DOWEL PIN REFERENCE GUIDE

Huyett offers over 2,000 different dowel pins to suit your specific application, which can seem overwhelming. Metal dowel pins come in a variety of styles, sizes, and materials. But never fear, your friends at Huyett are here to guide you through the selection process.

What is a Dowel Pin?

Dowel pins are sometimes referred to as straight pins or lock pins. In a manufacturing setting, dowel pins are solid, headless, cylindrical metal rods that have been machined to specific tolerances. These pins are typically used to align, locate, or join components to absorb lateral stress. However, they can also be used as a pivot, shaft, or hinge. Metal dowel pins are popular for manufacturing, metalworking, and precision engineering applications in many industries, such as: automotive, aerospace, tool and die, prototyping, electrical components, and military. 

Why Use Metal Dowel Pins?

Dowel pins are a simple, effective, and versatile fastener for many assembly processes. Here are some of the more important advantages of metal dowel pins: 

• Precision tolerances provide repeatable installation results in high volume production environments
• Prevents lateral movement of adjoined components
• No addition mating hardware required
• Bevel/chamfer or tapered end guides pin to hole
• Radius end resists part deformation during installation

How to Choose the Correct Dowel Pin

Review the following list to identify the most important selection criteria when determining the best metal dowel pin for your specific application. These considerations cover a wide variety of application needs. If you have a special need that is not covered below, please let one of our skilled team members help you quote a custom part to suit your needs. 

Nine Basic Dowel Pin Selection Considerations

Here are nine basic criteria to help you narrow down your dowel pin selection. 

1. Metal Dowel Pin Sizes

How do I measure a standard dowel pin?

Dowel pin sizes are measured with a caliper to determine the diameter and end‑to‑end length of the dowel pin, including the crowns. Please view our video below if you would like to see how easy it is to measure a standard dowel pin. 

How to Measure Dowel Pins

How do I measure a DIN 7 dowel pin?

DIN 7 metal dowel pins are still measured with a caliper to determine the diameter, similar to standard pins. However, the length of the dowel pin is measured from edge‑to‑edge, not end‑to‑end. This means that the length of the pin does not include the crowns, only the length that conforms to the diameter. 

Check out our video: How to Measure a DIN 7 Dowel Pin

What sizes of dowel pins are offered by Huyett?

We offer inch or imperial dowel pins in diameters from 1/64-inch (0.0156") to 1-1/2-inch (1.5") and lengths from 3/32-inch (0.094") to 2-inch (2"). We offer metric sizes in diameters from 0.8mm to 30mm and lengths from 3mm to 180mm. 

2. Standards

What dowel pin standards are available from Huyett?

• ASME B18.8.2
• DIN 7
• DIN 6325
• DIN 7979D
• ISO 8734
• MS 16555
• MS 16556

3. Fit (Fitment) - Press Fit versus Slip Fit

What is a press fit dowel pin?

Press fit dowel pins are metal dowel pins that have a slightly oversized tolerance and are designed for use with a hole that is slightly smaller than the pin diameter. This difference in pin diameter and hole diameter is called interference, which creates tension of the pin in the hole to limit movement. Press fit dowel pins are used in precision assemblies where close tolerance alignment of components is critical. 

What is a slip fit dowel pin?

Slip fit dowel pins are metal dowel pins that slide freely in the hole with no special tools.

What tool do I use to install a metal dowel pin?

Use an arbor press to properly install press fit dowel pins. Never use hammers, as they may damage the pin, causing it to fail. 

Slip fit dowel pins have some play when installed and can be easily installed by hand. 

4. Tolerances

Should I specify a diameter tolerance when ordering metal pins?

• If the tolerance of the metal dowel pin is dictated by the standard to which it is manufactured, then you do not need to mention the tolerance at time of order. Most standards specify slightly oversized tolerances, which are suitable for original equipment manufacturers.
• If you order a non‑standard pin, then you should take into account the consistency of the holes provided in your assembly and specify a tolerance that will meet the needs of your application.
• Oversized tolerances are different from press fit (slightly oversized) pins. Oversized pins can be ordered for use in repair operations where the original hole has been enlarged by interference due to the installation of a press fit metal dowel pin.
• Undersized pins should be specified for applications where a hole with consistent diameter cannot be produced.

5. Material Type

What material types does Huyett offer for metal dowel pins?

The material for your dowel pins should be determined by your application. The host material of the hole, exposure to moisture, and other factors can help determine which material to choose when selecting the correct metal dowel pin. Please ensure the pin selected is harder than host material. Here is a list of dowel pin materials available from Huyett: 

• Carbon steel dowel pins
• Alloy steel dowel pins
• Stainless steel dowel pins (303, 316, and 416 stainless steel)
• Brass dowel pins
• Aluminum dowel pins
• Hardened or unhardened

Why choose hardened steel dowel pins?

Hardening metal dowel pins resists deformation due to interference of slightly oversized pins during the installation process. Since deformed pins can lead to failure, hardened metal dowels strengthen finished assemblies when used in conjunction with other types of fasteners. Remember, dowel pins are used to align components or act as a pivot point. They do not have features that hold components together. 

6. End Styles

What end styles are available for metal dowel pins?

• Chamfer end, or beveled end, dowel pins have a slight taper at the end that acts as a guide that more easily locates the hole for installation.
• Radius end dowel pins have a rounded crown that prevents pin deformation during installation.

7. Removable Metal Dowel Pins

What if I need to remove a dowel pin from an assembly?

Pull out dowel pins have an internally threaded hole on one end that allows for installation of a bolt and washers to assist in removal of the solid dowel pin. Once the bolt is installed in the hole, removal of the pin can be performed with pliers, vice grips or a special dowel pin puller. Pullout dowels are recommended when installed flush with a blind hole. 

8. Gas or Liquid Exchange

How do I prevent air from being trapped during installation of a metal dowel pin?

• Grooved dowel pins feature an internally threaded hole on one end, similar to a pullout dowel. External grooves are cut in a spiral along the entire length which allows gas or liquid to escape during insertion while maintaining a 360° circumference contact.
• Flat vent dowel pins are identical to pullout dowel pins with the added feature of a narrow, ground flat side that allows gas or liquid to escape while the medium is displaced during insertion.
• The venting properties of both grooved and flat vent metal dowel pins also reduce the suction that normally occurs when a solid metal dowel pin is removed from a blind hole that cannot otherwise vent.

9. Hollow Dowel Pins

What is a hollow dowel pin?

Hollow dowel pins, sometimes referred to as dowel bushings, spring alignment dowels or ground hollow dowels, are typically used as a locating device for components where precision alignment is required.

Why should I use a hollow dowel pin?

• Hollow dowels permit insertion of a traditional fastener like a bolt or clevis pin to limit axial movement of components.
• The hollow interior of the dowel can eliminate the need for a separate hole to be drilled and can act as a conduit for wiring or tubing.
• Hollow dowel pins are much lighter than solid pins and can reduce the weight of the total assembly.

Different Types of Dowel Pins

Huyett offers a range of dowel pins to accommodate different application requirements.  

Flat Vent Dowel Pins

Flat vent dowel pins have a small flat side that runs the entire length of the pin. This allows the assembly to release gas, liquid, or air after installation, because the flat edge leaves a space between it and the shaft surface. They also feature chamfered ends for easy insertion and internal threads that connect to slide hammers for easy removal.

Grooved Dowel Pins

Grooved dowel pins feature spiraled grooves, or flutes, that aid in installation. When the pin is inserted into the mating hole, the grooves are pressed shut against each other; this creates extra tension to keep the pin in place.  

Ground Hollow Dowel Pins

Ground hollow dowel pins feature a hollow center with chamfered ends. Much like a standard dowel pin, they are often used for precision alignment and centerline tolerancing. The two main advantages of the hollow center are: 1) the lighter weight; and 2) the ability to thread additional fasteners, like bolts, through the middle.  

Pullout Dowel Pins

Pullout dowel pins have a smooth outer surface and chamfered ends, but their defining feature is the internal threads on one end. These threads are designed to attach to a slide hammer that can remove the pin; this is ideal for applications that only provide access to one side.

Standard Dowel Pins

Standard dowel pins have the most basic design of the different types, which makes them versatile across a wide range of applications. They are simply a smooth, solid, cylindrical rod with different available end types (flat, chamfered, etc.) that are used for precision alignment. 

Learn More About Our Selection Of Pins Here