Tech Tip- Making Dimple Holes without a Press

Posted: April 10, 2015 By: MattM

Dimpled or flared holes in panels not only strengthens the panel, but also adds a “industrial” look to a panel that is really hot right now. This process dates back to the WWII era when panels for aircraft were done this way to add strength and save weight. That look trickled down to post-war race cars and eventually has become mainstream in styling into custom cars.

The tools to do this process are quite expensive and some even require a press to punch and flare the holes. I picked up this cool trick from another builder online and tried it out myself and share with everyone here.

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The first step is to drill a hole with a hole saw or a greenlee style knockout punch can be used. I chose to make a 1.5″ hole in this 18 gauge panel.

Photo Apr 03, 1 11 54 PM

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Once the hole was made I supported the panel from underneath with piece of pipe slightly larger than the hole I had drilled. I then took a teardrop nylon mallet and put the tapered end into the 1.5″ hole. I then took a flat round nylon hammer and hit on the large side of the teardrop hammer a few times quite hard.

Photo Apr 03, 1 12 57 PM

What happens is the tapered part of the teardrop hammer is forced into the hole and gently flares the hole open. This creates the same look as with the expensive tools. The difficult parts of this process is repeating the same depth flare and holding the hammer square so you get an even flare around the diameter.

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The results are pretty good and if you practiced technique enough you could repeat the same flare over and over again. I would only suggest this on thin gauge sheet metal like 18 gauge mild steel and down. This is a cool free trick that I’ve now put in my arsenal for future use and I hope you can do the same!

-Matt/EW

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