Automotive

How To Replace a Dowel Shaft

In high-precision equipment, such as motors, gearboxes, and other drive components, dowel pins and shafts are both commonplace components. Components may be hinged, driven, rotated, or located with either one, and both are able to withstand repetitive insertion and withdrawal without being distorted. Shafts, including the shaft anti-rotate with dowel key, are often longer in length and have a greater diameter than precise dowel pins, which is the fundamental distinction between these two types of fasteners. 

Dowels are often employed to connect components in a fixed spot, limiting the impacts of high torque and high vibration applications, as well as problems associated with radial or axial movement. Shafts, just like an anti-shaft rotation with a dowel key, the other hand, are used frequently to transfer rotational or linear motion. Scroll down below to find the article that is most relevant to your situation if you are having trouble removing the dowel pins and shafts. 

What is a Dowel Pin?

Dowel pins are used to maintain the correct alignment of machine components; they are also used as guides for locations to the neighboring machine parts and to maintain the alignment of the two portions of a punch and die. Dowel pins are made of a material that is hardened and precisely formed. Dowel pins are produced using pneumatic dowel equipment, and they are sold with their lengths and diameters already cut to the appropriate dimensions. These dowel pins find usage in a wide variety of applications, including strengthened joints, shelf support, and a variety of applications utilized by hobbyists. 

Stainless steel Dowel Pins come in a variety of grades that are resistant to corrosion. We advocate using 316 stainless steel in locations where a very resistant product is required, such as salt water, since it has excellent corrosion resistance. The 18-8 and 304 grades of stainless steel both contain properties that make them resistant to corrosion and are thus regarded as the industry standard.

What is the Purpose of Dowel Pins?

There are a few other names for dowel pins, including lock pins and straight pins. Dowel pins are solid cylinders made of metal that lack any kind of head and have been machined to exacting standards for use in the manufacturing industry. Pins like this are frequently used in order to align, locate, or attach components in order to alleviate lateral tension. On the other hand, they may also serve the function of a shaft, a pivot, or a hinge. Dowel pins made of metal are often used in the fabrication, metalworking, and precision engineering processes across a wide range of sectors, including the automotive, aerospace, tool and die, prototype, electrical components, and military markets.

Why Use Metal Dowel Pins?

In many different types of assembly procedures, dowel pins may be used as a basic, reliable, and adaptable kind of fastener. Repeatable installation outcomes may be achieved even in high-volume manufacturing situations thanks to precise tolerances. The following are the most significant benefits that may be gained by using metal dowel pins:

  • It impedes the mobility of components that are next to one another laterally;
  • There is no need for any additional mating hardware;
  • Pin-to-hole end guides with a bevel, chamfer, or tapered end;
  • The radius end prevents the component from deforming while it is being installed.

Choosing the Right Dowel Pin

Read through the list below to find the most important aspects when choosing the best metal dowel pin for your needs. These things to think about cover a wide range of application requirements.

1. Metal Dowel Pin Sizes

A caliper is used to measure the diameter and the length from one end to the other, including the crowns, of a dowel pin. If you want to see how easy it is to measure a standard dowel pin, watch the video below. The diameter of DIN 7 metal dowel pins is still measured with a caliper, just like standard pins. But the dowel pin’s length is measured from edge to edge, not from end to end. This means that the crowns are not counted in the length of the pin. Only the length that fits the diameter is counted.

2. Fit (Fitment) – Press Fit vs. Slip Fit

Press-fit dowel pins are metal dowel pins that are a little bit bigger than they need to be and are meant to go into a hole that is a little bit smaller than the diameter of the pin. This difference between the size of the pin and the size of the hole is called interference, and it makes the pin tight in the hole so that it can’t move. Press-fit dowel pins are used in precise assemblies where the parts must be aligned to a very small degree of error. Slip-fit dowel pins, on the other hand, are metal dowel pins that can slide into the hole without any special tools.

3. Tolerances

If the metal dowel pin’s tolerance is set by the standard to which it is made, you don’t need to say anything about the tolerance when you place your order. Most standards have tolerances that are a little bit bigger than what original equipment manufacturers need. If you order a non-standard pin, you should make sure the holes in your assembly are all the same size and give a tolerance that works for your application. Oversized tolerances are not the same as press-fit pins that are just a little bit too big. You can order larger pins to use in repairs where a press-fit metal dowel pin has caused the original hole to get bigger. In situations where a hole with a consistent diameter can’t be made, undersized pins should be used.

4. Type of Material

Your application should tell you what kind of material you should use for your dowel pins. When choosing the right metal dowel pin, the material of the hole’s host, the amount of moisture it will be exposed to, and other things can help you decide which material to use. When you harden metal dowel pins, they are less likely to bend when slightly larger pins hit them during installation. Since bent pins can cause failure, hardened metal dowels are used with other types of fasteners to make finished assemblies stronger. Don’t forget that dowel pins are used to align parts or serve as pivot points. They don’t have things that keep parts together. 

  • Pull-out dowel pins have a hole on one end that is internally threaded so that a bolt and washers can be used to help pull out the solid dowel pin. Once the bolt is in the hole, the pin can be pulled out with pliers, vice grips, or a tool made just for that purpose. When put in flush with a blind hole, pullout dowels are the best choice. 
  • Hollow dowel pins, which are also sometimes called dowel bushings, spring alignment dowels, or ground hollow dowels, are usually used to locate parts that need to be perfectly aligned.

5. Gas or Liquid Exchange

Grooved dowel pins have a hole on one end that is internally threaded, like a pullout dowel. External grooves are cut in a spiral pattern along the whole length of the tube. This lets gas or liquid escape when the tube is inserted while still making contact with the entire circumference. Flat vent dowel pins are the same as pullout dowel pins, but they have a narrow, flat ground side that lets gas or liquid escape while the medium is being pushed out of the way during insertion. Both grooved vent and flat vent metal dowel pins reduce the suction that happens when a solid metal dowel pin is taken out of a blind hole that can’t vent otherwise.

How To Replace a Dowel Shaft

The following are some of the methods and/or techniques of removing dowel pins to replace dowel shafts:

  • The first way is to pull

If your dowel pin is still whole, has at least 0.125″ of exposed length, and is not near a feature with tight tolerances, the Pull Method may be the fastest and easiest way to do it. First, put the piece in a vise. Then, use a precision tool like a chuck or pin vise to hold the dowel pin while you pull it out. Lastly, pull the pin away from the part, making sure not to tilt the pin as you pull it out. 

  • Drill, tap and pull out

If method 1 doesn’t work or the pin is in a tight spot, you can use a tap to take it out. First, put the part on a prototrak and line it up. Drill a hole in the pin and tap it with the largest tap that will fit inside the pin’s diameter. Once the tap has hit bottom or you’ve reached the right depth, just move the ‘z’ height back on your machine to take out the dowel pin. Even though this method works, it can be hard to do and may damage your tap. If you can, please try method 1 first.

  • Push Out Method

If a dowel pin is stuck in a hole that goes all the way through, try to push the pin through the whole part. To employ this method, you will need a pin that is smaller than the pin you want to remove. Next, put the part on your prototrak so that the smaller pin will go into the hole that is blocked. Then, lower your machine’s “z” height and use the smaller pin to push the stuck dowel pin out. This method will change the shape of the whole hole, but the workpiece will still be usable, and the dowel pin can be taken out.

Editor’s Take

Dowel pin removal may be challenging but is sometimes required. There are many potential causes for a dowel pin to get jammed within a component, so it’s important to assess the issue thoroughly before trying removal. Use extreme caution while using any of these techniques, and make periodic checks to make sure you aren’t ruining your work or the equipment. Don’t hesitate to post a question or remark if something is unclear. For more information, visit https://www.fortune-cross.com/th/.

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