Make a Cheap Dimple Die for Metal Panels

[goodfellow]

Note: This die was made to form thin aluminum panels. You could use the same design and make it out of steel to use for forming steel panels.

When making brackets out of light gauge metals, it's often a good idea to consider not only form, but also function. To that end, increasing the strength of the material with a simple dimple hole pattern not only makes the part look better, but more importantly, it also increases its safety factor.

Here is a very simple small dimple die that can easily be made in an hour or so. It's made from aluminum and will make dimples in light gauge sheet steel, brass, copper and aluminum. I've made dozens of these over the years and they work well. Although they don't last as long as steel dies, they are much easier to make and reshape -- if the need arises.

The hardest part in making a die like this is grinding precise concave and convex HSS lathe toolbits for forming the dimple radius on the die.

These specific dies makes 3/4" OD dimples -- the stock is 1.5" aluminum bar.

First cut two 2.5" slugs and face the ends.





Next take two blank HSS lathe bits and grind the internal and external profiles (same radius on both) for the flages that will impart the shape (dimple) to the sheet metal stock. This is difficult at first, but can be readily mastered in a short time. The important thing in grinding HSS is not to let the bit overheat and to grind only a few seconds at a time. Keep a cup of cold water handy to keep the bit from overheating.

For further info on grinding lathe bits -- start here!  http://www.sherline.com/grinding.htm

Here are my finished bits (one for the "receiving" die flange and the other for the "pressing" die flange) the radius is the same. The relief angle on HSS bits is not that critical if you're machining aluminum. Another reason to make dimple dies out of aluminum instead of steel.





First drill the 1/2" pilot hole in the receiving die and use the concave profile bit to machine the inside radius. This is fairly easy because the 1/2 drill will make a pilot hole just a bit larger than 1/2" -- which will allow the precisely machines pressing die to slide easily in and out.





Using the HSS bit, the Inside flange is done --  a straight forward process.



Next use the other slug to machine the pressing die (the shaft will be exactly 1/2") -- much more precison is required at this stage.







On my initial setup, I machined a little 1/8" step in the bottom of the pressing and receiving dies to assure a tight fit, but in retrospect it's not really necessary.

Now it's time for the convex bit to machine the shoulder of the pressing die. Patience and frequent measuring pays off at this stage











Finished pressing die looks like this (notice the small step at the top. It doesn't help much, and takes too much time to machine on the receiving die)




The completed set -- it can be used successfully in an arbor press, hydraulic press, or even in a big vise -- I've made successful dimples with all of these methods.




Hope some of you guys give it a try!!!