[time-nuts] AN/URQ13 reference AT cut crystal?

[Lux, Jim]

On 2/18/21 3:53 AM, Poul-Henning Kamp wrote:
> --------
> Bob kb8tq writes:
>
>> Turning an “idea” into a production capable part involves making many
>> batches of test samples. Think in the thousands of batches and hundreds
>> of parts in each batch. You have a “search” process at the blank chopping
>> level. You also have a search at the resonator fabrication level. Getting the
>> chopping part right is only a small part of the whole process….
> I realize this used to be a manual process, but today I would expect
> that you could automate a lot, of not most of it, if you wanted to ?


That was my first thought, and then I thought through all the steps. I 
think it would be challenging to automate (and that brings up your 
question below about "is it worth it?")

First, are you starting with natural or grown quartz? ( While grown 
quartz is used for most crystals, isn't there some performance benefit 
from natural crystals?)

I assume there is some sort of process to create "bars" of quartz from 
the raw boules or crystals.

I believe you'd need to do some analysis to determine the crystal axes 
and then the bars go into a series of saw steps - those might be 
automateable, in terms of sawing angles - is the sawing with a wire, 
with a diamond blade, or these days, perhaps abrasive water jet?  That 
would give you a bunch of slabs with the cut with the right angles - I'm 
sure the machine they use today probably dumps them in a hopper, and 
I've watched enough food packaging shows to know that you could get 
those fairly large slabs onto a conveyor.

Then you'd have to cut your desired crystal shapes out of the slab 
(whether round, rectangular, or some other shape) - another sawing or 
grinding step, I assume.

And then mount in a holder automatically.

All the individual steps are sort of "mass production" but I think 
today, there's significant (manual) setup time for the machine between 
steps (kind of like making tiny screws on a Swiss Screw Machine - some 
time for setup, then feed in bar stock and tiny screws or spacers come 
out of the machine)

https://www.youtube.com/watch?v=mhwUHgWzzKs




>
> It would still be a lot of work, and very expensive, but like
> biochemist trying out hundred of thousand compounds from their
> "libraries", robots really lower the cost.

Lot of work, I think, underestimates the magnitude of the task. It would 
be interesting to compare the processes used for creating high 
performance crystals (e.g. for a USO, where they start 1000 blanks to 
get a dozen or so oscillators) and those used for mass production of 
crystals for things like kitchen timers and microcontrollers.  I have 
heard that for USOs, there's a couple people who have the "knack" for 
installing the crystal in the holder in a way that minimizes the 
stresses, etc.   That is *really hard* to automate.

This is, of course, where SiLabs has a thing - they make hundreds (if 
not thousands) of MEMs oscillators at once with lithography, so the 
piece parts are very inexpensive - but they're performance limited by 
the material.


>
> The real question must therefore be, if anybody reasonably expects
> there to be any superior "new" cuts to find in the first place ?
>
> What properties would you program a quartz-crystal-prototyping robot to search for ?
>
> Which parameter(s) of current crystal-cuts are "their weak point" ?
>