§ 1The Only Sane First Look
When a path is taught on the pendant, the stored positions are a list of poses the arm will chase at full production speed the moment you tell it to run. Full speed, in this context, means whatever the program specifies — and on a six-axis arm that can be several metres per second at the tool tip. Sending an untested program at that velocity into a cell containing fixtures, cables, and everything else that was installed since the last dry run is not a test. It is a gamble.
A dry run is the same program executed at a fraction of rated speed — typically ten to twenty-five percent — so a person watching can follow the path as it unfolds. Nothing in the program changes. The interpolation, the blending between moves, the approach angles, the retracts: all of it runs exactly as written. Only the velocity scale drops. What the dry run exposes is whether what the programmer intended and what the program actually contains are the same thing.
They often are not. A joint-mode move that looks fine on paper can swing the elbow outboard in a way nobody anticipated. A retract that clears the fixture at one approach angle clips it at another. The tool-centre-point offset, if entered incorrectly, shifts every single move in the program by the same quiet error — invisible in simulation, obvious the moment the arm moves toward something solid. At slow speed, a watching operator can stop the run before contact. At full speed, there is no such margin.
Speed override is the mechanism: a percentage set at the pendant that scales the velocity of every motion in the program without altering positions or logic. Lowering it does not make the path safer in a geometric sense — the arm will still reach every stored pose — but it converts an event that would happen faster than a person can react into one they can actually observe. That distinction is the entire point.
A dry run is not a simulation and not a rehearsal. It is the program, running live, in the real cell, against the real fixtures, with the real tool fitted — just slowly enough that the result of the first run is data rather than damage.
At slow speed, a watching operator can stop the run before contact.
