quick walk through
Here's a very quick walkthrough...
Assume a flask approx 8†tall by 5†diameter by 2†thick in ash
You will need the above blank, long edges planned and true,
and two pieces of softwood, for use as sacrificial wood, 8†by 1 1/2†wide by 2†deep, with planned long edges (8*2 side), and a blank ½ thick, or thicker and turn it down, by 4†diameter
glue these three pieces up to make a square blank 8†by 8†and allow to cure properly.
Mark the centre of the large flat sides, and the centres of the two ends.
Mount between centres so that the three pieces are horizontal in relation to the lathe bed, drill down what will be the neck into what will become the body of the bottle using the jacobs chuck and a suitable (10-15mm) twist drill of sawtooth bit, to the depth of the bottle. Using a revolving centre in this hole turn the shape of the bottle, remembering that the shape must be fully of ash and not sacrificial softwood. This is only there to stop tearout at the transitions between neck and body of the bottle, and on the sharp edges between what will become the sides and front of the bottle.At this point you can turn a spigot on the headstock end of the blank. This will be an incomplete circle but should be enough to hold the bank to shape and complete the neck of the bottle. You can do this before the next step.
This done, you need to mount the remaining wood on a screw chuck, making a very accurate centre mark to drill into, on the large flat side (front or back of the bottle). Mount and cut a recess, say 2 1/2†- 3â€Â, but of a size suitable to be be held by a scroll chuck in expansion mode later on, and then turn out the inside, without damaging the recess. You will need to undercut into the body of bottle. You will meet up with the drilled hole.
Remount using the recess as your chucking point and turn a circular pattern on the back of the bottle.
Mount the 4†blank on the screw chuck, glue chuck, or jam chuck and turn a disc to fit the recess you cut, make the pattern on it match the circular pattern you turned into the back of the bottle. This disc is then glued into the recess to seal the bottle.
Remount between centres and remove the spigot.
Remove any remaining sacrificial wood, on a belt sander, hand finish, turn a stopper for the bottle and you're done!
I hope you get the idea from this short walk through!
Andy