Multi-axis, or 'eccentric' wood turning is the turning of parts in two or more phases, set at different axis. The different axis can be parallel, angular, or at 90 degrees. In most cases, this will mean turning a piece of wood in a very lopsided way, with the center of gravity offset from the axis. I recommend using a robust lathe for this purpose, along with a faceplate when possible, though I have seen more extreme turnings on lighter lathes than the one I am using here.
In this project you will be making a traditional rustic Romanian-style canteen/flask/jug. This one was made at TechShop.
You will need:
-A sturdy lathe with a faceplate
-A large drill bit (around 1") and a way to turn it
-A turning gouge chisel
- A straight turning chisel
-Wood finish (optional)
Step 1: Axis 1
The first step is the standard woodturning process. If you can, drill the mouth of the bottle first and use it to set the centers. This will ensure you are starting with a concentric shape with the mouth in the exact center. I am using a scrap of 6"x6" Douglas fir; I do not typically recommend using soft wood for multi-axis work (note the chucking around the rim), but this is just a demonstration and probably a good option for your first such project. The first turning must be finished smooth at this step. Sand and do whatever else to finish this surface, you will not be re-mounting it again.
Step 2: Cutting Off the Shanks
The easy part is over. The piece must now be re-mounted to bowl-out the interior from one side. I used a bandsaw to cut-off pieces from two sides, giving a flat mounting surface for the faceplate. Save those two shanks of wood, you will be using at least one of them to cap the big hole you will now bore in the side of the jug.
Step 3: Bowling-out the Interior
This step is essentially bowl-turning, except you will be turning an asymmetrical piece that will remain asymmetrical. If your lathe has speed control, ease into it. I find I can safely rough-cut a piece like this at 700rpm. Your chisel will want to wander away from the center, so make your cuts carefully and perpendicular to the surface you're cutting into. Start from the perimeter and move in towards the center, resisting the outward force. If you drilled the mouth deep enough, you should break-through to it. When working with hard wood, you can leave much thinner walls than I did here. If you have the skill and a proper square chisel, make a step in the rim of the bowl to better seat the cap later on.
Step 4: Decorative
This next step is more decorative than anything else, though it will add some balance to the piece and all visible surfaces will have been turned. The jug must be turned around so you can work the other side. You can screw the faceplate to the inside wall of the jug, but only if it is thick enough that the screws don't hit your chisel as it digs into the piece. A better option is to forgo the faceplate and use both centers.
Step 5: Turning the Cap
Remember those shanks you cut off in Step 2? You will only be using one, preferably the one from the side that was hollowed. Glue it to a block of wood and mount it on the faceplate. Only turn it enough to make it perfectly round, and give it a lip to better seat inside the hollowed bowl of the jug. Use calipers to get the measurements precise. If you have threading tools, this would be a good opportunity to use them, though threads may make it difficult to get the grain direction to match. Cut the cap off the block. The sawn surface doesn't need to look nice since it will be on the inside of the jug, just give it a quick sanding.
Step 6: Finish It
Glue the side cap in place. If you want to make this a functional canteen, use a food-safe finish like pure tung oil on the inside and outside. There are other enert and/or harmless finishes available, though they don't have the lastability and moisture resistance you would want for the inside of a liquid vessel. If you're fancy, turn a wooden stopper and knobs for attaching a shoulder strap.