Dowel Pin Design Guide

Date: April 09, 2024

While some basic dowel pin requirements are easy to identify, if even one specification is missed it will result in a poor application fit. Use this guide to inform your dowel pin selection, or reach out to our technical support team with questions.

Berg offers more than 150 unique dowel pins in different sizes and materials.

How to Choose the Right Dowel Pin for Your Application

WM Berg steel dowel pins are used in a wide range of precision engineering applications and industries, including aerospace, healthcare, motion control, manufacturing and defense (military). There are several selection criteria to consider when selecting a machine dowel pin for a specific application.

machine dowel pins in three different sizes


Dowel pin sizing relies on two measurements: outer diameter (O.D.) and length.

WM Berg manufactures dowel pins in the following sizes:

  • O.D. from 0.0312 - 0.4999 inches (0.8 - 12 mm)
    • O.D. tolerance is +/- .0001
  • Lengths from ¼ - 2 inches (6.35 - 50.8 mm)
    • Length tolerance is +/- .010

Tolerance & Fit

Choose your O.D. based on whether your application calls for a press fit or a slip fit.

Press fit dowel pins (installed using an arbor press) are made with a slightly oversized tolerance because they need to fit tightly without any wiggle room after installation. Specify press fit if your application involves precision assemblies requiring close tolerance alignment of components.

Slip fit (aka loose fit) dowel pins can slide into or out of the hole and don’t need any tools to be installed. Specify slip fit if you are designing a self-locating assembly.

End Styles

There are two dowel pin end styles available from WM Berg:

Chamfer end: Slight taper (bevel) helps guide pin into hole.

Radius end: Only available for metric dowel pins. Rounded (radiused) end removes sharp edges which prevents distortion during installation.

dowel pin diagram with dimensions, radius end and chamfer end labeled


WM Berg manufactures precision dowel pins using any of these three standards:

  • American standards
  • European standards
  • Military standards

American dowel pin standards

The American National Standards Institute (ANSI) standard for dowel pins (B18.8.2) includes two diameter series:

  • Standard Series: diameter is +0.0002 inch over nominal diameter (for initial installations)
  • Oversize Series: diameter is +0.001 inch over nominal diameter (for replacement use)

ANSI dowel pin lengths have a tolerance of +/- 0.010” and increase in:

  • 1/16” increments up to ⅜”
  • ⅛” increments from ⅜” to 1”
  • ¼” increments from 1” to 2”
  • ½” increments above 2 ½”

Length tolerance is +/-0.010”

dowel pin engineering drawing with diameter and length tolerances labeled

Image credit: Engineers Edge

ASME/ANSI machine dowel pins chart for precision imperial (inch) dowel pins:

ASME/ANSI machine dowel pins chart with sizes in inches

*Nonpreferred sizes (not recommended for new designs)

Dimensions for American National Standard Hardened Ground Machine Dowel Pins per ANSI/ASME B18.8.2

European dowel pin standards

The International Organization for Standardization (ISO) standards for dowel pins specifies characteristics of steel dowel pins from 1mm to 20mm (both inclusive).

The ISO 8734 standard for dowel pins is currently equivalent to DIN EN 28734, which is a standard from the German Institute for Standardization.

ANSI and DIN are both members of the ISO, which is a worldwide non-governmental organization.

engineering drawing of machine dowel pin with dimensions and tolerances labeled

Image credit: Engineers Edge

Metric Dowel Pins Chart per DIN EN ISO 8734:

metric dowel pins chart showing DIN EN ISO 8734 tolerances

Military dowel pin standards

The Mil. Spec. dowel pin standard is NASM16555 (previously MS16555): Pin, Straight, Headless (DOWEL) (.0002 Over Nominal Size).

Mil-P-21143/2 specifies undersize dowel pins with a basic diameter of -0.0002 Under Size: Pin, Straight, Headless (DOWEL) (.0002 Under Size), CRES 303.

Mil. Spec. standardization is used for components used in applications within U.S. Military Departments and Defense Agencies to limit and streamline the number of items in the military supply system.

WM Berg can manufacture dowel pins meeting dimensional standards set by ANSI/ASME, ISO, DIN or Mil. Spec. Please be sure to specify which standard you need when requesting a quote.


WM Berg manufactures precision steel dowel pins using three types of material:

  • 303 stainless steel
  • 416 stainless steel
  • Carbon steel

Proper material selection is critical to dowel pin performance and longevity. It’s important to specify the dowel pin material as determined by your application. For example, stainless steel provides rust protection for applications where contamination is not allowed.

303 stainless steel dowel pins

303 stainless steel is not hardened, but it is strong, with high resistance to heat and corrosion.

416 stainless steel dowel pins (hardened)

416 stainless steel has a Rockwell hardness rating of C36-42 and conforms to Mil. Standard NASM 16555 (MS16555).

Carbon steel dowel pins (hardened)

Carbon steel is carbonized with a Rockwell hardness rating of C58-62 and available with a case depth of .010 to .020 inch.

Hardened vs. “soft” steel dowel pins

Hardened steel dowel pins offer greater resistance to deformation. This is an important consideration when:

  1. Your application calls for slightly oversized dowel pins: the installation process may cause deformation of non-hardened steel
  2. Your assembly uses multiple types of fasteners: hardened steel dowel pins provide greater strength to the assembly when used as pivot points or to align other assembly components

Hard dowel pins are made from 400 series stainless steel because it can be hardened. Soft dowel pins are made from 300 series stainless steel because it cannot be heat treated harder.

Non-hardened steel dowel pins offer greater corrosion resistance. This is an advantage when your application is in a corrosive environment such as:

  • Coastal/marine outdoor settings with salt, humidity, precipitation & atmospheric pollutants
  • Factory or plant with airborne contaminants (industrial gasses & dust particles)
  • Agricultural/rural outdoor settings with exposure to nitrates, ammonia & diesel fuel
  • Mining, mineral processing, oil & gas & other industries where equipment is underground/in contact with soil
  • Water/wastewater treatment, desalination, food & beverage & other industries where equipment is in contact with water

Shop WM Berg Dowel Pins

Shop our selection of dowel pins and filter by style (dowel or soft dowel), material and diameter. Each unique dowel pin part page features a free CAD tool to generate a 3D part configuration. Dowel pins are sold in packages of 10, and we also offer dowel pin kits with assorted sizes.

Shop Dowel Pins

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