BestEquip HGR20-600mm Linear Guide Rail Kit with RM1605-800mm Ballscrew & BF12/BK12 Supports - 2PCS Linear Slide Rails for CNC Routers, Lathes, Milling Machines - Perfect for DIY CNC Projects, Woodworking, Metalworking and Industrial Automation

I ordered these components for a CNC router I am making. I first purchased one to see if it was of acceptable quality, then purchased two more for dual Y axis and single X axis. The packaging was excellent, each piece sealed in a plastic bag and protected from shipping damage. All the parts were there and the fit and finish outstanding. I don't have the equipment to evaluate the tolerances down to the micron level but all the holes lined up and the parts slide as one would expect.The carriages do not move on the rails without some force, primarily due to the rubber wiper on each end of the carriage to protect the ball bearings. With 4X rails and 2X carriages/rail in the Y direction, this means there is a bit of force required to move the entire assembly. I am sure the NEMA 23 stepper motors will easily overcome this force through turning the ball screw but I was surprised at the friction of the seals. That said, the assembly is so rigid that my router seems like it will have incredible precision. We will soon see!