How can I drill the underside of a chair so the spindle legs come out at an angle, making the chair more stable?
(Furniture Making Forum)
From contributor R:
It depends on if you are going to do a dozen chairs or hundreds. For a few, you need to figure out the angles (usually compound) and you can drill a simple block with a hole the right size through it. It takes some time and setup to get the proper hole angle in the block, but using a decent drill press, it is very doable. Then simply clamp the block to the chair bottom and drill using the angled hole in the block to guide your drill bit.
For hundreds of chairs, there are machines available to do this, but I'm guessing you are not looking in that direction.
We built 120 chairs per day for many years. What we used for leg screws was to lay a drill down at a fairly low angle, and drill a 3/16" hole in each leg. Do this from inside the leg area, harder to do but less visible. Then put an inch and five eighths wood screw in each leg.
That and the glue will hold the legs in just fine. I still have a set of those chairs, going on twenty years and they are still holding up great.