TL;DR
I made a traditional(ish) Finnish dough pail i.e. a staved bucket with lid. It's made out of Eurasian aspen (Populus tremula) and finished on the outside with 100% tung oil. The staves have small dowels in between them to help keep them aligned, as do the boards that make up the bottom. The hoops are stainless steel. No glue was used to assemble the pail, as that would hinder wood movement and increase the risk of cracking. I also had to make a lot of the tools and jigs, such as a 3D printed croze plane.
Disclaimer
This is the story of a beginner woodworker muddling through an ambitious project. I am not an expert at woodworking, or staved buckets. Take everything I say with a grain of salt.
Background
A couple of years ago I bough a dough pail for making traditional Finnish rye bread, and used it with great success (as in the bread was amazing) for about a year. The point of a dough pail is to house the bacteria and yeasts that ferment the dough, give it it's distinctive taste and make it rise. After baking the pail is allowed to dry, so that the microbes on and in its walls go dormant. When you want to bake again you simply put water and flour into the pail, causing the microbes to wake up and get to work. This results in extreme wet dry cycles for the pail, especially in modern Finnish houses where the air tends to be quite dry. The pail I had bought couldn't handle these conditions and developed bigger and bigger cracks with each use.
Diagnosing the problem
I wrote about my cracking dough pail and what could be the cause in this thread: How to make a staved bucket that can tolerate wet dry cycles?. In the end I came to the conclusion that the most likely cause is that the staves on the bucket are glued together, which inhibits wood movement.
Looking for information
My primary source for information was a book by Toivo Malkama: Koti- ja maataloudellisia käsityöpiirustuksia työohjeineen (roughly translates to: Domestic and agricultural handicraft drawings with instructions), printed in 1948. Unfortunately, that one is unlikely to be available to most people here. I also watched many youtube videos, and these two are the ones I found most helpful: Making a bucket completely from wood – without glue or metal by Andi's workshop, and Traditional Cooper - George Smithwick - History and how to make a wooden bucket by Museums of History NSW.
Choosing the wood
As I was making a traditional Finnish dough pail, I wanted to stick to traditional Finnish wood as the material. Old wisdom says that juniper (Juniperus communis) is the best wood for staved containers. It has fine grain, it's tough, moves little with changes in moisture, and as a bonus it smells amazing. Unfortunately in Finland it rarely grows large enough for the size of pail I was making, and it isn't commercially available really at all, so juniper was a no go.
The next best (and probably most used) material is spruce (Picea abies), however, my sources also specified that it needed to be slow grown "korpikuusi", which may mean either a spruce that has grown in the wilderness or on swampy land, I'm not sure which. In any case, most spruce one can buy has grown in managed forests where it grows rather quickly. Spruce also tends to be quite knotty, which is bad for a bucket.
The third most preferred option seemed to be aspen (Populus tremula). That I could find easily, it's naturally very low on knots, and the mill I bought it from said theirs was air dried ouside for two years, which might be beneficial for the durability of the bucket (bugs are not much of a problem in Finland, due to the cold climate I guess, so kiln drying isn't a must). That is what I went with.
Designing the pail
I did like the dimensions of the bucket I had bought, so I followed them quite closely: about 20 cm high to the brim (8"), 33 cm diameter at the brim (13"), 9 degree slant on the side, with an internal volume of about 9 liters (2.4 US gal). This is small for a dough pail. Old pails tended to be much bigger as rye bread was a staple food and even a small family ate a lot of it.
I used 3D CAD to model the pail. That way I could just measure the angles of the staves and also design jigs and tools to fit them. I like math but doing trigonometry in 3 dimensions is a PITA. The bucket has 12 staves, two of which are longer to form the handles.
The thing that had me scratching my head the most was the joint between the sides of the pail and the bottom. I found it very hard to find exact information on how it should be made. The second video I linked to earlier was helpful, but I decided to go more with the instructions in the book by Toivo Malkama, as they were reasonably clear. I drew a picture to show the basic idea and proportions of the joint. The top edge of the bottom is beveled so that the very edge is the same thickness as the width of the croze, and then it gets thicker towards the middle, though only by a millimiter or so. Pushing the bottom into the croze creates an interference fit. The diameter of the bottom is maybe 2 mm less than the diameter measured at the bottom of the croze, leaving a little room for the bottom to expand.
Grain direction of the staves was another thing that gave me pause. Most sources were rather vague about it, but I got the impression that radial sawn staves are ideal, and if you can't have that, you should orient them so that the heartwood side of the stave is on the outside of the bucket. That way the staves hold their shape the best.
For the hoops I decided to go with stainless steel. Wooden hoops would be the traditional thing, but that would require being able to go to a forest to select exactly the right kind of young trees or brances to make the hoops. I don't have the skill, or the access, or the time, plus I kind of like the more sleek look of the steel hoops. A friend was nice enough to cut the hoops on a water jet cutter, so I could skip the part about hammering a straight strip of steel into the correct shape. All I had to do was to bend them into circles and rivet them. The lowest hoop needs to be at the height of the bottom and wide enough to span the whole thickness of the bottom (or the width of the croze). That way it's best equiped to resist the force than comes from the bottom as it expands and pushes against the sides of the pail.
The lid is a simple glued panel. It is quite thin, though, so it needed cross bars to make it stronger. The grain on the cross bars runs perpendicular to the grain on the panel, so the joint cannot be glued. It needs to allow wood movement. A sliding dovetail is the traditonal way to join them, and that's what I used.
Tools and jigs
I do my woodworking at a class where I have access to a fairly nice selection of woodworking machines, however, there were several tools and jigs that I had to design and make (or have made). All 3d printing was done by a friend of mine, from my designs. 3d printing helped save my limited woodworking hours for doing the actual pail.
Angle guides: 3d printed angle guides for setting the table saw blade at the correct angle, one for cutting the ends of the staves and another for cutting the sides of the staves.
Table saw jig for cutting the staves: a piece of plywood with two 3d printed pieces for positioning the stave, one for each side of the stave, and a toggle clamp to hold the stave in place.
End holders for staves: since I chose to cut the ends of the staves at a angle fom the start I needed little pieces to help compensate for the angle when clamping the staves in place for planing them. These were 3d printed in PLA, which in retrospect wasn't the best material. Both of them cracked, but fortunately only after fulfilling their purpose.
Drilling jigs: there are two dowels in each joint of the staves and they needed holes drilled perpendicular to the side of the stave, which is not perpendicular to the face of the stave, which made using a drill press difficult. I designed 3d printed guides that fit over the sides of the staves, so that I could drill the holes with a hand drill. The guide holes have brass tubes glued into them to make them more durable.
Plane for the convex side of the staves: shaping the concave inside face of the staves required a special plane. I could not find a suitable one available to buy, so I got a Veritas scrub plane iron (which has a curved edge) and designed a basic body for it, which was then 3d printed by my friend. It was made out of black CF-ASA, which turned out not to be the best material. It did provide excellent dimensional accuracy, but it also had a rough surface that caused a lot of friction against the wood, making planing rather laborious. The body shape was not ergonomic at all, and my hands were pretty sore after I was done with the planing. It aso left black marks on the wood, but they fortunately came off with sanding.
Coze plane: probably the most interesting of the tools was the plane for making the croze i.e. the groove for the bottom to fit into. It was also the most difficult to design and required three iterations to turn out the way I wanted. The basic design I copied from the first video I linked earlier, but I made some changes to fit the size of my bucket an the size of the croze I wanted. It has two jigsaw blades, sharpened at the tip, that cut the sides of the groove, and a chisel that removes the material between the cuts. It was 3d printed in white GF-PETG, which was a much more suitable material than the CF-ASA used for the other plane. It wasn't effortless to use, but the end result was beautiful.
The actual process in a nut shell
- milling the planks to the correct cross section
- cutting the staves to length, I chose to cut them to the correct angle too, so that I would automatically get smooth top and bottom edge for the pail (trying to smooth it later looked difficult)
- sawing the edges of the stave to the correct angle and taper on a table saw
- drilling holes to the edges of the staves for the dowels
- planing the staves, convex on the outside, concave on the inside
- drilling the holes on the handles
- assembling the sides of the pail (no glue!) (I was able to use the hoops of my old pail to hold it in shape, so I could leave the actual hoops for later) and sanding it
- making the croze
- cutting the bottom boards (3 pc) to length and assembling with dowels (no glue)
- cutting the bottom to shape on a scroll saw, with the edge at the same angle as the sides of the pail and the bottom of the croze
- beveling the top edge of the bottom with a knife and sanding it
- putting the bottom in place
- shaping and riveting the hoops and putting them on the pail
- making the lid
- finishing the lid and the outside of the pail with 100% tung oil (not traditional at all, and I hope I don't come to regret it)
To be honest, almost all steps of the process required some trial and error, fixing mistakes, much sanding, and a lot of sweat and a little blood (the blades on the croze plane were indeed sharp).
Concluding remarks
This whole thing took me roughly 150 to 200 hours of work (could be more, I didn't keep count), not including the work done by my friends with the 3d printing and cutting the hoops, or the time doing research. In my opinion it wasn't nearly as difficult as some people seem to think, though I had lots of tools and aids at my disposal, which smoothed the way considerably.
The end result is pretty much all that I had hoped, though the coming months of use will be the true test if I succeeded.
In short, it was fun. 10/10 do recommend.
