this old post). The lathe bed was long enough, but I wanted to make some improvements to the long 6mm drill.
made a drill for lengthwise boring the first shawm by extending a 300mm auger with some steel rod.
This is the joint formed with some copper shim wrapped around the rod and soldered together. It was strong enough, but required an oversized hole to enter the bore, which defeated quite a bit of the point of being able to make long bores.
With my son Francis working the lathe's treadle again, I lead the drill into the end. The boring started well enough, and the first 300mm was easy enough. After that, things went a bit sour, with the drill seeming to present lots of friction and the shaft getting very warm. I greased it with some candle wax, which made a bit of difference, but by no means not a complete solution.
Also, the drill became more difficult to withdraw to clean out dust, which rather suggested that there was a curve or kink in the bore, somehow.
Since parts of the bore needed opening up anyway, I ran in a 10mm reamer to widen the hole. This reduced the drag on the 6mm rod for a while, but there was still this feeling of a curve or kink. The bore should have been 560mm in length, but I gave up at about 450mm.
I finished the boring with an electric drill and some brute force. Sighting through the bore, there was a definite curve, deviating nearly 6mm from true. Acoustically, I guessed/hoped that this would be tolerable, but the reaming would be interesting.
I tried holding these pieces together in a furniture cramp for gluing, but could not get the two pieces to sit squarely together reliably. I could have made some supporting blocks or something, but this arrangement in the photo was easier to do, mostly. It has the clamping force applied centrally, via the nylon cord running down through the bore to the weight. The force is only about 3kg-wt, but it was enough.
I used a modern polyurethane glue (Gorilla Glue), which is plenty strong enough, with some space filling ability as well.
Let's leave it alone to set and come back in the morning...