Thread by @giopagliari

Just some notes on "Cryogenic Nano-Actuator for JWST"

#jwst

PDF (2006):esmats.eu/amspapers/past… via @markmccaughrean

[Thread] 1/n

Location of actuators shown in the diagram

Actuators fixed to "Delta Frame". Mirror allowed to move relative to it. Actuators flex the mirror.

Diagram showing details of actuator:

* Athermalization Bracket - orange
* Actuators - blue
* Movable - grey - Interface to Mirror "Wiffle Bracket"

"Wiffle" is not in the scrabble dictionary

"Athermalize"

"to render (something, such as an optical system) independent of temperature or of thermal effects"

merriam-webster.com/dictionary/ath…

I'm guessing "Wiffle" in this context means "hollow plate" and seems to be a baseball reference.

Actuator requirements
* Position/Support
* Cryogenic conditions
* Long-life

2 inventions related to the actuators (by @BallAerospace):

* Flexture device
* Deadband coupling

This coupling might explain why there isn't constant movement of the actuators - as the deadband coupling needs to be engaged to use the fine tuning.

Need a coffee break lol

This diagram is clear, it shows:

* Motor - yellow

The motor moves the red unit directly with a gear and indirectly moves the green unit through a 90-degree bevel gear.

* Cam shaft - red

Moves the deadzone couple (green/blue interface) and the flexture (top of drawing)

It shows how the motor can turn the red shaft (and do the fine adjustments) without needing to move the blue shaft (unless required).

That's it. Some other interesting points:
* dry film lube is used for operation at 30K
* all motor revolutions are recorded - as it is limited to about 1.7 million rotations
* gears made from titanium
* tested in sub-component combinations
* 140 units were "mass-produced"

Thanks