Light duty, small scale, and low torque applications can often benefit from fasteners that are able to be installed, removed, and adjusted by hand, without the use of tools.  Instead of purchasing a series of expensive custom fasteners, adding knobs to standard hex-head and socket-head hardware is the easiest way to suit these types of applications. 

What are Press-Loc Knobs?

Press-Loc Knobs are tight-tolerance hand knobs, designed to press onto fasteners for a no-slip, limited-wear interference fit over a fastener’s head.  These knobs allow users to freely adjust, install, and remove fasteners by hand, where hand-tightening alone is all that the assembly calls for in torque.  These knobs can be installed by firmly pressing them down onto the head of the fastener, and can be left in place or removed after use.   

While Press-Loc knobs are generally OK to remove when needed, there is the potential that knobs will loosen as they wear after repeated re-installation.  Socket Head style knobs tend to be more susceptible to wear and slippage over time, as they only have the friction between the knob’s inner bore and the screw’s cylindrical outer diameter to maintain a firm bond.  Hex Head style knobs are much more forgiving to long-term use, as the flat edges and distinct corners of the hex head resists wear and slippage much better. 

There are separate categories of fasteners that are manufactured with permanently mounted knobs and handles, which are more appropriate for jobs where all fasteners are routinely adjusted by hand and able to be specified to include knobs from the start.  Press-Loc Knobs are better suited to either retrofit existing fasteners by adding knobs without having to replace (or even remove) the entire fastener, or when a small quantity of knobs can be moved between multiple fasteners for infrequent use. 

Do you have a Fastener Knob application but are unsure of which fastener meets your project’s requirements?  E&T Fasteners offers expert support and product selection between the above options and more!  Contact us to discuss your application, see our Screw and Bolt catalog here, or to see our entire fastener catalog, visit our product selection here

Press-Loc Knob Styles

Press-Loc knobs are available in many different styles, sizes, and materials.  We’ll describe the most common styles below. 

wing socket head-press-loc knob Wing Socket Head Knob Wing Knobs are considered the ‘standard’ knob design, identified by their two protruding levers.  The Socket Head variant is intended to press over any standard socket head cap screw, including (and most often) serrated round thumbscrew heads.  These knobs allow for more torque and grip when operated by hand, and are also referred to as ‘Bi-Wing’ knobs.  Available for standard socket head screw sizes #10 through 5/16” diameter.     
 wing hex head press-loc knobWing Hex Head Knob With a similar, two-lever profile as the above version, these Wing Hex Head Knobs are designed to press onto hex-head bolts, hex-head screws, and hex nuts.  Available for hex-head fasteners manufactured to standard 1/4″ specs. 
 Tri-Wing Socket Head Knob Tri-Wing Knobs offer three levers for additional grip and torque when compared to the Bi-Wing styles described above.  The Tri-Wing Socket Head Knob style is designed to press onto standard socket head screws sizes #10 through 5/16”.   
 Tri-Wing Hex Head Knob Similar in design to the above Tri-Wing Thumbscrew style, this Tri-Wing Hex Head Knob instead presses onto standard 1/4″ hex head cap screws and hex nuts. 
 Round Socket Head Knob When tight space or low torque requirements steer away from large winged knobs, these Round Socket Head Knobs can be utilized to help grip screw heads in a space-conscious manner.  Designed to press onto standard socket head cap screws, these knobs are available in #4 to 5/16” diameter. 
 round hex head press-loc knobRound Hex Head Knob Pressing onto standard 1/4″ diameter hex head cap screws, bolts, slotted / unslotted screws, and nuts, these Round Hex Head Knobs provide tool-free operation in tight spaces. 
 flowerette socket head press-loc knobFlowerette Socket Head Knob Our last most common knob pattern is the Flowerette style, which features multiple finger indentations around a large-diameter knob profile for higher torques and easier gripping.  This Flowerette Socket Head Knob style is designed to press onto any standard socket head cap screw sizes 1/4″ to 3/8” diameter. 
flowerette hex head press-loc knob Flowerette Hex Head Knob Rounding out of list of knob styles, the Flowerette Hex Head Knob style fits over any standard hex head cap screws, bolts, and nuts, with all of the same higher-torque benefits of the above Socket Head style.  The Hex Head style here is available in standard 1/4″ diameter. 

Press-Loc Knob Specifications 

Press-Loc Knobs are regularly specified and available in Acetal materials, though other options are common.  Acetal is a high strength, low friction engineered plastic that has superb wear characteristics, is chemically resistant to common industrial compounds, and is easily machined to extremely tight tolerances that hold true over time.  Advanced formulations of Acetal can be specified including FDA-Compliant Food Grade, Metal and X-Ray Detectable, Static Dissipative, Enhanced Wear, and Glass-Filled variants. 

Acetal is also known under the DuPont product name Delrin, which is the formulation most Acetal fastener hardware offerings are made of.  Delrin offers a temperature range of -40*C to 120*C, and is notably well moldable directly onto metals (as found with versions of the above knobs that are factory-adhered to fasteners).

Many other materials are available as well:  Nylon, PVC, Polypropylene, Phenolic, PTFE, G10, Kel-F®, Neoprene, Mylar, Glass-Filled Nylon, Peek, CPVC, ABS, PVDF / Kynar, Isoplast, Polycarbonate, Polyethylene, or Ultem®.

Press-Loc knobs are standardly available in Black color, with Natural and White colors as the next most common selections.  Blue, Red, and Green colors are available as well, and other custom colors can be requested.  Using colored knobs is especially useful when referenced in part with Standard Operation Procedures (SOPs), training, and quality control workflows in manufacturing settings. 

Assortment Kits are available for Press-Loc Knobs as well, helping purchasers stock up for maintenance, engineering, service, school lab, and other bulk uses.  Kits are available in 144-piece up to 704-piece assortments, in all knob styles. 

Lastly, Press-Loc Knobs are available in metric sizes, as well as smaller or larger imperial sizes than the standard sizes mentioned above.  Special sizes, profiles, colors, materials, and other options can all be requested – please inquire with any special requests. 

E&T Fasteners is here to help you navigate fastener and accessory options.  Price quotes, availability, lead times, delivery confirmations, unique application suggestions – whatever your need, we’re here to take your call or email.  For support and advice from our fully trained staff, speak with an E&T sales representative today. 

About E&T Fasteners

With sales and support teams spanning the Continental US, E&T Fasteners is here to serve your hardware, fastening, and component needs both domestically and internationally.  We are a stocking distributor of metallic, plastic, and exotic alloy fasteners, backed by our technical staff directly experienced in your unique applications.  We can assist your specifying and selection efforts, providing engineered solutions, record-fast lead times, and stellar customer service from quote through delivery.  Please let us know how we can help!