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CAT Retention Knobs

  • All mating surfaces precision ground

  • Manufactured from aircraft quality AMS-6274 alloy steel

  • Hardened for maximum longevity

Product Description

CAT Retention Knobs are manufactured from aircraft quality AMS-6274 alloy steel and  are hardened for maximum longevity. Match the dimensions and appearance of your retention knob to the drawings below. Use the manufacturer’s print that came with your machine to verify your selection. For safe operation,  ensure the pull stud you order is the exact pull stud your machine uses. Using the wrong pull stud can cause damage to the spindle and/or toolholder, and can create a safety hazard.

ANSI Style
DIN 69871B
DIN 69871A
Part No. Type θ d1 d2 d3 l1 l2 T
21006-15 CAT40-DIN 15° .750" .550" .640" 1.024" .787" 5/8 - 11
21007-15 CAT40-DIN 15° .750" .550" - 1.028" .792" 5/8 - 11
21003 CAT40-ANSI 45° .740" .490" .490" .640" .440" 5/8 - 11
21003-45 CAT40-MAS-I 45° .590" .394" .512" 1.266" .990" 5/8 - 11
21003-60 CAT40-MAS-II 60° .590" .394" .512" 1.266" .990" 5/8 - 11
21003-90 CAT40-MAS-III 90° .590" .394" .512" 1.266" .990" 5/8 - 11
21005-45 CAT50-MAS-I 45° .906" .669" .827" 1.772" 1.378" 1 - 8
21005-60 CAT50-MAS-II 60° .906" .669" .827" 1.772" 1.378" 1 - 8
21005-90 CAT50-MAS-III 90° .906" .669" .827" 1.772" 1.378" 1 - 8
21008-15 CAT50-DIN 15° 1.101" .825" - 1.338" .984" 1 - 8
21005 CAT50-ANSI 45° 1.140" .820" .820" 1.000" .700" 1 - 8
17836 CAT40, ANSI, w/ metric thread 45˚ .740" .490" .490" .630" .56" M16
21006-15C CAT40-DIN Coolant 15° .750" .550" .640" 1.024" .787" 5/8 - 11
21007-15C CAT40-DIN Coolant 15° .750" .550" - 1.028" .792" 5/8 - 11
21148-C CAT40-Coolant Mori-Seiki 15° .747" .548" .641" 1.024" .787" 5/8 - 11
21003-C CAT40-ANSI-C 45° .740" .490" .490" .640" .440" 5/8 - 11
21003-45C CAT40-Coolant-I 45° .590" .394" .512" 1.266" .990" 5/8 - 11
21127-C CAT40 - Coolant Okuma 45° .740" .490" .490" .640" .440" 5/8 - 11
21003-60C CAT40-Coolant-II 60° .590" .394" .512" 1.266" .990" 5/8 - 11
21003-90C CAT40-Coolant-III 90° .590" .394" .512" 1.266" .990" 5/8 - 11
21003-45CSF CAT40-Coolant-I SlimFIT 45° .590" .394" .512" 1.266" .990" 5/8 - 11
21003-60CSF CAT40-Coolant-II SlimFIT 60° .590" .394" .512" 1.266" .990" 5/8 - 11
21003-90CSF CAT40-Coolant-III SlimFIT 90° .590" .394" .512" 1.266" .990" 5/8 - 11
21005-45C CAT50-Coolant-I 45° .906" .669" .827" 1.772" 1.378" 1 - 8
21005-60C CAT50-Coolant-II 60° .906" .669" .827" 1.772" 1.378" 1 - 8
21005-90C CAT50-Coolant-III 90° .906" .669" .827" 1.772" 1.378" 1 - 8
21008-15C CAT50-DIN Coolant 15° 1.101" .825" - 1.338" .984" 1 - 8
21005-C CAT50-ANSI-C 45° 1.140" .820" .820" 1.000" .700" 1 - 8

Rentention Knob Best Practices

Regularly inspect retention knobs for signs of wear. Wear may appear as dimples or grooves under the head or visible corrosion anywhere on the retention knob. If the retention knob demonstrates any signs of wear replace it immediately. 

Make sure to properly torque the retention knob to the manufacturer’s specifications. Use a torque wrench and retention knob adapter to ensure proper torque. Over-tightening can overly stress the retention knob leading to premature failure and can cause the tool holder taper to swell leading to a poor fit between the machine spindle and the tool holder.

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