I have some general information on tool selection here at my website, but I’d like to focus more specifically on the adze in this post. It is probably the single most expensive tool used for this work, so it pays to choose wisely. After all, your grandchildren might be using it someday. I only know two adzes well, but they’ve taught me some things about adze design.
I’ll start by showing some photos of the adze I use the majority of the time. The adze head is made by Hans Karlsson in Sweden. The Karlsson’s have a small family forge in Sweden that makes excellent tools. They are designed well, with much consideration for how they will be used. Mine was purchased years ago through Drew Langsner’s online Country Workshops store. It is marked H-161 there. As far as I can tell, it is the same one available from these suppliers based in the U.K.: Woodsmith and Woodland Craft Supplies. They have other adzes there of various sizes made by HK and other good makers.
My HK adze arrived sharp and ready to go (except for the lack of a handle, but that was my choice). It has an outer bevel that is maybe declined eight to ten degrees from the line of the head. A shorter inner bevel strengthens the edge by making the total edge angle around thirty degrees. It enters the wood easily and the weight of the tool propels the edge through. The steel holds an edge under heavy blows, and sharpens easily. All I have done through many sharpening is to maintain it as it came.
My other adze is a good example of how much work will be involved if you buy something poorly designed for bowl carving (even if the product description says “perfect for making bowls”). Before I had any idea what to buy, I purchased this adze made by Pfeil Swiss Made. Their carving gouges are excellent, but they missed the mark on the design of this tool.
The handle is poorly designed in relation to the geometry of the head, and there is no outside bevel at all. It lacks the concentrated weight of the HK that helps propel the edge through the wood. It doesn’t arrive very sharp. In spite of all that, it will indeed remove wood from the hollow of a bowl; I carved some bowls with it. It took lots of tweaking to get it to work better.
After grinding away a lot of steel (carefully avoiding overheating) and adding a new handle, I now have a nice little adze perfect for tight hollows due to a combination of three factors: a tight sweep of the edge, a tight curve along the top of the adze, and a pronounced outer bevel (now). I guess you could say it has a tighter turning radius than the HK, but the HK provides a much smoother ride.
There may be some uses for which an adze with an outer bevel is undesirable. For hollowing bowls, you want some degree of outer bevel. I hope my drawing at the top offers some explanation as to why. Another way to think about it is like this: an adze is like a carving gouge on a stick. When used for carving work, gouges have outer bevels. They provide the carver with the freedom to control the course of the tool and come into, and out of, a hollow.
For bowl carving, outies are the best.
One last thought. If you can’t afford a good adze, but you want to start bowl carving, consider buying a gouge instead. Better to buy a good gouge than a bad adze. You’ll still need that gouge after you save enough for a good adze anyway. You can hog away wood pretty quickly with a large gouge and a mallet. I’d suggest something like a #7 sweep bent gouge (long bent) 25-35 mm wide. It might also be a good option if you don’t feel safe swinging an adze.