I am looking to carve a tapered recess into a piece of wood, like that of the center element in the picture below:
What is the best way to do this?
The short answer is: there are tools designed for that. Here are just two random examples:
The long answer is that tools alone aren't enough to produce this result. You also need the skill to use them. In modern times machines like CNC routers can help with shaping precise forms, but you also need the skill (knowledge) and tools (router bits) for them.
Depending on how big the wood is you might be able to use some lino-cut tools or wood chisels to get a similar shape especially if you just want the middle part. This would work best on a softer wood like pine.
Basically cut the overall piece how you want it. Then mark and carve out the general inside shape and then go back in with a LOT of sanding paper getting finer and finer until it’s smooth enough to finish with a varnish if you want to finish it at all.
The piece looks like it was made from a single piece. The typical approach for this would be to turn it from a longer piece in a chuck, or on a face place, without centres and use a boring bar to cut out the interior of the material before slitting it into the three pieces.
To reduce the amount of material, it is possible to use a curved trepanning tool to cut out hemispheres from the material in turn to avoid having to turn the entire interior out.
The last pass would need to be pure boring work as the interior is a pointed, not a spherical shape.
I have never tried it, but wood burning with a laser is possible, or using a square wood chisel to cut nearly straight lines.
We begin with a rectanguilair prism or rectangulair piece of wood.
On the first pass, the laser burns a 1/8 inch wide black colored line into the wood or a 1/8 inch wide steel square tipped chisel carves a shallow groove 1/4 inch wide.
The second laser pass can be divided into three sub-paths (2.1, 2.2, 2.3)
On path 2.2, the laser re-traces the original blackened line, making the original laser etching deeper after pass 2 than the etching was on pass 1.0
Laser passes 2.1 and 2.3 makes two new lines which were no etched during pass 1.0.
The lines, or curves, run side by side.
Before anything is done (on iteration zero), the entire wood surface is flat (depth zero).
Between iteration 1 and iteration 2, there exists an etching path of depth 1 which is 1/4 inch wide. There is one shallow valley or groove in the wood.
Between iteration 2 and iteration 3, there exists an etching path of depth 1 which is 3/4 inch wide and there existing an etching path of depth 2 which is 1/4 inch wide. In other words we have three grooves, 2 of which are shallow and 1 of which is deep. The two shallow grooves parallel the deep groove. The deep groove has been cut twice. The two shallow grooves have only been cut once.
A cross section of the wood piece would look like a minature step pyramid or south american meso-American pyramid, where the ayramid I made of air or the step pyramid is the absence of the wood.