but the thread is larger.

 

[DPittman]

That is just an optical illusion

Pun intended?