- Removing weight from sheet metal while adding rigidity is the perfect task for a dimple die,
and in this module, we'll show you how we produce the hole and shape the dimple die flange.
A dimple die consists of the upper punch half and the lower die section half which are
machined out of a long lasting and hard wearing 4130 chromoly and can be purchased individually
or in full kits.
The flare section on a dimple die is available in 2 styles and we'll be demonstrating using
the more traditional straight flared style, rather than the radiused style that's also
prevalent in the industry.
This flare on the dimple die is the reason that the strength and rigidity is retained
while the weight saving is a product of the hole that we cut through the material.
Regardless which style of dimple die you're using though, the process is identical.
To use a dimple die on sheet metal, first we need to drill a hole in the centre of where we
want our dimple die to locate.
This can be done in 3 ways depending on the size of your dimple die.
For smaller sizes, you can use a step drill to achieve the required hole size but for larger
sizes you'll need to use either a hole saw or a hydraulic punch.
The hole saw can achieve good results, however there will usually be some amount of movement
in the hole saw that will affect the ultimate accuracy and size of your finished hole.
This tends to be magnified as the hole saw gets larger in diameter and is usually
significantly worse on cheap quality hole saws.
The other option that will produce a perfect hole every time is a hydraulic hole punch.
These are very similar the punch and flare tool that we'll look at next however they only
produce the hole without the flare.
For the purpose of this module, we'll go through the process of using a hole saw
to produce the hole for our dimple die.
We've chosen a 20 mm dimple die which means that we need a matching 20 mm hole saw.
Before drilling our hole we need to carefully mark the desired location for our hole and
centre punch it to provide an accurate reference for the pilot drill of the hole
saw to locate on.
We can secure our workpiece in a drill vice and use our drill press to drill our
20 mm hole.
With the hole complete, it will require deburring and we're now ready to locate the two halves of our
dimple die through the hole.
It should go without saying but it's important to ensure that you've fitted the correct half of
the die on the bottom and the top of your work piece to ensure that the flare will be
created in the right direction.
While you can purchase hydraulic dimple die kits, the one we're using is manually actuated
and we can use a hydraulic press to force the two halves of the dimple die together.
Alternatively, if you don't have a press then you can achieve the same result by using a
bench vice, although this requires a little bit more care in order to get great results.
You will know the process is complete when the resistance on the press or the bench vice
increases significantly.
You'll also notice that as the flare begins to form, the sheet metal will initially bow quite
significantly, however as we progress and the dimple die bottoms on the workpiece, the
material will become flat again.
It is important to stop when you reach this point or you can end up marking
softer material like aluminium.
With our first demonstration complete, we'll now have a look at the alternative to the
dimple die, the punch and flare tool, which will cut the inside diameter of the
hole and perform the flare in one process, ensuring an accurate and repeatable finish
to the hole every time.
These tools are still not entirely drill free though as we still need to start by
drilling a hole for the centre bolt to locate through.
This is essentially the same as what we've already looked at, although in this case the
centre bolt requires a 12 mm hole to pass through.
With our location marked and centre punched, we can drill a pilot hole and then follow this
up with our finished hole size.
Once deburred, we can locate the two halves of our punch and flare tool on each side of our
workpiece, taking note of the direction of the flare one again.
The tool that we're using is designed to be drawn together by tightening the threaded
bolt through the centre and this can work well, particularly on thinner or softer
materials like aluminium.
We've found though, with the larger diameter dies on thicker steel that the thread can become
damaged over time.
For this reason, we're actually going to use our press instead.
This requires a sleeve to be placed between the die and the press so that the die can be
compressed without the press contacting the bolt.
Alternatively you can purchase a hydraulic version of the punch and flare tool for just a
little bit more outlay.
Just like the dimple die, we know that the task is complete when the workpiece becomes flat
and the resistance on the press increases.
If you're intending to dimple die a series of holes, then it's important to work out the
centre spacing first to allow the clearance between the flares fouling on the dimple die
that will be pressed next to it.
That was just one module from our Motorsport Fabrication Fundamentals course.
If you're interested in learning how to fabricate components for your vehicle, then this course
is going to be perfect for you.
You'll start by learning about the various tools that you're going to need for motorsport fabrication
as well as how to use them.
You'll learn about techniques such as bending and notching tube, drilling and tapping holes
and how to use dimple dies.
You'll also learn about MIG and TIG welding which are both popular techniques for welding
in the world of motorsport fabrication.
While you don't need to be a mechanical engineer or have a degree to fabricate parts, you'll also
learn some fundamentals of design so that you're able to design and fabricate strong and
reliable parts.
All of this knowledge is then tied together with a range of worked examples so you can
see how these skills and techniques are put to use with real world fabrication projects.
If you're a motorsport enthusiast and you want to expand your skillset so that you can start
fabricating parts for your vehicle, our Motorsport Fabrication Fundamentals course is perfect
for you.
If you'd like to find out more about this course, click the link in the description.