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Standard retention knob, CAT 50, 1"-8, 90°, Coolant through

Retention Knob Information and Installation (PDF)

Retention Knob Installation Video

Category: Retention Knobs
Thread Size: 1.00-8
Angle: 90
Knob Diameter: 0.903
L1 Length: 1.3840
L2 Length: 1.778
Flange Thickness: 0.392
Hole Diameter: 0.250
Neck Diameter: 0.668
Pilot Diameter: 1.026
Shoulder Diameter: 1.438
Wrench Flat Diameter: 1.245
Socket Part #: RKW50
Number: JM34218B
Alternate Part: JM34218BHT, JM34218BHTHS
Country of Origin: USA

This knob is a replacement for the following parts:

ManufacturerPart Number
Retention Knob Supply: RK342-18B
Seco: 1694
Techniks: 21005-90C
Kenn 2: 2878475
Command: RB6E-0003-C
Davies: PSC-536X90
Kennametal: RK342-18B
Lyndex: C50-9000H
MSC: 1401975
Parlec: 5001TRKC
For Machines (see disclaimer)*: Mori Seiki, Okk

* Retention knobs are not interchangeable. Machines are only given as a reference, JMPP makes no guarantee this is the correct knob for your machine. Please call us at 1-800-322-7750 or email for knob identification help.

WARNING: The steel alloy used in this product contains chromium and nickel. This product can expose you to chemicals including chromium and nickel, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to