First Shawm - Boring Breakthrough

From my first boring attempt, it was more than obvious that keeping the drill well aligned was the thing.

Another thing was to reduce the cutting rate of the auger so that the workpiece could spin more and help keep the alignment good. To allow this, I ground off the auger's leadscrew to a flat end, and then relieved the cutting edges enough with a file. This meant that the auger would not drag itself in willy-nilly but would have to be pushed, giving more control.

The other major innovation was to get someone else pedalling the lathe, leaving me free to concentrate on managing the drill's progress. Acknowledgements to my son Francis for this.

Here's the improved drill guide fastened properly to the right hand end of the lathe.

Here's a view looking through the hole in the drill guide. You can see the rear (concave) face of the hollow centre and through that, the driven centre at the other end of the lathe bed, all nicely lined up.

Here's the new workpiece mounted in the lathe.  I didn't bother to cut it down to square, since I didn't know how much wander there would be. At the right of the picture, you can see the extension to the 6mm auger passing through the drill guide, showing that drilling is already well advanced.

Another view of the drill and drill guide.  Note the fender washer clamped to the drill guide, which provided a fine adjustment for the alignment of the drill.

Another view looking along the drill shaft extension as it disappears into the workpiece. Initially, I ran the 6mm drill in until it couldn't go any further because of the brass jointing sleeve. Then I ran in the 10mm spade bit following the 6mm hole as a guide.  I wasn't sure how centred this would be on the 6mm hole, but it didn't greatly matter at this stage since all this part would be reamed out anyway.  As it happened, it did stay fairly well centred. Having widened the hole far enough in, I put the 6mm drill back in and bored through until it should have been about 10mm from the end.

I drilled a sighting hole crosswise at the driven end of the workpiece, and  there was the borehole, a total of about 6mm off centre. For a 440mm lengthwise bore, this seemed pretty good to me.