Saturday, December 26, 2009

First Shawm - Prepare to be Bored


One the interesting/exciting/challenging things about making woodwinds is drilling the lengthwise bore. In this design, this involves drilling a 6mm hole down the length of a 500mm piece of wood, and staying reasonably central.

This drilling really has to be done on a lathe, and to do this, the lathe needs to have a hollow centre to hold the end of the wood, leaving the centre free where the drill enters it.  My lathe, being somewhat hand-built (to be described in a later post), did not have a hollow centre.  So I made one for it.




Out of my "old plumbing" collection, I took a pressure reducing valve and used one of the brass bell housings from this.  This had a nice flat face with three nice mounting holes and a nice cylindrical section which polished up nicely (am I painting a picture here?).  Mounted on a wooden tailstock cut to fit the lathe's bed, it fit the bill very well.



The position of the brass bell housing on the tailstock required some adjustment to make it centred on the existing driven and fixed centres.

I moved all the centres together as shown in this picture.  On the left is the driven centre, and on the right is the hollow centre, and you can just see the point of the fixed centre showing through.

The hollow centre has already been adjusted, by eye, and this was a final check.



This is a view looking back the other way from the picture above.

The fixed centre is in the foreground, pointing through the hollow centre to the tip of the driven centre in the background.



This piece of wood is being prepared to fit into the hollow centre.  The right hand end has been turned down to a snug fit inside the hollow centre.



And here it is, now fitted in place.

This picture shows boring fairly well advanced, and evidenced by the drill shaft extension passing into the hollow centre at the right.

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