Rough Turning and Finishing Bowls. Part 1

For those of you familiar with turning, you will likely be aware of its addictive fun. There is something about creating a usable item from a simple block of wood that give inimitable joy; a transformation wonderful to behold. What’s more, the turner has complete creative control over the entire process – from machining large volumes of wood, down to the minutest line, every detail of the finished product is according to the turner’s choices. This reign of the imagination and range of machining techniques leads to all sorts of inventive creations, making turning one of the most popular forms of woodwork. In this two-part series, Colwin Way will show you how to rough turn on a small scale, and achieve a fine finish with dried blanks.

In this article I will focus on small scale rough turning; although I will also show how to finish off the dried blanks too. I want to approach the subject from the hobby turners’ perspective, and look at techniques that are easily obtainable to a beginner.

What is rough turning?

Rough turning is a process by which a green, or unseasoned piece of wood is turned. By removing the waste wood, the drying time and stresses that can result from movement are reduced. It has found particular application in commercial settings, where saving time by streamlining manufacturing processes is of considerable benefit.

Memories of turning

I have fond memories of rough turning as an apprentice, with shavings mounting up as high as my shoulders around me, and the delight of turning wet wood as it ribbons off the gouge! At that time, we used to process whole trees mainly into salad bowls. That was the scale of the operation in which we worked. The cycle of the seasons was integral to our work calendar. We did most of this work in the autumn, so the bowls could dry during the winter and spring, ready for sale and use in the summer. For larger pieces, this process was really important. The shock of the summer sun would often dry the bowls out too quickly and cause splitting and spoiling of the bowls.

The hobby turner is unlikely to have the ability to process large trees, have access to drying kilns, band or chain mills, along with large scale storage. So imagine this: you’re in the right place at the right time. You’ve driven past a tree surgeon as they pollard cherry trees. Or even better, a friend has heard you’ve got into turning and dumped some logs on your drive. These are typically small logs of timber that you can lift easily and quickly. 

What are the benefits of rough turning?

As previously mentioned, rough turning is the process of part turning a piece when the timber is green, i.e. wet. This encourages a piece of timber to dry more quickly without stress build up and the potential for splitting. In this article we’re looking at bowl blanks. When most people start out in turning, they don’t realise that timber can be turned wet. Nor do they understand which part of the tree a bowl blank comes from, or the processes needed to dry a piece ready for use.

How to dry boards

The general rule for drying planks is 25mm per year plus one year. For example, a board of 75mm thickness will take roughly four years to dry, and a 100mm thick board five years. Boards much thicker than this however won’t really dry out in the core.So, if you want to turn large salad bowls or don’t have storage space, then rough turning is the way forward. There’s also a financial reason for rough turning: wet timber is often very cheap or free compared to seasoned bowl blanks, which can be the most expensive way of buying your timber. I would also argue that the process of turning wet wood is such fun that you will be hooked after your first bowl. 

Hidden hazards

Before we start cutting, splitting and turning, it is important to consider possible hazards that lie within the timber you are working on. This picture (below) shows a stunning piece of brown oak (Quercus robur) which was hiding a fist-sized piece of flint, completely concealed within the timber. The flint only revealed itself when my bandsaw blade began to screech at me in severe pain. It’s not uncommon to find barbed wire, nails, shrapnel or stones that have been enveloped in the tree over the years of growth. Inspect the logs before you start work on them. 

Can I rough turn any timber?

The answer to this question is yes, however, your success with some timbers will be better than others. Ash (Fraxinus excelsior) tends to rough turn extremely well, giving you very few failures. At the other end of the spectrum is eucalyptus (Eucalyptus spp.), which is very difficult to dry successfully. Most of the common timbers like beech (Fagus sylvatica), sweet chestnut (Castanea sativa), ash, sycamore (Acer pseudoplatanus), walnut (Juglans regia), elm (Ulmus spp.), oak and plane (Platanus x hispanica) all dry well. Fruit timbers on the other hand can be a little more unreliable and your failure rate may rise.

Have a plan

The timber I’m using here is from a small oak tree measuring 200mm diameter at its largest point. It’s nice and straight with a striking contrast between the heart and sapwood. It also has a highly figured grain. I like to have some sort of plan as to what I’m going to get out of the pieces I’m about to split. This will largely depend on what you like to turn: natural edge or standard bowl shapes, hollow forms or tall vase shapes. Due to the lovely contrast between the sap and heart wood, I’m going to make sure we have a good selection of natural edge and standard bowls. I’ve marked the end of this log to show you where the two types of bowls come from – the one on the left of the log being a natural edge and, on the right, a standard bowl shape. 

Preparing your blanks

The first approach we’re going to take is the simplest. It is especially good if your log is too big to take to the bandsaw, or if you don’t have a bandsaw. Inspect your log section to see if there are any natural cracks you can follow. Align your axe or wedge to these for the split. It is important that you spread the load when splitting, moving the wedge along the line you want to split. If you don’t do this, you may find that the split veers off to one side. If you’ve ever split a concrete block with a bolster, this is the correct technique to adopt. Once the split has started, chase it down with the wedge to keep it on the right track. A second wedge may be needed to keep things straight. 

In the picture below, you can see the log has been split nicely down its length, showing the two-toned hart and sap wood. It is ready for the bandsaw. If you’re unsure what you want to make, or you’re short of time, this is the first thing to do with all of your logs. At this point, the end grain can be painted with paint or PVA, and the logs left to dry. Halving the logs like this takes away a lot of the stress, and movement is able occur whilst keeping the full width of the tree intact.

Now that the logs are in a manageable state, we can cross cut them to size. We can check the end grain for any splits, and cut it back if required. Measure the width, and cut to the same length using the split flat section on the bandsaw table.

You can clearly see where we can make our bowls from. If making a standard bowl, nature has helped us in providing a natural curve. Turn the piece upside down and you have a wavy natural edge with a white sap and dark hardwood running through the middle. 

Choosing the right blade

The correct blade for the job is very important, and especially so when cutting wet timber. I tend to go for fewer teeth of around 4tpi, which gives more clearance and is less likely to clog with the wet dust and sap. For all the straight cuts in cross cutting and ripping, use a wide blade (in this case 13mm) which helps to keep the cut straight. For curved cuts, such as cutting out your round bowl blanks, my preference is for a narrower blade of around 6mm. You also need to clean the blade and bearings regularly with resin cleaner as you will quickly build a coat of resin and dust. 

Safety warning

Crosscutting logs on a bandsaw or with a chainsaw can be very hazardous and must be done with extreme care. I would not encourage or advise anyone to use a chain saw to do this, unless they have had full training. Crosscutting round log sections on the bandsaw must not be done free hand as the log will spin – potentially taking your fingers or hands into the blade. To crosscut our log section, we’re going to use a large cradle which will prevent the log making any movement. The cradle is made up from a piece of 9mm plywood and several wedges secured with screws.

For extra security, a strap clamp can be added around the cradle and timber. Your hands need to be placed at either end of the log and well out of line of the cutting area. If you are unsure or nervous of this process, go back to splitting with the wedges and do not take any risks.

Crosscutting on the bandsaw

I’ve measured the diameter of the log, and I am cutting a series of billets to the same length. This will give me the option later to process any of the bowl designs mentioned. You can see in the above picture how well the cradle will grip the log. I can also position my hands out of the way. Ensure that the upper guide of your saw is as close as you can get it to the top of the timber: this will give less wander to the blade and cover any unused areas of the blade for safety. I’m using the same 13mm 4tpi blade, helping to keep the cut true and minimising clogging.

Cutting your bowl blanks

Now that the billets have been prepared, we can start cutting out our bowl blanks. I’m firstly going to stand the billet up and cut through the heart of the log. This will help to minimise any splitting radiating out from this point. This gives us two bowl blanks ready for shaping, with a nice flat face to use on the bandsaw. Cutting the bowl blanks into rounds can be difficult with sections of this shape. I use different sized plywood discs to position over the blank. These give a great guide and size to cut to. 

Protecting blanks from splitting

As soon as your wet timber is prepared, it’s a race against time to stop the timber drying out too quickly and splitting. When the blanks are converted for turning, this is a crucial moment and where most blanks can be lost to damage. If you leave the timber for any length of time, make sure it is covered or bagged up – especially if left over night. Better still, you can seal the end grain with paint or PVA.

So far, we have discussed what rough turning is, including its benefits, and how to prepare green wood blanks to make a bowl. This gives us a good foundation to achieve a finely crafted bowl, as demonstrated in part two of this series. The next article will continue with the machining process, including different examples of how to attach the bowl to the lathe at various stages. I will also share my time-proven secrets of how to dry and store your bowl to avoid warping and cracking.

Further reading