We were treated to a confident presentation from Mark as might have been expected from someone with his background as editor of Woodturning and ex product manager of Sorby as well as being an experienced turner in his own right.
The first item was a box mounted in a curved stand. He started with the top of the stand, being a rectangular block of ash mounted sideways.
The turning involved a lot of “air cutting” as the most of the wood surface made only intermittent contact with the tool. This called for firm tool control with the rest as close as possible. Mark sees nothing wrong with scraping with the edge trailing provided the scraper is kept sharp. Honing rather than grinding is advocated for sharpness and tool life. Having shaped the top side including a recess for the chuck, the stand was reversed and the underside shaped in a similar fashion, breaking through the centre to leave a hole to accept the box.
Mark approves of colouring if the wood is suitable and ash is such a wood with sufficient grain to still look like wood after colouring. In this case he used an ebonising spray.
Whilst drying, Mark turned the box from cherry. The technique was fairly conventional but a few tips emerged. For instance, Mark generally rough-turns boxes and leaves them to relax before finishing. This is recommended even if the wood is dry because movement can occur as the inbuilt stress is altered by hollowing. When reversing, if the box is to be held on the chuck jaws at the rim, a sheet of tissue can be used to prevent damage.
The lid was finished with a finial. The temptation to make this too fine should be resisted as it is the obvious part to grip when taking the lid off and prone to breaking if too slender. On the perennial subject of lid fit, for most purposes, when the lid is lifted, the box should stay put.
Mark did not do as much sanding as he would have at home because of dust. He takes extreme precautions to protect himself from dust having developed sensitivity from exposure early in his career.
The second demo was a wavy edge square bowl. Mark claimed no originality for this, the idea being ancient but he gave Terry Scott credit for recent refinement. Again the cutting involved non-continuous contact. The tips were left thick and shaped with the lathe stationary, alternately up and down.
The shaping could be done with a saw and sanding but a mini Arbortech is much quicker. Mark did not finish the bowl but you can see the idea from the pictures. How about some at the next gallery?
And for a quick finale, Mark turned a cylinder with radial cuts with a parting tool to various depths. This gave the appearance of a hidden vase when viewed side on. Spraying black enhanced this. The top was fished with a thick blob of copper loaded paint which he blistered using a blowlamp to give a copper textured finish. A quick and unusual piece of work.
Finally Mark gave a helpful critique to the work on display in the members gallery. It is good to see another impressive display.
Those of you who have followed the gallery recently will have noticed Mike’s lovely bowls with rims inlaid with contrasting wood patterns. There had been so many questions about how it was done that Mike agreed to show us by way of an evening demonstration.
Mike had already prepared an inl
ay with alternating contrasting wood segments glued with PVA onto an MDF disc about the same diameter as the bowl. The disc had been marked out into 24 equal segments using the indexing facility on the lathe. Wooden segments about 8 mm thick were cut on a bandsaw, and the edges of each sanded precisely to fit the adjacent segments without gaps.
Mike prepared the bowl by mounting on a chuck via spigots. We wondered why Mike went to the
trouble of turning a cylinder rather than shaping the outside of the bowl straight away. He proceeded to part off a ring from what would have been waste shavings for use as a future inlay. Aah! Apart from this removal he left the outside of the bowl to be finished later so that it would be as rigid as possible for fitting the inlay.
He had made a useful jig to fit the tailstock with 2 adjustable needles for marking the bowl rim for a groove to take the inlay and also for marking the inlay itself.
First the inlay was cut in the form of a ring
, the MDF being retained to support the segments. Mike incorporates a very small taper to fit the groove snugly.
With the bowl mounted with the base in the chuck, the centre hollow was started, leaving a spigot for re-mounting, and the rim marked for grooving using the tool without changing the inlay set up. The groove was cut carefully to a depth of about 3 mm and after a few trial fittings, PVA glue was spread on both faces and the ring pressed into position and clamped.
(Whilst waiting for the glue for a few minutes, Mike gave the gallery critique.)
Finally the bowl was remounted and the MDF ring and surplus inlay was turned away and the rim sanded.
Mike left the remaining bowl turning to be done in the usual way for later but had brought several very nice examples of finished bowls.
The gallery contained a good variety of work which can be seen on the website. Mike said he felt some embarrassment at having to comment on the work of other turners being a relative newcomer to the craft. But I think his work belies his inexperience and well qualifies him to perform the critique.
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The December meeting is traditionally a social affair and once again we had a quiz with questions including both turning related and other questions.
Attendance was higher than usual and members formed themselves into 6 teams with imaginative names to do battle.
Questions were prepared by various committee members Quizmaster Jon Gibbs posed these in 8 rounds on Sport, Picture identification, Current Affairs, Scrambled Sayings, Cryptic Turning Phrases, General Knowledge, Wood and Turning Trivia and Geography.
Teams could nominate a round in advance to play their jokers to double the score of that round. No team optimised this choice which could have altered the result entirely.
In technically advanced fashion, the scores were kept on a laptop spread sheet by Alan Sturgess and projected onto a screen. The initial front-runners, the Magnificent Seven were pipped at the post by Ron’s Ravers with Tweedle Dum and the Tea boys coming a creditable third. The winning team were awarded prizes of sweeties and the wooden spoon went to the Novices.
In the interval tea was served supplemented by supper of chips and mince pies.
It hadn’t been made clear whether there would be a gallery but 4 members were keen enough to bring something along ranging from miniature bowls by Jean Turner to a large oak bowl by Jon Gibbs. All the pictures are on the website.
The evening was rounded off by calling the raffle which had a large number of seasonal prizes.
Offered the choice of a box or a bowl by Les, the members asked for a box. In fact Les did both, starting with a box in ash. I’m not going to describe the demo in detail; anyone interested can get a DVD from Les. What you don’t get on the DVD is the famous banter and interplay with the audience. There were useful tips along the way with pros and cons of, for example, push and pull strokes in hollowing. The use of a lacquer to seal the ends of the fibres inside the box before making a final cut may also be new to some. Sanding sealer can be used as an alternative but Les prefers spray lacquer as less messy and more uniform. Les’s view on the perennial debate about the fit of the lid is that it should be neither too tight nor too loose. Ideally picking up by the lid should leave the box on the table but if inverted, when picking up by the base, the lid should stay attached. A fine balance! The fit should be tight initially to allow the lid to be jammed on for turning and then the relieved slightly when the lid is finished before reversing the base.
The box was attractively shaped like a bottle kiln with a bead at the top to provide a finger grip to remove the lid. The open grain of ash lends itself to being picked out by a coloured filler. Les first sprayed with an ebonising lacquer to give a shiny black base and, when dry, rubbed in Liberon gold coloured filler. The excess was wiped away using wax which was buffed up to give a nice finish.
Les went on to turn a natural edge bowl from a half log with grain at right angles to the axis of turning. No time to finish it, but Les left that to a volunteer from the audience. Hopefully we’ll see it on the gallery table next time.
The evening was rounded off by a critique on the gallery which was impressive in terms of both quality and quantity. It would be nice to see this effort maintained.
We had a great turn-in this month, loads of great work on display
Every woodturner uses wood but many have only a vague idea of where it comes from and why it can be so unstable. This evening’s presentation by club members Bob Hope, Alan Sturgess and Dave Gibbard shed some light on the subject.
Bob described how trees take in their nutrients dissolved in water via their roots by osmosis and how this passes up the trunk in the sapwood. So wood contains water, which, as a % of the dry weight, is called the moisture content. For a living tree the m.c. can be over 100% (i.e. more than half the total weight). Once a log is cut it will lose water and eventually reach equilibrium with the atmosphere. Even in a “dry” house, at the equilibrium point the wood will still have a m.c. of about 12%. In a damper atmosphere and it will re-absorb water and will reach a higher m.c.
Wood is composed of cells. Free water between the cells is lost quite quickly but that contained in the cells takes longer.
The problem is that wood shrinks as it dries and the shrinkage is not uniform. Shrinkage along the log is negligible but radially it is typically 4% and circumferentially it can be 8%. This means if you leave a log to dry the stresses build up and it will surely split.
There are several ways of dealing with this:-
Cutting
Alan showed the various cuts a sawmill could make to allow the cut wood to dry without splitting. The cheapest option is to cut “through and through” into parallel planks. However, depending on the position in the log, some distortion will occur, producing what some wag in the audience described as B&Q planks. A better method is to “quarter saw” so that the grain is mostly through the planks. However this is laborious as the log has to be turned 90o for each cut and is wasteful of timber.
Water replacement
The water in the wood can be slowly replaced by PEG (poly ethylene glycol). This is how the recovered timbers of the Mary Rose were treated to stabilise them. In that case spraying took several years but small items can be immersed in hot PEG solutions and the process can be reduced to a month or two. Few of us have experience of this process and it is not widely used by turners because of the complexity. It can also change the appearance and texture of the wood.
Rough Turn
Dave showed some bowls that had been rough turned when wet and allowed to dry. Most of the wet wood is removed to give a rough bowl shape with a wall thickness roughly proportional to the bowl diameter (say 1” per 10”). This will dry much more quickly than a thick disc blank and is the only practical way of making a deep bowl. The drying process is often slowed down by sealing the exposed surfaces. This allows the wood to accommodate the stresses produced by drying. Sealing can be done by dipping in molten wax, painting with PVA or wrapping in paper or cling film.
After drying the rough bowl will have distorted and is re-mounted on the lathe and turned to its final form.
Wet Turning
An alternative to drying before turning is to turn wet. It is necessary to turn to a thin wall to allow the wood to dry quickly without splitting. Some distortion will occur. Decorative items, often with the bark retained, can be very attractive when produced in this way. progression from cut log to finished item can be as short as a day or two. Dave showed several examples turned with grain parallel with the turning axis and at right angles to it.
After tea, Bob and Alan demonstrated the process of cutting a log and rough turning it.
Normally the cutting would be done with a chain saw but for the demo a safer but slower reciprocating saw was used. A cylinder was cut and split to produce 2 “D” section pieces. The corners were cut off to reduce the subsequent tuning and the work piece was mounted on the lathe with the flat face of the D facing the head-stock. It was turned to a rough bowl shape with a spigot on the bottom. Reversing to mount the spigot in a chuck, the centre was hollowed out. As an unintended part of the demonstration, the spigot split off and had to be re-turned. This was because the spigot was cut from a very soft part of the log near the surface. It is a good idea to sacrifice a little more wood to ensure the spigot is from harder material.
After all that excitement Jean Turner gave a critique of the gallery items.
It was good to see a new face, especially that rare phenomenon of a female one in this role and to hear some thoughtful opinions from a fresh viewpoint. Nice gallery too.
Finally let’s not overlook the excellent display of work donated by our members to the Wessex Heartbeat charity.
Next month is the last chance to make a donation before the presentation at the Heartbeat Dinner where our efforts will be auctioned.
