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There are two basic ranges of straight (i.e. unbent) gouge sweeps and from those there are derivatives that are curved in various ways to assist access for difficult cuts.
The English pattern (often referred to as the Sheffield list) is one that was adopted by the English tool makers from the 19th C when the sweeps began to be standardised in shape and the Continental pattern which looks the same but has a slight difference in the numbering system. Basically in the English pattern, gouges are arcs of a circle ranging from a No: 3 to a No: 11, which is a semi circle. They are then graduated according to width.
A 1" No 11 is a 1" semi circle, while a 1" No 3 is an arc of a far larger circle. A table of comparative arc sizes is essential and makes it appear quite easy once you are accustomed to it.
The trick with carving is to select the sweep of the gouge that matches your cut exactly and to keep them all in razor condition so the finishing cut is straight from the tool and to use as few tools as possible - it's quite remarkable what can be achieved with just a few straight basic gouges.
(No 1 is a straight chisel, but bevelled on both sides. No 2 is a straight skew. The differences in sweeps are academic and you can find that out from a good book).
Vee gouges are tricky to sharpen, but you will benefit from a 60 and 45 degree vee to start.
Used tools in the UK will almost invariably be the Sheffield pattern and can be an excellent source of quality kit.
I would recommend a good book as a starter before you even consider buying tools, because it is far more economical to buy the tools as you need them and fettle them for use one at a time than to go in for extensive sets devised by a manufacturer that look good on the wall and mostly remain unused.
I'd recommend sticking with one pattern or the other. Mixing sweeps can be confusing.
I don't have a vested interest, but one of the best teachers around is Chris Pye.
Two excellent books on introductory basics are:
http://www.chrispye-woodcarving.com/wri ... 1vol1.html
http://www.chrispye-woodcarving.com/wri ... 1vol2.html
Volume 1 deals with tools and sharpening in some detail.
His main site is here with a lot of good stuff that can be downloaded free.
http://www.chrispye-woodcarving.com/
Worth a look - he's one of the top carvers around in my view.
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