Archive for April, 2006

Lidded Boxes

Tuesday, April 11th, 2006

Tonight a very entertaining Brad Hubert introduced us to the art of box turning at the monthly MWA meeting. Brad has several hundred boxes under his belt. It was interesting to see the different approach of a production turner.

Wood choices

Brad makes all his boxes from wood ‘harvested’ in his neighborhood. Most native woods can be turned and also turned into lidded boxes. He starts out rough turning long sections of green wood. Once round, he uses a bandsaw to cut them to the desired lengths for the lids and bottoms, careful to keep the pairs together for best grain alignment. Sometimes he then also ‘rough hollows’ the pieces to relief stress and accelerate drying, then he puts them aside for several months for drying.

My wood pieces are typically smaller and only big enough for a single box. I start between centers, turn the wood round, add a rebate to both ends for later chucking , and cut the top and bottom appart with a saw or a thing parting tool. Brad rounds over a long section of wood and cuts it on the bandsaw. He also foregoes the rebates on the lids and just chucks in the entire top, which saves material if you have a big enough chuck.

Inside: the top…

The top usually being not that deep he just uses a scraper to quickly hollow it out. Then he uses a special side-ground scraper to cut the rebate into the lid that will later fit over the bottom. He adds a very light chamfer to the inner edge. At that point the inside part of the lid is done. Brad does not sand them, he says with sharp tools and sufficient practice the finish obtainable by a scraper is fine enough to leave.

…and the bottom

The he chucks in the bottom. He starts hollowing by making a small dimple into the center, then he uses a long drill epoxied into a handle to drill out the center. He has permanently marked the drill in inch increments (I meant to ask how, seemed like he turned in thin lines on a metal lathe. I have to ask him next time I see him). These markings help him to gauge the desired depth (Brad reminded us several times that the inside of a box MUST be smaller than the outside…). Then it is back to gouge and scraper to hollow out the bottom.

Brad briefly mentioned the back hollowing method, a method to very quickly hollow out wood which amongst others is featured on the (scary) Richard Raffan videos. It is hard to master, and being so quick it is very easy to go to far…

Next Brad uses a peeling cut with a skew to cut the rebate onto which the lid will fit. Here patience is important. By repeatedly cutting, stopping the lathe and test-fitting the lid the correct size is found. As little as 1/1000th of an inch is the difference between a snug and a loose fit. At least for now I prefer a snug fit (it can always be loosened up later), that makes turning the outside of the lid easier. But if it does get too loose a couple sheets of toilet paper help here. Even Brad with his box turning experience needed several attempts. I was relieved to see that he stops the lathe for test fits, unlike a practice shown on some professional turning videos. A trick to use here is to cut the rebate with a very slight bevel. Once the lid starts to fit over the rebate the rebate is carefully squared up.

The outside

At this point the inside of the box is done. The lid is attached. Brad additionally secures it with a strip of masking tape (a very good idea!). He turns the top of the lid to the desired shape, then works his way down the side and in the process the masking tape is turned away. While working on the top light cuts are essential, any catch will most likely send the lid flying.

We do that by magic…

At this point the box is finished. Or ist it? Brad kind if glossed over the detail of turning the bottom of the bottom part and removing the rebate used for chucking. We do that by magic he says… That was a little disappointing as that part gives many beginners pause. But he did explain the basics briefly: One starts by chucking up a piece of scrap wood. A rebate is cut into it, into which the top of the bottom will fit snugly. As before, patience is the key to get the size just right. The bottom is fit into it, then it can be turned. The problem here is that the bottom can’t easily be secured with masking tape like the lid, and also that the bottom is typically deeper than the top, so there is more lever action while turning. I typically use the dead center to help support the work as long as possible, and by making very light cuts.

Finishing

As with most wood projects many kinds of finishes can be used for wooden boxes. Brad prefers Danish Oil which he applies off the lathe in two or three coats. Danish Oil is very easy to work with and almost fool proof.

Smaller boxes are often used for jewellery, so Brad using flocking materials to finish the insides of such boxes.