3D Printing a Melodica (11) – second attempt
A new material?
After my last attempt warped under the pressure of the springs, I ordered all the parts again, with a few design modifications, in a new material. This time the material of choice was nylon, otherwise known as “Strong and Flexible” at Shapeways. Although very strong, and capable of good accuracy, this was a material I’d rejected previously because if its porosity. But maybe I could seal the essential areas which needed to be airtight? If I could make this work, it would also cost a fraction of the price of the previous Polyjet material.
Is it airtight?
Once all the parts arrived, my first call was to put it all together to see if I had an airtight structure. My old key pad arrangement was letting out air, so I changed the design to simple flat pads, on which I glued soft leather.
Also, my air chamber cover now had extra screws to ensure a tighter fit. Once the reeds were fitted, and the keys attached, I tried blowing into the instrument without pressing any keys. And I was delighted to find that it was completely airtight – nothing could get through.
Now that the basics were all working, I was relieved to finally know that I’d have a good functioning melodica before too long. It was time to seal and paint the melodica. I read that one way of sealing this material is with superglue. This sounded like a potential nightmare to me, especially when trying to get to all the hidden air cavities before the glue starts to dry. Another suggestion was much simpler, and cheaper – Pledge Floor Multi-Surface Finish, or Pledge Klear Multi-surface wax in the UK, which is apparently the same as acrylic varnish. After several coats of this, I applied a couple of coats of Revell acryllic paint, and finished with clear lacquer from the car shop.
I’m still using the same reeds, which I took from a Yamaha P32D, and which I tuned down a tone. I’m looking for an alternative now, as the detuning has left the reeds in a poor state – there’s little chips in the metal, and some of the tongues look quite weak.