Egg Cracker No Blade V2

In this Instructable I will show you how I designed and 3D Printed an egg cracker, this is the V2 version and much improved.

I'm by no means an expert using Fusion 360 but I am getting there, this is only my interpretation of the way I would design a model.

Why the need for an egg cracker you might say?

I've really struggled over the years to crack the humble egg, be it into a frying pan or bowl etc, 9 times out of 10 I will break the yolk Grrrr! I watch people do it with a tap and one hand, or just a tap and pull the shell apart, it all looks very easy, well not for me, it may be because I don't have long nails, I dunno! anyway it's definitely frustrating and If ever I needed a gadget then here it is, it's my Fusion 360 designed blade less Egg Cracker, when I say blade less it's because there are egg crackers out there with 2 metal blades, these don't retract or anything so I'm thinking if people aren't careful they could cut themselves when cleaning the cracker, this version has 2 very fine tapers which penetrate the shell, and these are used to open the shell as well.

The crackers works by putting an egg into the jaws and then screw the push component out until it secures the egg, then holding the 2 sides of the cracker, the handles are squeezed until the tapered points pierce the shell, you then squeeze the handles and the egg will drop into your frying pan or bowl, cup etc, turn the cracker 180 degrees to discard the shell.

This features of this cracker are:

Only 6 Components

Easy to remove supports.

Limited hardware.

Very little clean up.

No sharp Metal blades.

Adjustable plunger for variable egg sizes.

Comfortable grip.

Easy to clean.

Inexpensive to make.

Winner Winner Chicken dinner as they say :))

Well the proof is in the eating so onto the Instructable.

3D Printer

PLA Filament 1.75

M3 x 20mm Allen Head set screw x 4no

M3 x 14 or 15mm Allen Head set screw x 1no

5no M3 Locking Nuts.

1 M3 Washer.

2 x Small Elastic Bands.

Eggs

Many people I know will be familiar with Fusion 360 so I'm not going into the full details of how to create a component and start a new sketch, there are many tutorials out there that can explain it far better than me, but the first thing I did was look online for a free image of an egg, with this downloaded we can now insert it into our sketch and using the Canvas Calibration tool we can set the dimension of the egg at a height of 62mm this is a standard large egg size.

The next task is to create a sketch on the same plane as the canvas and sketch a vertical line the length of the egg image, we can now use the spline tool to trace one side of the egg, use the mouse wheel to zoom in to be more precise, when the line is complete end to end, we can now use the solid tab then the revolve tool, this will give us the solid egg body to work with in the design, make the body into a component and name it.

In this section we look into creating the basic shape of the egg cracker and the principles of how this would work.

Fortunately there are some manufactured egg crackers out there which can give us the basic shape we need, and also the principle, I tried a few sketches before selecting this particular design.

You can apply artistic licence and make it your own unique design, I try to design using the least number of components to stop myself from getting confused with sketches bodies and components, they can soon mount up in the browser.

I think about the dimensions of the cracker and what would be comfortable to hold.

I seldom use pencil sketches, a lot of this is trial and error so with the egg in the design we can make our sketch and extrude to a depth we are comfortable with.

The thing to remember when using Fusion 360 is that when you want to sketch a body onto another body, then you can use a face of the model you want to attach or create an offset plane, or any plane from the drop down list, so you are building onto an existing body.

Another thing to remember is that we only need to design one handle as the opposite side will be mirrored as they are identical.

The next task is to add the mounts firstly for the center piece, this is the component where the plunger will slide up and down, this is sketched from the top of the handle, the sketch is then extruded the full depth of the handle, then we stop sketch and use the end of the newly extruded part, to sketch a rectangle or square to this to create a cut out in which the center component will fit.

The same applies to the next mount which will be for the lever which pushes the plunger.

I leave adding fillets etc until the component is finished, when I am happy that no adjustments need to made then I can add them.

Think ahead and look at the model and think where the cracker might need more strength, gussets can be added, check out the screen shots of my model and where gussets were added.

To add gussets mid way on the model, find the depth of the component and create an off set plane from the top of the face to that depth, sketch your gusset with the sketch entering the component, and extrude symmetrically to the depth you want the gusset, you can then add fillets.

I find that an offset of approx 0.2mm is good for moving parts, like the levers that push the slider up and down, these need to be free for the action to work smoothly.

I created an offset from the top face for the component which the elastic band attaches to, adding a recess to hold the band in place.

I created the holes and recess's for the 3mm Allen head set screws and lock nuts, I want both the bolt and nut to be sunk into the handle, create a six sided polygon to create the hexagon shape for the lock nut, measure a lock nut and remember to add an offset to the dimension.

The final image in this section is the left handle which is complete, the next stage is to mirror that handle so we have a pair, then we can add the components to complete the cracker.

In this section we create the center piece of the cracker and also the components that make the plunger work.

We have to mirror the left handle, and to do this I used the flat face of the part that enters the egg mirror from this point and save as a new body.

With the 2 handles we can now create the center component, this is the part that the sliding plunger runs through, think about the scissor action, and how it will work, also think about how the part will print.

Off set the face of the lower bracket and off set to 0.2mm and sketch the shape of the component, extrude and fillet and make any adjustments, save as a new body.

I then created the plunger and the threaded top piece, threads are easy with Fusion 360 but I always off set the threads on both the male and female for 3D printed, I off set each face to -0.1 with this and using a fillet it makes for an easier thread to screw in and out.

Think about how the scissor action will work to push the plunger up, the easiest thing here is to look at the screenshots of the design stage and see how parts are added.

That is the egg cracker completed.

To complete this Instructable I assembled the cracker with the 3mm hardware, and the elastic bands, the recess's for the Hexagon nuts were too tight, I off set the faces and re printed, this modification worked great, the scissor action didn't work as it should so I modified both the plunger and the push rods, this worked well.

To use the cracker, in the closed position, you place an egg in the jaws, you then screw the recessed thumb turn until it secures the egg, holding the 2 sides of the jaws you squeeze the handles until the cracker pierces the shell, release the jaws and squeeze the handles fully to release the intact yolk, turn the cracker 180 degrees to eject the shell.

I designed and printed a simple wall mounted holder for the cracker with the words "It's a Cracker!" embossed on the face.

So there you have it, a gadget which has improved my egg cracking skills 100%

As always thanks for looking.