$0.50R-25B Pneumatic Rotational Stepper Motor

myminifactory

The R-25B is a highly advanced pneumatic rotational stepper motor that packs a powerful punch in a compact package measuring only 25 mm. Its step size is an impressive 10°, and its output torque is remarkably high for its small size, reaching up to 0.1 Nm. The pressure range of the R-25B depends on material strength, typically falling within the range of 0.1-0.4 MPa (1-4 bar). Designed specifically for use in high-resolution Polyjet printers like the Stratasys Objet260, the R-25B is a precision-crafted motor that can also be used with FDM printers, especially those with small nozzle sizes. However, this has yet to be thoroughly tested. The top of the R-25B features a unique multi-material design consisting of a rigid body and a rubber component for sealing. Vero material is used for the rigid parts, while Agilus or Tango is employed for the rubber components. If you don't have access to a multi-material printer, simply printing everything in rigid material will suffice. The seals on the R-25B are crafted from 0.5 or 1 mm thick silicone rubber (Shore 60A) and can be laser-cut into custom shapes. The dimensions of these seals may require adjustment for optimal fit. To ensure smooth operation and prevent accidental gluing, apply petroleum jelly (such as Vaseline) to the axle, pistons, and seals. This lubricant also serves as a protective coating against accidental bonding. Once assembled, glue the top onto the housing using Loctite 406+770. A suggested method is to first assemble the parts and then apply glue along the slit before letting it dry completely. The tube sockets on the R-25B are 3 mm in diameter, and Festo offers matching tubes for purchase. Alternatively, I have a housing available for use with 2 mm tubes - feel free to contact me for more information. Interestingly, the original R-25 motor was described in a paper that detailed an earlier version of the design featuring 13 teeth instead of the current 9, and a step size of 6.9° rather than 10°. The original design's teeth shape proved too weak under high stress, leading to the development of the more robust R-25B model.