Is it possible to build a perfectly spherical prince Ruperts drop (2015) | Hacker News Reader

Is it possible to build a perfectly spherical prince Ruperts drop (2015)

engineering.stackexchange.com

49 pointsnadermx18 comments

You can apparently melt the tail off, and the resulting drop remains strong: https://www.youtube.com/shorts/gjrqwUeAk8Y

Is that still the same thing afterward?

It survives a few timid taps with a hammer, which isn't impressive (regular glass beads can do this).

It then also survives having the remains of the tail cut off with snips, which is a thing that Prince Rupert drops do not survive -- as a rule.

If I had to guess, then I'd guess that heating it and cooling it relatively slowly (as shown in the video) has somewhat annealed it, and thus converted a Prince Rupert drop into a regular slug of glass.

But the nose was not heated

The "nose" was only not heated if glass is a perfect insulator. But glass is not a perfect insulator.

And as-shown, a lot of that "nose" was glowing-hot after being hit with the torch, and none of it was subsequently quenched in water (as Prince Rupert drops are by definition).

For those on desktop wanting their video controls https://www.youtube.com/watch?v=gjrqwUeAk8Y

Just saw a video of a prince rupert's drop breaking a hydraulic press and wondered the same.

I was under the impression that the plates on those presses were usually hardened, hardened steel would never deform like that it would fracture so they might have made some choices there for show that wouldn’t have normally happened.

As I understand it, those are used so that the press itself doesn't get worn out, and come in various types.

Do you have a link to the video?

https://youtu.be/vZh_XSQ5WVU

Really fascinating. I knew you could smack them with a hammer, not that it would deform a steel press.

After adding titanium plates, it finally broke at 10 tons. Super impressive.

Those press tools appear to have been made from some something other than steel. (Maybe aluminum or zinc, given the cheese-like results with only ~10 tons.)

Here's the OG HPC crushing a Prince Rupert drop with a hydraulic press and steel tools: https://www.youtube.com/watch?v=OCJwHrvutGk

At 3:20, the deformation of the tools is shown after they have put 29 tons onto a Prince Rupert drop: There's a good dent, but not like they were made from Mozzarella.

(Later in the video are more demonstrations, peaking at around 68 tons, that also do not turn the press tools into cheese.)

Instead of trying to cool the surface of the glass sphere rapidly, maybe it would be more practical to heat the interior.

You could start with a plain glass sphere, then soak it in the same molten salts they use to make Gorilla glass, for a day.

Tempered class is made using similar process. What is the strength difference between Ruperts drop and best bulled proof class?

It is annoying that there is not actually a good answer anywhere in there

Yes there was? The first one described it

the replies to that seem to indicate otherwise

The short answer is yes, you can make a tempered glass sphere. Lots of things are made of tempered glass.

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