The complete file

Every entry

All twenty-nine, grouped by section, in reading order. This is the dense view; the front page is the edit.

Entry	Section	What it turns on
Repeatability is not accuracy	Repeatability	An arm quoted at ±0.03 mm will return to the same wrong place all day. Repeatability is agreement with itself; accuracy is agreement with the world, and almost every published figure is the first one.
What the figure excludes	Repeatability	Quoted cold, unloaded, at rated speed. Three conditions no production cell meets.
Thermal growth	Repeatability	Steel grows as the cell warms. The first hour of a shift is not the fourth.
Payload and droop	Repeatability	Mass at the wrist bends the arm. The number falls as the load rises.
Calibration	Repeatability	Measuring the arm against a known artefact to turn repeatability into accuracy.
Why six	Six Axes	Three to place a point anywhere in reach, three more to arrive at any angle. Fewer and orientation is constrained; more and the solution stops being unique.
The shoulder carries	Six Axes	The first three joints do the lifting; everything outboard is about attitude.
The wrist	Six Axes	Three axes crossing near a point, and the compactness that makes it possible.
Gear and backlash	Six Axes	Where lost motion enters, and why the reduction ratio is so extreme.
Brakes	Six Axes	What holds the arm up when the power goes off.
Teaching a path	The Pendant	A programmer drives the arm to a pose and stores it. The program is a list of places, not a description of a motion.
Joint move or linear move	The Pendant	Two ways between the same two points, and only one of them is a straight line.
Blending	The Pendant	Rounding the corner between two moves to keep the speed up.
Frames and offsets	The Pendant	Describing a position relative to a fixture, so moving the fixture moves the program.
Dry run	The Pendant	The same path at a fraction of speed, which is the only sane way to see it first.
Holding what you cannot feel	The Hand	A two-finger gripper has no idea what it is holding. Everything is inferred from position, pressure and whether the part arrived.
Vacuum against fingers	The Hand	Suction is fast and forgiving on flat clean surfaces, and useless otherwise.
Compliance	The Hand	Deliberate springiness so a slightly misaligned part still seats.
Tool centre point	The Hand	The arm moves a point you define. Define it wrong and every move is wrong.
Quick change	The Hand	Swapping the hand mid-cycle, and the repeatability that costs.
Where the maths runs out	Singularity	In certain poses two axes line up and the arm loses a degree of freedom; the controller demands infinite speed to continue and stops instead.
Wrist flip	Singularity	The alarming fast rotation as an arm passes near a singular pose.
Planning around it	Singularity	Choosing an approach that never puts the wrist in line with the shoulder.
Reach is not a sphere	Singularity	The working envelope has holes in it, including one right in front.
The fence is part of the machine	The Cell	The guarding is not an accessory bolted on afterwards; the cell is designed as one system and the arm's speed and reach are set by it.
Light curtains and scanners	The Cell	Two ways of noticing that something has entered, with different response times.
Reduced speed	The Cell	The mode that exists so a person can be present at all.
The floor plate	The Cell	Anchoring, levelling and why the bolts matter as much as the arm.
What a cycle time hides	The Cell	Quoted for the move, not the waiting, the indexing or the part that did not arrive.