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Benefits and Warnings

Benefits to using Toolinghouse Retention Knobs:
Click here to view our Retention Knob and Pull Stud Offering.

Better Finishes
than are required by International Standards, reduces the likelihood of cracking.

Written Inspection Reports are kept on every work order/lot number manufactured.  This means that the same inspection criteria are used as if the parts were for aircraft.

Parts are Black Oxide to prevent rust.

Extra Labels with peel off backing are supplied upon request.  Many manufacturers have machines which use different retention knobs.  These labels are used to identify the type of retention knob used on the machine.  You can stick them on the machine, put them in the tool cabinet, machine operation manual or any other convenient location.  This is important because it makes ordering the next time easier, safer and allows you to order with confidence that you are getting the right knob.

Packaging counts:   Our Retention Knobs are packed individually in tubes.  Most competitors will send you a plastic bag with 10 or more pieces bouncing around in the bag.  Also, all of our retention knobs have serial number, work order number and part number Laser Marked right on the knob.  This is key information for your safety log.

Keys to remember about Toolinghouse Retention Knobs:

 - Made in USA
 - Material made in USA
 - Sockets have 1/2" drive

Warnings and Important Information you need to know:

Warning: using an incorrect retention knob may damage your machine or cause personal injury to the operator.

Retention Knobs are NOT Interchangeable: Always compare a new retention knob to the ones in the machine at the present time.  If there are no retention knobs in the machine, look in the "CNC Operators' Handbook" there should be a drawing of the correct knob.

Always Inspect a New Retention Knob:  Make sure that if hasn't been damaged during transit.

Before Installing a New Retention Knob:  Clean both the knob and the holder with solvent and blow them off with an air hose.  Inspect both items to make sure that  there are no nicks or scratches on joining surfaces.

Always Tighten Retention Knobs with a Torque Wrench: The force required is very hard to judge without a torque wrench.  A retention knob that is too loose or too tight is dangerous.

If a Retention Knob Breaks...
What will be your cost???
$5,000?  $15,000?  $20,000?  $45,000?

Retention Knob Safety:  Retention Knobs are not intended to last forever.  Your safety program MUST include Retention Knob inspections.  Knobs must be visually inspected for damage and checked for tightness every time the tool in the holder is changed.

Maintenance and Indicators:

Maintenance Schedule:  Every 2-3 years depending upon use, Knobs should be removed from the holder and Magnetic Particle Inspected.  Any Retention Knobs showing indications of cracking must be discarded.  If your machine is in a crash or releases a tool prematurely, this is an indication that either the Retention Knob Fingers, Finger Guide, Belleville Washers in the spindle or the Retention Knob is damaged.  The machine tool should NOT be used until it is inspected by Maintenance Personnel.  In this case all of the Retention Knobs in the machine should be checked for cracks or damage immediately.

Gripper Fingers Make Burnish Marks under the head of the Retention Knob. When examining Retention Knobs pay close attention to the micro inch finish of the gripper fingers.  All of the marks made by the gripper fingers should be uniform.  This indicates that the gripper fingers are in good condition.  If one mark is different than the rest, this indicates that one gripper finger is damaged or broken.

Look for Linear Indications, Cracks or Seams: Retention Knobs are held in the machine by gripper fingers that are attached to the draw bar.  Pressure is applied to the draw bar by the Belleville Washers.  This combination holds the tool in place in the machine.  This pressure is about 2800 lbs. in a 40 taper machine.  The roughing tool tries to pull the tool out of the spindle.  So, at times, the pull on a Retention Knob is greater than 2800 lbs.  Tool marks or any imperfections in the knobs finish will in time be where the tool begins to crack.  Normally a line will start to form around the knob in the direction that the machining marks are.  The longer that pressure is applied to the Retention Knob, the deeper the lines will become.  If the operator inspects the finish of the Retention Knob every time he changes tools in the machine he can be instrumental in replacing the knob before the knob fails.

Handy Reference Guide: When you order your Retention Knobs from us, be sure to ask for a free copy of "Care of Machine Spindles & Tool Holders".  It contains key information  for every set-up person and machine operator in your facility.

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