A fascicle bundles multiple fiber pairs inside a 4mm PET braided sleeve with Kevlar strain limiters. Mirrors biological muscle fascicles exactly — fiber bundles wrapped in connective tissue (perimysium).
// FASCICLE CROSS-SECTION — 4mm PET SLEEVE
ASSEMBLY STEPS
1
Make fiber pairs (2-ply)
Take two identical finished fibers. Twist them together in the opposite direction to their individual coils. A few turns — enough to interlock. Fix both ends. They now contract in balance with no return spring needed.
2
Bundle 2–3 pairs
Group pairs in parallel. Fine fascicle: 2 fine pairs. Coarse fascicle: 2–3 coarse pairs. Keep nichrome wire ends accessible on both sides.
3
Add Kevlar strands between pairs
Run 2–4 Kevlar strands parallel alongside — never twisted in. These are strain limiters: they prevent over-contraction and fiber snap. Think of them as a leash, not a fighter.
4
Slide on 4mm PET braided sleeve
Over the full bundle. Housing + protection. Fill with light mineral oil or silicone oil for thermal management and faster cooling.
5
Twist all same-end nichrome wires together
Before connecting to MOSFET driver. One connection point per fascicle end = clean wiring.
💧 Oil filling: mineral oil or silicone oil both work. Light grade. Fill from one end using a syringe before sealing sleeve ends. Passive cooling — active micro-circulation is a future upgrade.
TWO FASCICLE TIERS
COARSE FASCICLE
Role: Movement + load bearing Recruited: On demand, burst PWM Control: High duty cycle pulses Fiber size: 0.1mm nylon / AWG34