Can I Install A Rivet In An Over-Sized Hole?
A common question we get from our customers is “Can I install a rivet into an over-sized hole?” We set out to find out why this was such a common question and realized that it often occurred during the drill out process. While removing a rivet is a straight forward process, it is often hard to tell by the hat what size the rivet is.
Add in other factors such as the rivet spinning or being loose during removal (we made a video on how to remove spinning rivets you can check out) and it is likely that a rivet removal can result in an oversize hole. To mitigate the risks of over-drilling we recommend always starting with a slightly smaller drill bit than you think will be necessary. This will allow you to increase the size if necessary without increasing the size of the hole itself.
Already Drilled Too Large?
What happens when the rivet is already drilled out and the hole is now too large? is there a way to install a rivet in this over-sized hole? The short answer is yes and there are three basic ways to do this.
The first option is the best option and the one you should go with if your project is being held to standards and specifications. Simply figure out which size of rivet will fit into the new larger hole and go buy one. Rivets are available in many different sizes and varieties and it is likely that you can find a larger diameter rivet that will still fit the depth of the material.
Option two will work in a pinch but we do not recommend relying on it for very long or at all if it has potential to cause harm if failure occurs. This option requires what is known as a tri-fold or exploding rivet. These rivets split out when installed into three folds that provide strong retention. Due to the three folding prongs, the grip of the rivet can be asserted across a wider surface area. This will allow the rivet to tighten against a hole that is too large for the rivet. Although hard to tell in our picture, the prongs actually started to get sucked into the hole. This type of connection is likely to loosen and should not be used for a long period.
The third option only works as long as you have access to the back of the installation surface (something not always common when dealing with rivets). This method requires the use of a rivet backup washer and a tri-fold rivet. First, insert the tri-fold rivet into the hole. Next, go to the other side of the installation and slide the rivet backup washer onto the exposed portion of the rivet. Then you need to ensure the washer stays pressed against the surface while you install it. If you do not have someone to help you, you can add a bit of glue to the washer and press it against the installation surface to hold it in place. Then install the rivet. As the three wings expand out they will grip hard against the new correctly sized backing. This results in a much stronger hold than using a tri-fold rivet without a washer.
While it is possible to use a smaller rivet in an over-sized hole, the best option is always to just buy the correct rivet for the new hole. Adding a backup washer, some glue and a tri-fold rivet will yield strong results but if the job has specific standards it needs to pass for this method will not work. Finally, you can get away with using just an exploding rivet in many cases but they should only be used short term, checked frequently and should be replaced as soon as possible.