Hob Arbors Hob arbors, sometimes called hobbing fixtures, hold hob cutters while they cut the gear tooth profile. #CONCENTRIC specialty in tight tolerance #grinding allows us to create a tight clearance fit with minimal runout. Our #CONCENTRIC custom #hob #arbors can be designed to fit your hob machine through either, a pilot diameter, a cat taper, or an HSK connection with Hydraulic Lock Nut M30 x 1.5LH. Hob Mandrel With Hydraulic Lock Nut for Hobbing Liebherr machine. Rotary Engineering Corporation CONCENTRIC CUSTOMISED HYDRAULIC JELLY FILLING WORK HOLDING & TOOLING MANUFACTURER Global leading manufacturer of high precision hydraulic Jelly field clamping equipment & Tooling and work holding under the CONCENTRIC Brand.