Voron TAP: Contact-Based Probing Deep Dive

Danielle A.

The Nozzle as Probe

Voron TAP is a toolhead design innovation for Voron 2.4 and Trident printers that fundamentally changes how Z probing works. Traditional ABL probes such as inductive sensors, capacitive sensors, and BLTouch measure the distance from the probe sensor to the bed surface, and the firmware uses a configured XY and Z offset to calculate where the nozzle actually is. This offset is temperature sensitive and calibration sensitive, introducing small but meaningful sources of error that affect first layer consistency.

TAP eliminates the Z offset entirely by making the nozzle itself the probe sensor. The toolhead carriage mounts on a small secondary carriage via an optical switch. When the nozzle contacts the bed, the toolhead carriage shifts slightly upward, triggering the optical switch. The measurement is taken at the actual nozzle tip, which is the exact same point that will be printing, so there is no XY or Z offset to manage. The probe point is identical to the print point, regardless of thermal expansion or calibration drift.

Benefits in Practice

The practical improvement from TAP is most evident when switching between materials that print at very different temperatures. With a standard inductive probe, the Z offset calibrated for PLA at 200°C will not be exactly right for ABS at 250°C. The hotend expands with heat, shifting the nozzle position relative to the probe offset. TAP measures at whatever temperature you are printing, so it naturally compensates for thermal expansion. Makers who switch frequently between materials report far more consistent first layers without needing to adjust Z offset between changes.

The probing force is also extremely gentle, just enough to trigger the optical switch. This is kinder to delicate build surfaces such as soft PEI coatings than a heavier probe that may interact inconsistently with textured surfaces.

Installation and Configuration

TAP is a printed replacement for the standard Voron toolhead MGN12 carriage on the 2.4 or the NEMA17 mount on the Trident. Print the TAP carriage and required components in ABS or ASA. The carriage sits near the hotend and must withstand elevated chamber temperatures that would soften PLA. Source the optical switch from the official BOM or the Voron sourcing guide, as component quality directly affects trigger consistency. Wire the switch to a spare endstop pin on your control board.

In Klipper, configure TAP using the standard probe block with the optical switch pin. Run PROBE_CALIBRATE to establish the initial Z offset, then verify with a test print. Full TAP build documentation is available in the official Voron GitHub repository. For best results, pair TAP with a well tuned mesh by following an advanced bed meshing guide to fully leverage its accuracy.