We offer one of the largest variety of retention knobs in the United States. We offer USST, Lyndex and Parlec knobs in CAT and BT Tapers. If you cannot find the correct retention knob, please call us and let us help you locate the correct knob for your machine.

Why Choose USST Retention Knobs? 

• Quantity discounts are now available for end users : 10 pcs - 10% off; 15 pcs - 15% off.

• Each retention knob is certified free of cracks after being INDIVIDUALLY Magnetic Particle Tested by an Independent Nationally Certified Laboratory in the U.S. to ensure knob integrity. (ASTM E1444-01) 

• Manufacturing date, batch number and part number are all clearly laser marked on each retention knob. 

• Knobs are made to applicable standards (ANSI, JMTBA, DIN). 

• Coolant holes are left non-carburized. • Made from 8620, heat-treated to RC 56/58. 

• Stronger threads resulting from thread rolling on a vast majority of the knobs. 

• High quality black oxide treatment to ensure long life.

• Made in USA.

Is It Time To Replace Your Retention Knobs? If you cannot remember the last time you changed retention knobs, it may be time to replace them. Instead of sending your retention knobs out for expensive testing, you can replace them with high quality USST knobs for a fraction of the cost!

  SELECTION OF THE CORRECT KNOB

Machine tool manufacturers use various styles and sizes of retention knobs. They often look similar and appear to be interchangeable, but in reality they are not. It is very important not to interchange metric retention knobs with inch toolholders. The use of the incorrect knob, or the incorrect usage of a knob, may result in injury or property damage. To ensure choosing the correct knob, please use the following guidelines:

1) Specify the make model and spindle size of your machine. 2) Make sure that the "critical dimensions" are correct. The retention knob print, usually found in the machine manual, is one of the best tools for selection of the correct knob. 3) The part number of previously used retention knobs from any manufacturer can also help us provide you with the correct knob for your machine. Our database contains most manufacturer’s part numbers

We try to insure that we specify the correct knob, however, it is the responsibility of the end user to check that the supplied knobs are correct for the machine tool and taper type.

Machining Center manufacturers have increased the draw bar force on retention knobs frequently in recent years. It is now more important than ever to check your retention knobs periodically. Remember to fully tighten the retention knob. Failure to do so may result in the toolholder coming loose during operation.

A machine out of alignment or used beyond capacity can cause failure. Metal fatigue, over time, can also cause failure. Retention knobs should be inspected periodically and replaced. Any signs of wear or damage indicate that the retention knobs should be replaced. Every 2 to 3 years, depending on use, knobs should be removed from the holder and inspected. Any retention knobs showing indications of cracking must be discarded. If your machine has been in a collision, or releases a tool prematurely, this is may be an indication that the retention knob fingers, finger guide, belleville washers or the retention knob itself may be damaged. The machine tool should not be used until inspected by Maintenance or Factory trained personnel. In this case, all of the machine’s retention knobs should be checked for cracks or damage immediately.