C. R. Onsrud Twin Table
Ballscrew Guys were called in to address the bridge Axis ball screw on a C. R. Onscrud Twin Table 194E18DH2 CNC Router. This machine is pretty neat. Twin table with twin heads, each head has its own ball nut. In this image you can see the top protective cover has been pulled back. You can see the Bosch Rexroth type ball screw assembly that connects the two machine heads. Ballscrew Guys have extensive CNC router experience. We fabricate our own aftermarket Rexroth improvement parts and seals.
The bridge Axis cover pulled back on an Onsrud twin table CNC router. Here you can see the drive pulley and servo motor that drives one of the two machine heads on this machine. Notice the buildup of sawdust and debris on the ball screw shaft. Over time and operation hours, that dust migrates into the ball nut. In time it will clog and block lubrication to the internal components. If not cleaned out and addressed, eventually the entire motion system will seize. It happens. This is why we have the images to prove it.
Better view of the Bosch Rexroth ball screw assembly moving the machine head. This is the bridge Axis on an Onscrud Twin Table 194E18DH2. On this machine, there are twin heads, each with its own dedicated ball nut and rotation bearing system. Both are pulley driven with a fixed ball nut shaft. The main issue with using these INA rotation bearings with Bosch Rexroth ball nut systems is that the lubrication delivery system is not enough for the application. CNC routers and woodshops are dusty. This gets into the ball nut. Some CNC routers, which use the same brand of components, like KOMO, put on their own designs of additional lubrication systems to the ball nut assembly.
The German-made Bosch Rexroth ball nut found on a ball screw assembly within an Onscrud Twin Table Router. This model used two of these ball nuts mounted on the bridge ball screw shaft. R253360021 65609.002 Ballscrew Guys make aftermarket refurbishment parts and seals for these ball screws. The Rexroth ball screw shaft design is one with four parallel raceways, wrapped around the shaft as a helix. The ball nut only rides on one of these raceways. So if you experience damage or failure, it is often possible to rebuild your ball nut and install it on an undamaged track.
Our aftermarket machined brass ball bearing recirculation guide insert is installed into a Bosch Rexroth R253360021 65609.002 ball nut. The original OEM ball screw ball bearing guides are made from plastic. This ball nut was from an Onscrud Twin Table. One of two ball nuts found mounted on the fixed position bridge ball screw.