Steel Dowel Pins

Sarah
DeGuzman

Steel dowel pins align and help connect industrial plates, beams, and equipment. In this article, learn the types of steel dowel pins, dowel pin sizing charts, installation, removal, and typical applications.

Dowel pins are simple solid straight pins with chamfered ends to help in insertion and alignment. These metal dowel pins are most commonly made of steel. Grades of steel vary depending on the application. High-carbon steel, used in some dowel pins, whereas stainless steel or zinc-plated steel, used in others.

Types of Steel Dowel Pins

Standard

Standard dowel pins are used to fasten pieces and keep them aligned. The chamfered end allows for easy insertion. These steel dowel pins don’t have a

Precision

Interference fit applications benefit from precision dowel pins. The hole size, tolerance, and flexibility are all taken into consideration when designing the dowel pin.

Oversized

oversized steel dowel pin
Courtesy: MISUMI

Oversized dowel pins are 0.001 inches larger than ordinary dowel pins and also known as press-fit or repair dowel pins. This permits damaged holes to widen and make room for the replacement pin. Oversized pins may require manual hammering or pressing of the dowel pin to make the required connection.

Grooved

grooved dowel pins
Courtesy: MiSUMi

Grooved dowel pins have grooves on the side for a variety of uses. The smooth end of the pin allows the connected device to rotate freely if the tracks only run down a section of the pin. Materials can travel through these pins upon insertion. They’re perfect for putting in blind holes.

Pull-out 

pull-out dowel pin
Courtesy: Fast-n-rs

Pull-Out dowel pins include an internally threaded hole that makes them easy to remove and reuse with a regular screw or pull-out tool. They’re perfect for putting in blind holes. For easy removal, a matched wrench fits into the dowel pinhole. Pull-out dowels aren’t specified in ASTM or ASME standards, but they’re typically the same hardness as hardened ground machine dowel pins.

Function

Precision engineering applications frequently use steel dowel pins for accurate placement and alignment. They can also use as a pivot, shaft, or hinge. These dowels have chamfers at each end to enable insertion and to guide alignment. This type of dowel is also available in other metals and engineering-grade polymers.

Alternatives to steel dowel pins include roll pins (slotted or spiral), grooved pins, and cotter pins. They are usually the most precise but may not be the easiest to insert and remove.

Dowel Pin Sizing Chart

dowel pin sizing chart
Courtesy: AmesWeb

Dowel pin sizes for inch size hardened ground machine dowel pins according to ASME B18.8.2. Standard Series have primary diameters 0.0002 in. over the nominal diameter, intended for initial installations. Oversize Series have primary diameters 0.001 in. over the nominal diameter, designed for replacement use.

dowel pin diameter
Courtesy: AmesWeb

Installation of Steel Dowel Pins

Check pin and hole dimensions to ensure they are within the proper tolerance. Ensure the item with the hole either is immovable or properly secured. Clean all surfaces.

Square up the material to the hole in which it will enter. For precision fits, have gage blocks on hand. Gage blocks measure the distance a pin should enter the hole. Additionally, these blocks serve as the stopping point during the press-fit process.

dowel pin installation with gage block
Courtesy: Pinimg.com

For functional fits, tap the steel dowel pin gently with a hammer or apply pressure via a press in a consistent manner. Slow installation ensures the part will not be damaged. For a small application or tight fit, a jig may be required to support the pin during installation to ensure deflection does not occur

Removal of Steel Dowel Pins

Pulling with pliers

Small dowel pins, with diameters under 3″, may be suitable for plier removal.

removal of dowel pin with pliers
Courtesy: YouTube
  • Make sure the pin is in good shape and exposed at least 0.125 inches (0.32 cm).
  • Clamp the exposed end of the nail using a pair of pliers.
  • Without angling or wriggling the dowel pin, pull it straight out.

Using a punch or drill bit

drilling out dowel pin
Courtesy: Sawdust Girl
  • Use a tapered punch or a drill bit with a smaller diameter than the pin.
  • Inside the pin, insert the tip of the punch or the backside of the drill bit.
  • Using a hammer, tap the punch or drill bit into the pin until it is snug.
  • Using pliers, grip the dowel pin and punch or drill bit as tightly as possible.
  • Twist and wriggle the pin while drawing it out at the same time.

Mechanical Force

Large dowels require large mechanical force for removal. Mechanical force removal may occur through a specialized press tool or brute force method.

Specialized tools include hydraulic presses. These presses provide consistent pressure against a pin to facilitate removal. Other tools involve the use of air and conventional rachets. Special care should be taken to follow manufacturer’s recommendations whenever possible.

Courtesy: Bull Dog Pin Puller

The brute force method should be employed only when other tools are not available or practical. Care must be taken to ensure safe removal.

  • Secure a punch to the dowel pin.
  • Ensure the surface to be struck is properly secured to the dowel pin.
  • Wear proper personnel protection equipment
  • Strike the surface squarely as possible using a safe and ergonomic range of motion.

Applications

Dowel pins locate or hold elements together within a precision assembly or fixture as a hinge, shaft, or pivot. They see employ in a wide range of industries, including aircraft, electrical motors, hydraulic equipment, instrumentation, specialized fitting connections, machinery, and military applications. Some of the most rugged connections utilize steel dowel pins – such as a bulldozer’s track connection.

Dowel pins resist repeated insertion and removal without bending. Engineers often prefer pins because no additional fastening hardware, secondary procedures, and mating parts are required. Steel dowel pins provide the flexibility of removal while providing a strong connection on par with welding and permanent fastening methods.