ToM APB Belt Tensioner

thingiverse

The primary objective of this device, known as the ToM APB (Automated Build Platform) tensioner, is to stretch the belt under high tension, emulating a solid surface like an HBP while retaining the ejection capabilities of the APB. It consists of a lever arm that attaches to the roller bar's sides and uses bearings for minimal friction contact. The tension can be adjusted by manipulating a screw located on the lever arm. This modification requires only two bearings and two short M3 screws, making it compatible with the stock APB. To ensure proper length of screws, countersunk head 10-15mm M3 screws are recommended for tension-setting purposes to avoid collision with Z-stage bars during homing and printing. A sturdy belt, like Tunell's Steel Conveyor Belt for ABP, is suggested for high tension use. After printing and cleaning up the parts, assembly involves placing bearings into the lever arm, partially screwing in the M3 nut, and attaching the backing bars to the X-axis endstop. The APB is then reattached to the ToM platform, with the lever arm pivot point bolted on the roller bar. Tensioning the belt requires finger-tightening each tension screw until it can no longer be tightened further and equal tightening of both sides. Proper tension is achieved when a fingernail cannot fit between the belt and heating board, and motor operation confirms that the belt doesn't obstruct movement. Lastly, check for normal end-axis functioning, clearance under the screw before the end-axis, and no collision with Z-stage bars to ensure optimal performance. The ToM APB tensioner aims to improve ABP functionality by providing high tension, flat surface emulation, and ease of ejection, encouraging users to promote the benefits of the ABP.