Register accuracy on a used offset press lives in two places: the cylinder gears and the sheet-transfer mechanism. On a Heidelberg 102-series, every sheet is gripped by the swing transfer after front-lay and side-lay registration, handed to the intake cylinder, then passed on to the impression cylinder. One mis-timed handoff is enough to show up as fan-out or poor back-to-back register. The tolerance allows no more than 0.01 mm height difference across the 19 gripper pads on the intake cylinder — far below what the eye can catch — which makes this mechanism a reliable tell of true machine condition.
- Pad height: referenced to the impression cylinder surface, nominal -0.1 mm with a -0.02 mm tolerance, measured at drive side, center and operator side
- Close angle: 26° on CD/CX102 and 48° on SM/SX102, with a window of just -0.3°
- Gripper preload: 27 ±0.2 mm spacing on hook-tooth cylinders; on straight-tooth versions the set screw sits 0.5–0.8 mm off its seat when closed, with 360 N springs
- Cam followers: grease starvation cracks and jams them — the most common root of transfer misfeeds; inspect every one
Timing is the first wear signal
All 19 grippers must close in the same instant. Jog the press to the closing angle, take the third gripper on the operator side as the reference, slide a 0.03 mm feeler gauge under it — slight drag on withdrawal is correct — then work through the rest, re-checking the reference every three teeth. If every tooth drifts the same way, the close cam has shifted and needs re-timing, not per-tooth fixes.
Pad height decides whether sheets wander
Worn pads sit below datum, loading the sheet unevenly at handoff: mild creasing at the grip edge at best, diagonal misregister at worst. Zero a dial indicator on the highest point of the impression cylinder with 0.3 mm preload, then level the pads across a 1000 mm straight edge to within 0.01 mm. Without instruments, look for polished bright patches — the shiniest pad has lost the most height.
A three-step field check
First, jog the press and listen: dry scraping at the cam followers, sludged grease or rust on the cam are all lubrication alarms. Second, print a solid flat tint and compare the grip edge color to color; re-measure with a 0.1 mm long feeler and a lay gauge if in doubt. Third, watch the transfer at low speed — a brief hesitation as a sheet meets the intake cylinder means timing has drifted, and that wear is worth pricing into your offer.
Bottom line: 0.01 mm pad leveling, a 0.3° closing window and a 0.03 mm feeler gauge turn transfer accuracy from a feeling into numbers — and wherever the numbers fail is exactly where your negotiating room begins.
