01 · The problem
Hold a satellite without touching it
Only a CubeSat’s four corner rails are allowed to touch the launch deployer. Every other face carries solar cells, connectors or switches. Most labs rest them on foam or hold them by hand.
- 1U to 3U, up to 340.5 mm long and 6 kg
- Touches only the rails, through POM plastic pads
- Single-axis jigs can’t reach the ends, where the deployment switches usually are
02 · Yaw axis
The whole top turns on one shaft
A Ø300 mm yaw plate spins on a stainless steel shaft over a plastic thrust washer. An M12 stud and a retainer washer stop it from lifting off.
- Ø400 × 12 mm aluminum base on four rubber feet
- Twelve holes in the base: a Ø6 pin locks it every 30°
03 · Pitch axis
The cradle flips end over end
Two 15 × 50 × 280 mm uprights carry the pitch shafts 220 mm above the plate. I put the satellite’s center exactly where the two axes cross. Its weight stays centered at any angle, so the cradle doesn’t swing when you pull the pin.
- Indexing disk: 360° in 30° steps, same as yaw
- About 70 N of sideways push to tip it with 6 kg loaded
04 · The cradle
Sized by calculation, not by guess
I checked the hub plates in bending, assuming the worst case:
σ = M / S = (41 N × 67.5 mm) / (50 × 8² / 6)
σ ≈ 5.2 MPa vs. 276 MPa yield (6061-T6)
safety factor ≈ 53
That told me my first 130 × 150 mm plate was far bigger than it needed to be. I cut it down to a 50 mm strap, which saved 0.52 kg and blocks far less of the satellite.
- Stop brackets pin into three spots, for 1U, 2U and 3U. One iLogic rule in Inventor moves all eight.
05 · Built to be built
41 parts, about $600 of metal
Plates in 6061-T6 aluminum for a waterjet or mill. Shafts and pins in 304 stainless for the lathe. Commercial jigs that turn on only one axis start around $7,500.
- Grounded to the ESD bench, with a lanyard on every pin
- Next: the upright bolt pattern and FEA, then machining it myself on the Tormach