{"product_id":"accupro-88-611-40-ap-cat40-retention-knob-5-8-11-thread","title":"Accupro 88.611.40.AP CAT40 Retention Knob 5\/8-11 Thread","description":"\u003ch3\u003eProduct Description\u003c\/h3\u003e\n\u003cp\u003eThe ACCUPRO 88.611.40.AP is a CAT40 retention knob designed to secure toolholders in CNC machining center spindles. It threads into the drawbar mechanism and holds the toolholder firmly during cutting operations. The 5\/8-11 thread size is standard for CAT40 toolholding systems. With a high-torque Style C configuration, this knob is suited for demanding milling applications where secure toolholder engagement is critical. The overall length is 2.248 inches, the knob diameter is 0.5905 inches, and the neck diameter is 0.3937 inches. Installation is performed by CNC machinists and toolroom technicians during toolholder setup or replacement.\u003c\/p\u003e\n\u003cp\u003eThis retention knob is used in CAT40 spindle toolholding systems found in vertical and horizontal machining centers across job shops, production facilities, and toolroom environments. The 45-degree angle radius seat and Style C profile are common in general-purpose and high-torque milling setups. No through-coolant capability is provided, making this knob appropriate for dry or flood-coolant applications where internal coolant delivery through the retention knob is not required.\u003c\/p\u003e\n\u003ch4\u003eKey Features\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003eCAT40 taper size for standard machining center spindle compatibility\u003c\/li\u003e\n  \u003cli\u003e5\/8-11 thread engages directly with the spindle drawbar\u003c\/li\u003e\n  \u003cli\u003eHigh-torque Style C design for secure toolholder retention under heavy cutting loads\u003c\/li\u003e\n  \u003cli\u003e45-degree angle radius seat for consistent seating and repeatable toolholder positioning\u003c\/li\u003e\n  \u003cli\u003eCompact neck diameter of 0.3937 inches reduces interference during toolholder changes\u003c\/li\u003e\n  \u003cli\u003eNo through-coolant — simplifies installation in standard flood-coolant or dry-cut setups\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eCompatibility\u003c\/h4\u003e\n\u003cp\u003eDesigned as an OEM-style replacement retention knob for CAT40 toolholding systems using a 5\/8-11 drawbar thread on standard CNC machining centers.\u003c\/p\u003e\n\u003ch4\u003eInstallation Notes\u003c\/h4\u003e\n\u003cp\u003eRetention knobs are installed by CNC machinists or toolroom technicians using a retention knob wrench and toolholder fixture to prevent rotation during torquing. Power down and lock out the machine spindle before servicing any toolholder or retention knob. Do not overtighten — follow the toolholder manufacturer's torque specification for the CAT40 interface. Inspect the knob threads and the drawbar threads for wear or damage before installation.\u003c\/p\u003e\n\u003ch4\u003eTechnical Specifications\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTaper Size\u003c\/strong\u003e: CAT40\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThread Size\u003c\/strong\u003e: 5\/8-11\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eStyle\u003c\/strong\u003e: C\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHigh Torque\u003c\/strong\u003e: Yes\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAngle Radius\u003c\/strong\u003e: 45 degrees\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eOverall Length\u003c\/strong\u003e: 2.248 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eKnob Diameter\u003c\/strong\u003e: 0.5905 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eNeck Diameter\u003c\/strong\u003e: 0.3937 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eKnob to Flange Length\u003c\/strong\u003e: 1.2637 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFlange Thickness\u003c\/strong\u003e: 0.9882 inches\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eThrough Coolant\u003c\/strong\u003e: No\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWeight\u003c\/strong\u003e: 0.25 pounds\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePackage Quantity\u003c\/strong\u003e: 1\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eStandard Information\u003c\/h4\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBrand\u003c\/strong\u003e: ACCUPRO\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer Part Number\u003c\/strong\u003e: 88.611.40.AP\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"ACCUPRO","offers":[{"title":"Default Title","offer_id":51747443048754,"sku":"88.611.40.AP","price":41.97,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0270\/4519\/9983\/files\/8574a9811b7cb6addc48503c8623693f.jpg?v=1788880323","url":"https:\/\/voomisupply.com\/products\/accupro-88-611-40-ap-cat40-retention-knob-5-8-11-thread","provider":"Voomi Supply","version":"1.0","type":"link"}