Techniques for Successful Boxes

Techniques for Successful Boxes:
Andy Coates looks at the equipment and techniques for making boxes

There are many things about boxes that make them the almost perfect turning project; they can be made from small pieces of stock, even off-cuts, they can be challenging and therefore offer satisfaction when successfully completed, they require thought and planning, encouraging logical progression and attention to detail, they offer virtually limitless scope in terms of design, and they also satisfy that age-old bug-bear of the turned object… they are useful, and as such will always find a happy recipient. Even if they have to pay for it.
For the novice starting out with boxes the best stock to begin with is probably end-grain stock. ‘Square’ blanks, as they tend to be called, are readily available, usually in 75 x 75mm sizes, but branch wood can also be used, even if green. You might also find suitable off-cuts lying around the workshop.
More familiar to most woodturners, face grain blanks can also be used and can provide interesting grain patterns and features, but face grain boxes have a specific associated problem, warping, which requires overcoming in order to achieve a satisfactory fit for the lid. This shouldn’t put you off though; they just require a little careful consideration and maybe a helpful strategy to overcome the potential problems.

Stock choices, challenges and planning
Boxes can be made in any size, but the bigger you go the worse the associated problems are. When teaching box making prepare stock 75mm square and no more than 127mm long. This provides ample material for the mounting, turning, and re-turning of a standard box. All the stock here is suitable for small boxes, and can produce a range of outcomes and designs. If you do not have kiln dried square blanks, but have green wood to hand, then you can still make boxes, but you will need to plan ahead a little.
Choose wood with no visible faults or branches, cut to length and rough turn to a cylinder ensuring you are down to sound wood. Cut tenons at both ends to suit your scroll chuck and mark off the parting point for the lid section (more on this later). If grain alignment is a large part of your ultimate design then it is better to cut through with a fine-toothed saw with the lathe stationary. Otherwise part the two components as usual. Remount the base section and using a Forstner bit, or similar, in a Jacobs chuck, bore out the central wood. On a 70mm cylinder I would use a 30mm bit and assuming a box base of 66mm height I would bore to 40mm deep. Do the same for the top section (adjusting depth of bore) and then tape the two halves together and write the date and wood species on the prepared blank. Put aside for about three to five months and they should be dry enough to re-turn. Preparing end-grain boxes in this fashion has the advantage of providing stable wood at little or no cost, but it does have one disadvantage inasmuch as it restricts the opportunity for dramatic shapes in the final box. If you think you might want a box other than straight-sided or gently shaped, then you would need to take a smaller bore out and hope the resulting rough-out doesn’t crack during drying; having said that, I find that if they are stored in an airy place they rarely fail.
If you have dry stock to begin with you can make them in one session, but even dry stock can (and often will) move once the central wood is removed, so even with dry stock it can sometimes pay to core out and set aside for a few days to allow any movement to occur prior to final shaping and finishing. Experience of the process and wood species will help to make these decisions.
Making boxes from face grain wood comes with the same considerations but also one more that is very important. As face grain wood dries it can warp, or if dry stock is used relax into an ovoid shape across the grain. This can result in a lid that refuses to come off, or if stored apart, refuses to go back on; so it is vital that the fit of the face-grain box is initially slightly looser than that of its end-grain relative. A strategy I often use to overcome this is to cut a recess in the lip of the base section and glue in a pre-prepared dry end-grain ring which can be used as the tenon. You can cut the inner face of the ring flush with the inner wall of the box. The dry end-grain ring will resist the cross-grain warping of the outer material and can be a real boon. It also provides a pleasing contrast and surprise upon opening the box. 

Tools and equipment for box making 
Aside from a basic kit of turning tools (spindle roughing gouge, spindle gouge, parting tools and skew chisel) you will need some other equipment and possibly more specialised tools, although these can be considered as optional.
To ensure all your components are turned to correct dimensions a basic measuring kit ought to include a Vernier calliper, inside and outside callipers, a steel rule and a depth gauge. The outside callipers are invaluable for ensuring parallel surfaces such as on the inside edge of a recess which will house a tenon.
Hollowing the interior of boxes can be achieved with a range of tools including spindle gouges, but often conventional scrapers prove easier to use and result in a better cut, especially on hard end-grain. For face-grain boxes the hollowing is much the same as turning the interior of a conventional bowl, and little difficulty should arise. End-grain boxes present a slightly different experience. Not only is end-grain harder than face grain, but it is possible to cut the wood in the wrong direction if care is not taken – but more on this later.
Specialist hollowing tools can also be used, but due to the small size of the workpiece these need to be mini versions and you may not wish to purchase these initially. A very useful tool is a ‘Box’ tool which is essentially a negative rake scraper with an additional side edge. Proprietary versions are available to buy. My version here [top tool]also has a skewed top edge.

Preparatory steps
Preparing the blank on end-grain boxes is no different than for conventional spindle turning. Bringing the blank to a cylinder with a spindle roughing gouge and finishing with a skew produces the cleanest surface. Tenons should be clean, accurate and turned on each end of the blank.
One important area to consider is proportion. There are general rules you can follow which will result in an aesthetically pleasing box. The general rule is often called ‘The Rule of Thirds’, and this will serve you well, but there are variants you might consider such as 2/5–3/5, where the base is 3/5 of the overall height.
As ever there will always be exceptions to this rule, such as when a particular feature such an especially nice area of grain is to be saved.
Try to maintain as much continuous grain as possible through the top and base, so use the thinnest parting tool (2mm) that you can, or better still part off manually with a fine kerf saw with the lathe stationary. The tenon will take up some material, perhaps 4–5mm, so any saving of wood is an advantage.

The problem of tight curves 
Having cored the base, one of the problems with boxes is the tight radius of the inner curve. With a conventional scraper the bottom left-hand edge is prone to catching the trailing curve when cutting on the centreline. Notice the dust and position of the lower edge in. As the tool is progressed beyond this point the tendency is for the lower edge to push the tool off the cut. It is not uncommon for the turner to tilt the tool up on to the left lower edge to account for this. This results in a loss of control.
A box tool or modified conventional scraper, is ground along the left-hand side edge at about 40–45°, and can also be ground again at the top edge to create a negative rake. The same is done to the front edge. Proprietary versions are available with a rounded leading corner which creates a pleasing interior curve at the intersection of base and wall. This side angle allows the tool to clear the trailing curve as well as producing a clean and stable cut.

Hollowing the box in detail
If you choose to use conventional tools to hollow an end-grain box you may make a common mistake, and cut against the grain. If you pick up a cut in the centre and pivot the gouge to the left, pulling backwards as you cut, you will cut back into end grain and the cut will be rough and cause torn grain on the surface. The only way to avoid this using a spindle gouge is to push the cut forward from the rim to the base of the box. This can be a difficult cut to maintain in a restricted space, and finishing the cut at the boundary of the box wall and base can be a problem.
Probably the most efficient way to hollow is to use a scraper as previously mentioned. The scraper is an efficient tool when sharpened correctly, and ‘scrape’ is something a misnomer. Correctly used the tool cuts.
The modified negative rake tool is less prone to catching than conventional scrapers and may prove helpful if you have struggled in the past.

Handy hint
1. Choose stable timbers such as, cherry, walnut or yew
2. Take special care over sizing components
3. Finish in steps as you progress
4. Finish the tenon and recess last as a tight fit is required to finish the top
5. Always reverse chuck to finish the base to a high standard

Once you have successfully turned the base of a box, you then hollow the top and make a recess for the base tenon and make the fit tight initially so that the outside of the box lid can be finish turned while fitted on the base. Fit can be adjusted as a last stage. Having achieved all this you then need to finish the box to the same high standard.
One of the simplest things you can do to improve a box is to lessen the impact of the join. If the grain match is especially good you may not even wish to take this step, but otherwise it can lift a box substantially. A simple method of achieving this is to make a very shallow parting cut over the join, this is known as a quirk. It masks the join by accentuating the line of the join.
Another method is to turn beads to either side of the join. This does mean that you need to ensure there is enough thickness in the box wall, but if you plan ahead everything will be fine. If you take this approach it is often good to include complementary beads at the top and bottom of the box.
The base is your last area to attend to after abrading, adjusting the lid fit, sealing and finishing. This is why I advise to use a 125mm blank for a 100mm deep box; it leaves you with sufficient waste to turn a jam chuck tenon. Make the fit tight but not so tight it splits the box, and jam the base of the box on to it. Finish the base by cleaning up with light cuts from a spindle gouge and then abrading to a finish.

Conclusion
Boxes are enjoyable objects to make, and the making of one always leads to another; they can be addictive. There are more techniques and skills to acquire than for some other turned objects, but the pay back for the effort is in the joy of making a nice object where you have paid attention to every detail. You can adapt these techniques to make boxes in a wide range of styles, designs and sizes, just remember that anything above 125mm diameter is unlikely to make a good box with a well fitting lid; in the majority of cases the movement in the wood will be severe. Plan you shape, plan the steps, be methodical, keep your eye on the details, and have fun.