Ultimaker Short Belt Tensioner

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The tightener can freely move along the belt. Flanges on roller parts securely hold the assembly in place, preventing it from falling off. If rattling or rasping noises occur, attach small pieces of felt to the faces touching the steppers or walls. Save the nuts and glue the guide bar screws into one slider part for efficient printing. Print at 0.1mm layer height, 1.2mm wall thickness, and 20% infill for optimal results. Clean bores after printing to allow sliders to move smoothly along guide bar screws. Tighten roller screws to a loose fit to enable ball bearings to move freely. Check the rollers and sliders for smooth operation before attaching tighteners to belts. Snap on belt tighteners onto short belts, ensuring flanges embrace the belts at the side facing walls. If the belt is too close to the wall, re-adjust pulleys to maintain 1-2mm clearance from walls. Rollers should barely touch walls without scratching them. Regarding concerns about adding a spring to the drive system, I agree that it may introduce negative effects on dynamical properties. However, these concerns do not apply here as the sprung system is not supported by the non-moving frame. Directional changes of belt movement will not cause the spring to be deflected or store/release energy. When one piece of the belt tightens, the opposite part loosens in the same way, causing the tensioner assembly to move laterally slightly. The spring applies "static" stress to both belt parts symmetrically without any dynamics in tensioner length. Fixing one part of the tensioner body to the frame would introduce ringing and overshooting on directional changes. Minor adjustments have been made to the roller part. Flanges have been extended to prevent the tensioner from occasionally falling off, and a larger bore has been added for an additional washer to reduce friction between the roller and screw.