December 23, 2012

S3 prototype construction - part 3

This is what happens when it falls on the floor! A "not happy Jan" moment! Turns out it was a lesson worth learning. This was put together with PVA glue and screws - I later removed the screws. The impact of a fall from the bench had it all fall apart immediately. The glue had set, but clearly there was not enough strength to stay together. 

For now I'll build just one and test.

Brackets were made to attach the mouth flare.

Attaching the mouth flare. Brackets hold each piece in place. Previously I assembled these with the mouth face down, but this method lines up the pieces at the knee much better.

Now assembled:

I used polyurethane glue for the mouth flare. It's a bit of a pest to work with and takes longer to set, but has four times the strength and expands to fill any voids. As such, it's much better at fitting together panels that aren't perfect. It takes much longer to achieve perfect and on a prototype, I certainly don't think it's worth the extra time.

The ooze on the glue is a good sign - it means no voids. I used construction adhesive on S2 and it wasn't reliable enough.

Remember, this is a prototype! It can be dressed up later if desired, but speed is the important thing. It's all about testing the design and moving on to the final version ASAP!

In seeing all this, you may start to realise that building a point source horn is quite difficult! Even for an experienced wood worker.

Coming up:
  1. Work on ports
  2. Throat profile needs to be filed out
  3. Smoothing the horn profile overall
  4. Trimming the mouth
  5. Driver mounting
  6. Stand
  7. Testing and evaluation!

1 comment:

All comments are moderated.