3D Printed Flexure MIDI Keyboard update

As this project is nearing completion, I can show off the different features and changes I have made in this revision. The change from photoresistors to phototransitors solved a lot of problems and now the velocity sensitivity is finally working as intended. The compliant mechanism is also working perfectly. There are still some tweaks before building the full version but we're getting there.

[@ezion67]

I love how the flexture mechanism moves the pivot point of the keys. Years ago I made a organ pedal keyboard that used opto interrupters. Assuming you use a key scan method, you only need to light up one LED at a time. By using shutters that have 3 light levels: dark, half open, full open. You can easily implement key velocity. Just use a comparator circuit to convert the output of the foto transistors in a 2 bit signal. Have fun and good luck with your project.

[@Metalrasputian]

This is so cool! If you do go the PCB route, you could design a motherboard with po-go pins and then have each key use the same PCB design and have contact pads on the underside, making a modular key setup. You'd just need to update the 3D model of each key module to position the identical boards. Also, to solve the power draw issue, you could look at using hall effect sensors and embed magnets into the keys. Or vice-versa.

[@kruszielski]

What a great project! Make it modular and you will have one of the best midi controllers possible!

[@travismason2811]

I've kind of wanted to start playing around with thin film pressure sensors for computer keyboards, and testing it as a sound input device would be interesting too.

[@DJthefirst]

Hi, Im also going as a presentor at opensauce for my self playing midi instruments. See you there!

[@heckintech]

This, is FASCINATING, and I want one! 😍

[@zubrkabbi]

OMG thanks for the wintergatan melody and music box thingy! I love the style of your project updates, will be waiting for final build

[@patriciosalvatierra953]

capo chabon! buen video

[@marcustx]

I would be happy to help with: power consumption, and PCB design -

[@sombranegra335]

Hey, I have also tinkered with some pi Picos on trying to do that. At first, I thought about a button matrix, but it wouldn't be velocity sensitive. Then, I saw a video online that tried to do that with hall effect sensors, but it was a bit expensive. Yours is a pretty cool and well built design, but, I still have a question, couldn't you have just used soft buttons instead of all that optical madness? There could be 2 buttons replacing the two phototransistors. I took this idea from a cross-section model I saw recently on my music centre of a thorman digital piano. I took a video about how it worked if you want it. I would love to share with you some of my ideas to try to make it as cheap, reliable and efficient as possible.

[@elterla2153]

soft buttons would be great for a mass produced product but aren't very DIY friendly as far as I know. The alternatives I've found with other buttons tend to be a bit noisy whereas the phototransistors are completely silent. The solution I'm currently using does involve a matrix but doesn't sacrifice the velocity sensitivity because of it. Hall effect sensors are a great option but a bit pricey and I suspect they are more computationally hungry when calculating velocity. At least this had been my reasoning

[@sombranegra335]

@@elterla2153 are you planning on adding speakers to the keyboard itself to remove the necessity of being connected to a pc? With an SD card slot for different samples, idk.

[@elterla2153]

not really, I always intended this to be a midi controller but once I release the files someone else could go that route

[@stkarthikeyan4318]

This is fascinating can i have a see on your source code