Old video about quartz crystals manufacturing.

[firewalker]

Alexander.

[VK3DRB]

Thanks, very interesting!

Making crystals in the war years seemed incredibly tedious due to the lack of automation that we use these days. What is of note is the women looked really smart - beautifully dressed and well made up considering it was the war years. The other observation is OH & S was almost non-existent in those days. I wonder if any of the workers succumbed to excessive x-radiation or toxic chemical exposure. I guess working conditions in the USA back then would be what occurs in third world countries like India and China today.

Good find, and quite educational.

[daqq]

OH & S was almost non-existent in those days.

See: https://en.wikipedia.org/wiki/Radium_Girls

(Preferably on an empty stomach)

The dangers of radiation were not always understood, radium and other things radioactive were used as a quack medicine.

[mikeselectricstuff]

" A zig-zag funnel-like contrivance" for shock testing - love it!

[timb]

Man, you think something as simple as a frequency crystal couldn't be that hard to manufacture... I had no idea there were that many steps from raw Quartz to to finished product! Also, changing the frequency with X-Rays was pretty cool too!

It was also striking (no pun intended) just how big the finished parts were! I mean, even the sliced sections of Quartz by themselves were large, especially considering the frequency (which was in the kHz range I imagine). Compare that to modern crystals; today a unit in a through hole package would be considered large compared to a two pad SMD crystal, and those cover up to 100MHz!

[fubar.gr]

My guess is that crystal size is inversely proportional with operating frequency.

Therefore a high frequency crystal will be tiny.

[timb]

My guess is that crystal size is inversely proportional with operating frequency.

Therefore a high frequency crystal will be tiny.

I believe it's the thickness of the crystal that determines frequency; the thinner the crystal the higher the frequency. In the old style crystals shown in the video, they would be be batch polished to a specific thickness, then etched together. Next, each individual slice was hand tested for frequency and then hand etched again if it was too thick/too low of a frequency. They'd repeat that process until the frequency was within tolerance.

The reason for this has to do with how the crystal works and the interior of it. If you notice in the video, the raw slabs of Quartz are optically measured for correct orientation multiple times during processing.

Think about it, 32.768kHz watch crystals are some of the smallest crystals you can get. That wouldn't be the case if size was inversely proportional to frequency.

[mikeselectricstuff]

My guess is that crystal size is inversely proportional with operating frequency.

Therefore a high frequency crystal will be tiny.

I believe it's the thickness of the crystal that determines frequency; the thinner the crystal the higher the frequency. In the old style crystals shown in the video, they would be be batch polished to a specific thickness, then etched together. Next, each individual slice was hand tested for frequency and then hand etched again if it was too thick/too low of a frequency. They'd repeat that process until the frequency was within tolerance.

The reason for this has to do with how the crystal works and the interior of it. If you notice in the video, the raw slabs of Quartz are optically measured for correct orientation multiple times during processing.

Think about it, 32.768kHz watch crystals are some of the smallest crystals you can get. That wouldn't be the case if size was inversely proportional to frequency.

watch crystals work on a different principle to normal ones - they use a tuning fork structure to get a low frequency in a small size.

[Halcyon]

Just when you think the crystal is just about finished, here come 10 more manufacturing steps. Wow! What a complicated process it was.

Thanks for posting, it was interesting. No gloves when using the rotary saws either with their hands getting awfully close. I could imagine the WH&S nazi's having a field day.

[Towger]

No gloves when using the rotary saws either with their hands getting awfully close. I could imagine the WH&S nazi's having a field day.

It would be a worthy collage project to track down the factory and interview the employees (or their families) just to find out what the long term health effects were.

[PA0PBZ]

Wow, I never realized that there where so many steps in manufacturing these crystals back then. I wonder what the cost was, a $100 crystal anyone? Thanks for posting this!

[timb]

My guess is that crystal size is inversely proportional with operating frequency.

Therefore a high frequency crystal will be tiny.

I believe it's the thickness of the crystal that determines frequency; the thinner the crystal the higher the frequency. In the old style crystals shown in the video, they would be be batch polished to a specific thickness, then etched together. Next, each individual slice was hand tested for frequency and then hand etched again if it was too thick/too low of a frequency. They'd repeat that process until the frequency was within tolerance.

The reason for this has to do with how the crystal works and the interior of it. If you notice in the video, the raw slabs of Quartz are optically measured for correct orientation multiple times during processing.

Think about it, 32.768kHz watch crystals are some of the smallest crystals you can get. That wouldn't be the case if size was inversely proportional to frequency.

watch crystals work on a different principle to normal ones - they use a tuning fork structure to get a low frequency in a small size.

Doh! I knew that... For some reason it just didn't occur to me while typing that sentence.

[radar_macgyver]

No gloves when using the rotary saws either with their hands getting awfully close. I could imagine the WH&S nazi's having a field day.

One generally does not wear gloves near rotating machinery. The gloves rarely protect you from injury, and can make matters worse by getting caught in the spinning machinery and pulling your hand in.