Disaster! My only copy of the my car key broke, I park on the street and have to move my car by Saturday 9AM today is Friday and I have to go to work. What to do? I could call an auto locksmith or take it in to the dealer but that would be expensive and take time. There has to be a better way, I'm going to upgrade my key into the 21st century and make a 3D printed copy with Fusion360.
Fusion360 is a powerful cloud enabled 3D modeling platform, and the best part if you register as an enthusiast it's free!
Step 1: What You Will Need
The process of duplicating the key is pretty straight forward, we will use calipers and a camera to get the general geometry of the key. We will then model it in Fusion360. And finally we will print the key on a Connex500.
1 key to be duplicated
1 Object Connex500 or Shapeways
Step 2: Photograph the Key Orthagonally
The first step to making a reconstructed duplicate is to take orthogonal photos of the original. We need to get at lease one good shot of the side of the key and a basic shot of the profile of the key. These photos will be our guide for tracing and where to measure.
Lay the key down and get it as flat as you can. Try to get the light as even as you can. Take the photos from a bit further away than you think you would need to, taking them further away means the profile will appear 'flatter'. The flatter the image the more accurate the trace will be.
Open up a new design in Fusion360, in the model workspace go to the insert tab and add in your best photo of the profile.
Step 3: Model the Blank
Now that you have the photos for reference use your calipers to get a known easy to measure dimension. In this case I used the width of the key. With that dimension use the calibrate tool to scale the image so it is at the real scale of the object.
Now that the image is scaled we can start building the blank of the key. Use the calipers to measure the length and width of the key. Make a new sketch then a rectangle of the basic size of the key. Measure the keys thickest point and extrude the sketch to that volume. If you want you can also add a handle at this point.
Step 4: Model the Grooves
Next add in the grooves on the side of the key. Use the caliper to measure the distances both along the axis of the key and along the width of the gaps. Record them in a new 2D sketch.
Use your calipers to get the depth of the grooves. Extrude them down but do not subtract them yet.
The key I'm using has the same grooves on both sides, so copy the bodies you just made for the grooves and then rotate them around the center of the key, you should now have the same volumes on the top and the bottom.
Use the combine tool and the action of 'cut' to carve the tool volumes for the grooves.
Add chamfers at the end of the grooves to add additional strength.
Step 5: Model the Profile
Now that you have essential the exact same thing you would cut a key from with a machine it's time to cut the profile. The profile of the key is what does the work of moving the lock pins to the unlock position. You can see how they work in the gif above.
Turn the image of the key back on. Make a new sketch of the profile of the key. Zoom in and trace the key as carefully as you can. Accuracy is 'key' here.
Once you have the profile make a box around it to close the profile. Extrude that profile up to cut your blank.
Step 6: Finalize the Model
Add some finishing touches to your model, you could add some fillets to the handle or refine the profiles.
When you are ready use the combine tool again to join the blank and the handle.
Right click the new body and 'select save as STL'
Save the stl out to the location you want to print from.
Step 7: 3d Print the Key
Once you have the STL model it's time to move over to the printer.
You need a high resolution printer to do this, you also need durable material. You might be able to get away with using a Form1 or Ember printer, there are many resins out there but you need one with high strength since the part is small.
We used the Connex500 at the piece and the Endur polypropylene-like material. Although nowhere near as strong as metal it should be good for a couple uses.
Step 8: Test, Reprint, Test
The moment of truth. Try the key is a non-essential lock first, that way if it breaks off it's not too big of a problem. Go slow and jiggle the key if necessary.
If the lock makes marks on the key or doesn't fit then just go back and reprint.
Step 9: Make It Work!
Finally go big! You can see here I just went for it, and it worked...sort of. The key fit the lock and was able to turn, it broke when turning the additional bit to start. With the key engaged you can turn the ignition with a screwdriver (you may be able to do that without the key too).
Success (sort of) I was able to avoid a ticket and get through the weekend!
In a sense its also an epic fail, but so close, with a little bit more material innovation 3D printing a key will be a reality!
It does raise a lot of questions, how much stronger does the plastic need to be?
What would a fully 3D printed lock/key set look like?
Could metal be integrated into the plastic print to make it work better?
Could it work printer from steel?
Up next how to replace your ignition lock cylinder...