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  • #9430

    Hello all,


    This design challenge is about creating a mechanical tap extender/adapter which can be attached to the front of a smartphone to allow the end user perform “Back Tap” actions without the need to hold the phone or access the back of the device. This can potentially be achieved using a lever arm mechanism which can be used to tap the back of the device from front or sides.

    “Back Tap” actions can then be mapped to custom tasks through the Operating System.

    ![mechanism|666×500, 75%](upload://LRt6cwAGlZBXNM4Vas02RVch7j.png)


    Recently (2020), Apple has released iOS14 which comes with new accessibility features including “Back Tap” feature. This feature allows the user to perform custom tasks by double tapping or triple tapping the back of iPhone. You can also use these back tap actions to activate shortcuts or launch apps such as Google Assistant.

    This feature is also available in Android 11 for new line of Pixel devices.

    **Hardware Availability:**

    Apple iPhone: iPhone 8, iPhone 8 Plus, iPhone X, iPhone XS, iPhone XS Max, iPhone XR, iPhone 11, iPhone 11 Pro, and iPhone 11 Pro Max, iPhone 12 , iPhone 12 Pro, iPhone 12 Mini

    Google Pixel: Pixel 4, Pixel 5

    **Software Availability:**

    iOS 14,Android 11


    Apple iPhone: The feature is available on iOS 14 via Settings > Accessibility > Back Tap.


    iOS 14: How to use iPhone Back Tap custom controls for Shortcuts, Accessibility, system actions



    **Hi Milad,**

    I am trying to design something for this idea. Will see if that could be useful.

    **Gurbaksh Singh | India**


    **Hi Milad,**

    I know it’s not a perfect design, but just out of my curiosity and interest in 3D modelling i tried to make this in reference with iphone8.

    Here are few of the design pics:

    ![bottom|459×500, 75%](upload://Asix6Kj9aHXOVdEcMkfUorlwzea.jpeg) ![side|623×310, 75%](upload://o7mSdzTaLz4SwNLN5K0X2e1icvv.jpeg) ![side1|572×384, 75%](upload://txFXUZwifYw0BZonl3NUhxVFcB3.jpeg) ![side2|526×462, 75%](upload://3pwr1jQH1jTh9K2yY1zm8JziCdV.jpeg) ![side3|447×448, 75%](upload://50vMZa4NdszpqX5mPqRIG2N91Rf.jpeg) ![top|364×500, 100%](upload://5qmyr3wz8SA2Z0ViFLxUR7hVIN6.jpeg)

    Please do provide your feedback for any kind of improvements, i will try to fix it.!!

    **Gurbaksh Singh**


    Hi Gurbaksh,

    Thank you so much for taking on this challenge idea.

    I like your design and the first design iteration looks promising.

    Three suggestions:
    1) Probably want to use a spring or some mechanism to return the lever back when released. The spring tension should not be very default to double press however.
    2) It would be great if the holding component can be replaced for different phone thicknesses and phone cases.
    3) You may want to add some indent to surface touching the back of phone. This may not be necessary and can probably tell if it’s needed after first print.

    I appreciate taking time to work on this challenge and looking forward to see the next iteration of your design.



    **Hi Milad,**

    Thanks for your feedback..!!

    **1.** Yes, i was considering the soft spring mechanism for the liver, so it will return the lever back automatically. As it’s just a first version, i just wanted to confirm whether this kind of design will be feasible or not at all.

    **2.** Yes, i will try to make it detachable type, so that the mobile holder part could be easily replaced as per the smartphone design.

    **3.** Ok. i will update that pointed edge to a smoother one and send you 2nd version of this sooner.

    **Thank You..!!**

    **Gurbaksh Singh**


    Great stuff. I am looking forward to see your updated design.

    Thanks again.


    **Hi Milad,**

    Have a look at this newer version,i have tried to make it customizable, so it can be snapped to any smartphone.

    * The Two Yellow parts will be used to hold the smartphone using a Nut and Bolt of suitable size as per thickness of smartphone with/without case.
    * The above combination then be attached to red base with another nut bolt mechanism, this movement needs to be very free and should not produce much resistance.
    * and then instead of using any spring, we can use a simple rubber band between yellow and red parts for the auto-return mechanism.

    ![1|690×342](upload://mvdtCa1Jp4NIAtO9cFVAeAKUN5v.jpeg) ![2|690×395](upload://yDYIQy7Qvpgkylr3alfMDaHytJS.jpeg) ![3|396×500](upload://hcHEwubApW9kaIX7iqQJruSFLN2.jpeg) ![4|690×460](upload://kxYV0oBFRdHzbZcTPiDV46fbL35.jpeg) ![5|665×500](upload://iLE8kpijQrPKreW10zR48UNEt6V.jpeg)

    And here is link to 360degree view of the same: https://bit.ly/2IYlXji

    **.stl** file for the model : [BackTap_MMC.stl|attachment](upload://cvDPJueIrjpQptEhe75D245Zpxs.stl) (195.1 KB)

    I am printing this one now and will see how this one works.

    Let me know if you have any comments for any kind of improvements in design.

    Thanks..!! :blush:

    **Gurbaksh Singh**


    Thank you @Gurbaksh_Singh. It looks good from your images.

    We will test your design and provide additional comments.



    **Hi Milad,**

    Could you please check one important thing first, whether this “Back Tap” functionality works only with a finger tap or it will work with any other material as well ??

    I have checked with one of my friends who is having iPhone with Back Tap functionality.

    But other than a finger tap, he wasn’t able to activate the back tap function. He tried with a pencil, pen and rubber material…but, it didn’t seem working other than finger.

    Please try to check once, and share your experience.


    **Gurbaksh Singh**


    Good point. It uses gyroscope and accelerometer along software to detect back tap.

    So I believe it’s just the way that you push your finger at the back of the phone. Example : move the top part of phone forward and bottom back when you tap the back of the phone. Some AI to detect it on software side.

    I will confirm after testing if it’s true. It might mean that the mechanism would need to simulate that motion. It would be more challenging in that case.

    Thanks for the heads up.



    Hi @Gurbaksh_Singh,

    Sorry for late reply. I have been busy with other projects. I will test it in January and update you.



    Ok Milad,


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