HOW TO MAKE ALMOST ANYTHING - MACHINE WEEK
The gantry is a custom CoreXY mechanism mounted beneath the Ouija table. Its job is to move a magnet-carrying end effector in the X–Y plane so that the cursor above can be pulled smoothly across the board. Because the system is completely hidden inside the table volume, the motion feels disembodied to the user: the planchette moves “on its own,” while the CoreXY quietly routes belts, pulleys, and bearings under the surface.
Ryan led the CoreXY gantry design and assembly that would be situated under the Ouija table to maneuver the cursor piece above with hidden magnets. All the structural parts were custom designed, and a flexure detail embedded in the carriage allows for tightening the V-groove wheels against the extrusion. In consultation with Ilan, we designed a custom belt path to keep tension even and minimize racking. (To be continued / expanded by Carlos and Ryan.)
The size of the gantry is approximately 18" × 18". The main custom components (including 3D printed parts) are:
Together these parts form a kit-of-parts gantry that can be assembled, tensioned, and aligned under the table, and later integrated with the end effector and electronics.
All structural parts for the CoreXY system were modeled in CAD to fit within the 18" × 18" envelope and clear the underside of the table. The side carriages and corner blocks reference standard V-slot practices but are customized for our particular extrusion spacing and belt routing. The effector carriage interfaces directly with the end effector assembly, providing a rigid platform for the magnet and any future sensing hardware.
The gantry was first assembled as a standalone frame, then aligned and fixed to the underside of the table. Belt tensioning was done iteratively, using the flexure in the carriage to dial in wheel preload and eliminate wobble. Once the motion was smooth and repeatable, the end effector was bolted onto the carriage and the electronics team connected the stepper motors and limit switches.
Table integration focused on ensuring that the gantry could be accessed for maintenance while remaining invisible from the user’s point of view. Clearances were checked so that even at maximum travel, the effector and belts do not collide with the table structure.
The gantry stepper motors and limit switches connect to the control electronics, which handle homing, coordinated X–Y motion, and scripted paths. Motion profiles were tuned so that the planchette movement could shift between smooth gliding and sharp, unsettling jumps, matching the “haunted” narrative of the overall installation.