KP-55 Connecting Bolt 520K04

The KUPA Connecting Bolt #520K04 is a precision-machined metal bolt designed for the front-end assembly of the KUPA KP‐series handpieces (specifically the KP-55). It serves as a critical structural component, securing internal assemblies (such as rotors, spindles or housings) to ensure alignment, stability and high-speed performance. With wear or damage to this bolt, the handpiece might exhibit looseness, increased vibration or mis-alignment. This bolt matches OEM specs and is intended to restore proper fit and function. Features OEM Fit: Direct replacement for KUPA KP-55 handpieces, part number 520K04.  Dimensions: Outside Diameter (O.D.): approx. 19.91 mm (0.75″)  Inside Diameter (I.D.): approx. 11.56 mm (0.45″)  Length: approx. 29.47 mm (1.16″)  Material: High-speed compatible metal, designed for the rotational demands of nail-drill handpieces. Installation Tips Verify your current bolt’s dimensions and part number match 520K04 (O.D. ~19.91 mm, I.D. ~11.56 mm, length ~29.47 mm). Ensure that the handpiece you are servicing is indeed a KP-55 (or variant that uses 520K04) — other series may use different bolts. Power off and unplug the handpiece before disassembly. Remove the front housing and other relevant components to access the old bolt. Clean the bolt thread and housing area of debris, lubricant residue or metal shavings. Thread the new 520K04 bolt in carefully, ensuring proper torque (do not over-tighten, which could damage threads or housing). Re-assemble the handpiece, then perform a no-load test run to confirm smooth rotation, no abnormal vibration and secure assembly.