Re: scooping chair seats
ThomD
>If we are talking aobut windsors, where they aren't saddled all that deep, and the woods of choice are softwoods, then handtools are really efficient, it takes maybe half an hour, by hand. Probably that can be done a lot faster. You start with a guttering adze, then move on to an inshave, then a plane or travisher. http://countryworkshops.org/store.html sells everything you need. I use their hollowing adze, rather than the windsor one. I like CW because they sell a lot of the tools unhandled at significant savings.
If you are looking at more modern chairs with say maple board seats, like Maloof and such, then you may need to consider the heavier techniques like chainsaw, lancelot type tools, and grinders. There is a lot of art to grinding, and it is very fast with agressive tools. More woodworkers probably own chainsaws than own hollowing adzes. Both tools require a lot of skill because they have pretty unlimited cutting geometry.
If your chairs are made out of multiple boards,you can waste a lot of material on the bandsaw prior to glueing. And another technique uses splines to force curvature into the seat blank.
Whatever you do, don't do like some instrument makers I know who carve jazz guitars out of hard maple using tiny violin planes. Get the big chips flying at first, it is much faster, your carpal tunnels will thank you, and accuracy is not affected.