For starters hollowing these globes take special tools. These are basically small scrapers. Sorby sells a set of small hollowing tools that has three tools in it one for each shape on the end. One is a straight shaft second is a 45 degree bend and the other is a curved end where the cutter is 90 degrees to the handle. The curve brings the cutting edge around in line with the handle which helps in reducing catches and knowing where the cutting edge is at. Now I made my own tools by taking allen keys reshaping the ends as scrapers and sharpening them.
Another tool you will need is a scroll chuck the way I do them. This is because its easier to hold the pieces once you start.
Wood type for this type of turning isn't all that important at this point. The spindles however I prefer a nice straight grained closed pore wood because of how thin they get turned. I've seen a few of these turned from all kinds of materials. Some were turned from LVL, plywood, various types of woods as well as Banksia pods etc. I really have liked some pieces I turned that had ray flecks one is sycamore that looks really nice turned like this.
These are going to be spindle orientation turnings. I start by turning some stock round between centers and cutting those into what I call ingots of about 3 inches long and 1 3/4 inch diameter to 2 1/2 inch diameter depending on how large you wish. fig 2. If they are larger than your chuck then each ingot needs a tenon to fit your chuck. The 2 inch ingots can be placed in your jaws easily which is why I like to start with a 2 inch or so blank. fig 3
fig 6. I like to drill deep enough where you can part it off later and the hole will come through. I use 5/8 inch but you could do it at other sizes but keep in mind it needs to be large enough to put the end of the hollowing tools through the opening. I like 5/8 inch because I can stick my pinky through and pinch with my thumb to determine thickness.
Once its drilled and sanded I double check that I have sanded the end sufficiently which at this point is mostly burnished to a smooth finish and has a bit of a sheen to it fig 7. In this case I am just using wax because its easy to apply fast and durable enough for as little handling these receive fig 8. Then using a paper towel put pressure on the wax applied with the lathe on to melt the wax fig 9. The friction heats up the wax which melts into the wood and brings up a nice shine fig 10.
At this point its time to start hollowing. I start with the straight shaft to clear some room for the other tools. In the middle scrape till you have a little bulge midway down the hole you drilled. Starting at the rim start scraping out stopping to clear chips and check progress. I use an airbrush compressor with an airbrush but you can use a straw to blow out the chips. You really want this as thin as possible so checking progress often is key. You pinch your pinky and thumb together to get a rough idea how thin. Starting with the rim ensures you wont mess up and creates a starting point for thickness reference fig 11.
This is the part that makes me nervous. You part it off ensuring you are far enough back to still have a rim on the back end. This one I did OK but need to fix the hole on the other side fig 12.
Last step is to turn the piece around. I turn a jam chuck and force the piece on. make sure its not too right or it will split the piece. Finish turning sanding the other side and apply the finish as you did with the other side fig 13.
Coming in part 2 will be the spindles. These resemble icicles coming down from the bottom.