Research note / Cycle 018
A path around the clamp
A sacrificial mock-up reaches the marked target positions but visibly flexes; clearance does not establish calibrated coverage.
Make a place for the target
The Space Elevator Initiative needs to observe the strip endpoints while the clamp occupies the direct line. Following Two targets around the clamp, Reed and Voss make SE-M18 from workshop card and thin plywood offcuts on January 25. These expendable pieces reproduce the proposed reach; they are not reference brackets.
On January 26 the straight approach fouls the occupied clamp. Both offset approaches reach the marked center and end positions in each travel direction without moving KIS-61 or KB-2. The mock-up is removed afterwards; NQ-17 remains returned.
A path that bends
Light finger pressure produces visible flex. No force or gap is measured. A reachable line is therefore established only for this mock-up at these positions. Neither support rigidity nor full-grid metrological coverage follows.
A separate constructed control gives both target readings a common 4 um shift: their difference is zero while their average remains wrong by 4 um. Agreement between targets cannot detect this common motion.
The next piece must carry a load of its own
The Abbé-error handbook discussion remains useful for identifying the offset between a reference and its point of interest. It supplies no stiffness or calibration for SE-M18.
The next decision is a rigid candidate with a documented support path and quantitative displacement checks. Strip loading and acceptance remain withheld. The 25 um budget, separate 6 um return allowance and 1000 um bidirectional grid remain unchanged.
Results at a glance
| Mock-up approach/control | Recorded observation | Scope |
|---|---|---|
| straight approach | fouls occupied clamp | not usable |
| offset approach A | passes at marked center and end positions in both travel directions | clearance only |
| offset approach B | passes at marked center and end positions in both travel directions | clearance only |
| light finger pressure | visible flex of mock-up | rigidity not established |
External research and methods
- Abbé Error · Dover Motion · Motion Control Handbook, Abbé Error section (Undated online handbook; retrieved 2026-10-26). Offset-arm/encoder example and angular-error discussion.