Mellow Hartk Sexbolt — Z Endstop for Voron 2.4 and Trident

The Mellow Hartk Sexbolt is a Z-endstop assembly for Voron 2.4 and Trident printers that use a fixed nozzle-actuated pin to establish their height reference. It combines the moulded housing, microswitch PCB and pin guide in a compact unit, avoiding the need to source and assemble the housing and endstop mechanism separately.

A Z reference through nozzle contact

During Z homing, the nozzle presses the pin, which transfers the movement to the microswitch. The firmware uses the resulting change of state as a reference. As contact is made with the nozzle itself, the trigger point depends on its actual position. Check and recalibrate the Z reference after changing the nozzle or modifying the hotend.

This assembly does not measure the bed surface or create a levelling mesh. It may work alongside a separate probe used for other operations, but it does not automatically replace an inductive probe, Klicky, TAP or another probing system.

Construction of this Mellow version

• Glass-fibre-reinforced nylon moulded housing: supplied as part of the assembly; no need to print this housing.
• Graphite copper sleeve: provides a dedicated sliding guide for the pin instead of using a modified pulley as its support.
• 5 × 30 mm metal pin: transfers nozzle pressure to the switch.
• PCB-mounted microswitch with a two-pin connection: provides an XH2.54 connection for endstop wiring.

The Sexbolt name comes from Hartk's modification. This commercial version has its own housing and guide, so it does not require reproducing the printed parts, sleeves and screws from the original assembly.

Technical specifications

Mounting and connection

1. Check that the location and mounting suit your Voron revision and that the nozzle can reach the pin without touching the bed edge or other components.
2. With the printer powered off, prepare the wiring to a mechanical-endstop input on the controller. Identify signal and GND in the board documentation: this two-pin connector is not a 12 or 24 V power input.
3. Before moving the printer, gently press the pin and check that the switch changes state and the mechanism returns freely without sticking.
4. Verify the firmware state and homing coordinates before running an automatic movement. Keep the nozzle tip clean, as plastic residue can affect contact.

Checking in Klipper

Configure the appropriate input in endstop_pin under [stepper_z]. The pin depends on the board. Pull-up (^) and logical inversion (!) must match the wiring and input, rather than being copied based on the accessory name.

QUERY_ENDSTOPS

The endstop should report open at rest and TRIGGERED when the pin is pressed. If it does not change or reads backwards, correct the connection or configuration before homing.

Once motion and homing have been checked, use Z_ENDSTOP_CALIBRATE to calibrate the reference relative to the bed. Complete the procedure with ACCEPT and SAVE_CONFIG. These commands do not replace checking the XY homing position or configuring the machine correctly.

Checking in Marlin

Select the Z input required by your installation and use M119 to check its state, first at rest and then while pressing the pin. Set the endstop logic in the configuration for your Marlin version before testing movement.

For you if

You are building or maintaining a Voron 2.4 or Trident with a fixed nozzle-actuated Z endstop and want a combined moulded housing, guide and microswitch assembly.

Not for you if

You need a bed-mesh probe, an endstop for any printer without adapting the mounting, or your printer already homes Z through another system and does not need this mechanism.

Included

One assembly with black housing, microswitch PCB, guide sleeve with 5 mm internal diameter, 5 × 30 mm pin and two-pin connection terminal. You will need wiring and mounting hardware suitable for your printer.

Resources and related products

See Hartk's original project for the origin of the design. Its files and bill of materials apply to the original mod, not the contents of this Mellow kit.

For your project structure, we offer configurable printed-parts kits for Voron 2.4 R2 and Voron Trident r1. Check each kit's revision and mounting options before combining them.