Skill Tree · T0 Instrument Control 3 exercises + Error Analysis
Correct execution Error — what wrong looks like Annotation — intended path
Step 1
Instrument control — a straight line laid down in one confident, committed pass.
Target the motor skill of driving a line from the shoulder/elbow and committing to it in a single stroke, not building it from short corrective marks. This is the untrained channel: CAD gave you 3D reasoning but never made your hand draw a line — and it is the bottleneck under every tier above. Step 1 also installs the anti-CAD-brain habits before construction begins: commit, don't correct; no ruler; no eraser. Method lineage: Drawabox Lesson 1 (superimposed lines → ghosted lines → ghosted planes), the ghosting method.
Exercise A · Sessions 1 — warm-up every session thereafter
Superimposed lines
Setup — pen (Micron 03), unruled white paper, ~10 min. Mark a start dot; pick a far endpoint by eye. No ruler, no eraser.
Procedure — anchor at the start dot and draw the same straight line 5–7 times, each a single full-speed pass, all sharing the one start point. Motion from the shoulder/elbow, never the wrist. Fill a page in varied directions. Mode: motor/mechanical.
Watch & measure — the far end. A tight bundle means the stroke is repeatable and committed; a fan means you are decelerating and steering.
Correct Far ends stay a tight bundle — the stroke is the same each time.WrongFanning & wobble = decelerating and steering mid-stroke. Ghost the motion, then commit full-speed.
Exercise B · Sessions 1–2 — the core rep
Ghosted lines
Setup — pen, unruled white paper, ~15 min. Mark two dots a hand-span apart at varied angles across the page.
Procedure — for each pair: (1) ghost the stroke — swing the pen above the paper along the intended path 3–4 times to program the motion; (2) commit one confident pass, pen down, full speed, eye locked on the end dot, not the pen. One line per pair — do not retrace, do not correct. Mode: motor/mechanical.
Watch & measure — does the committed line arrive at the end dot in a single smooth pass? A line built from short segments (stitching) or re-traced is a fail even if it looks straight.
Correct Smooth single stroke that lands on both marks. A slight bow is fine — commitment beats ruled precision here.WrongWobble + short segments = wrist-driven and correcting; the line stalls short of the mark. Drive from the shoulder; ghost, then one committed pass.
Exercise C · Sessions 3–4 — applying the stroke
Ghosted planes
Setup — pen, unruled white paper, ~15 min. Freehand a loose four-sided plane (irregular quadrilateral), corners marked as dots.
Procedure — connect the corners with ghosted, committed lines: the four edges, then the two diagonals — each a single pass, corner to corner, eye on the target corner. This forces committed strokes between fixed points at every angle. Mode: motor/mechanical.
Watch & measure — do the diagonals run straight, corner to corner, in one stroke? A bowed diagonal that misses its corner is the tell.
Correct Edges and diagonals run straight, each landing on its corner.WrongDiagonal bows and stops short of the corner — wrist pivot, no ghosting. Ghost the full diagonal first; keep the eye on the far corner.
Error analysis
End-of-session checklist
Line frays into several tracks / diagonals miss the corner→not ghosting enough, or decelerating near the end. Program the motion above the paper, then one full-speed pass.
Line is stitched from short strokes or re-traced→CAD-brain — correcting toward precision. Commit once; a confident bowed line beats a stitched straight one.
Line bows consistently the same way→drawing around the natural arc of a locked wrist/elbow. Rotate the paper so the stroke runs along your arm's arc, or open the joint.
Line misses the end mark→eye tracking the pen tip. Lock the eye on the destination dot before and during the stroke.
Reaching for a ruler, or wanting to erase→CAD-brain — precision instinct firing early. Banned by design at this stage; the wobble is the data that tells you what to fix.
Pass / adjust
Advance or repeat
Advance when both hold
1. Ghosted lines land on the end mark within roughly a pen-width on most attempts, each drawn as one committed pass.
2. No visible mid-line correction or stitching — lines read as smooth even if slightly bowed.
Repeat if lines are still stitched or re-traced, or you are relying on a slow wrist-driven stroke to stay accurate. That means the target — motor commitment — is absent. Straightness comes later; commitment comes first. Do not advance on time logged.
Date a filled page of ghosted lines and keep it in the bound sketchbook — it is your week-0 baseline for comparison. Superimposed lines (Exercise A) become the 5-minute warm-up at the start of every future session. Session shape: ~3 hr/week across 3–4 sittings; short and frequent beats long. Next node once this passes: T0 ellipses & line-weight control, then the T1 perception track.