The April meeting was a demo by Paul Bellamy, and you can read more about that in the previous post in this blog. It was, however, also a meeting where quite a few club members brought some of their work, and we ended up with nice display. Have a look at the pictures below.
Last Thursday we had Paul Bellamy as a demonstrator. Paul has been in woodworking and turning for a very long time, and brought his own lathe. His subject for the evening was “a bowl from a plank”. This is essentially a method where he cuts rings from a thin blank in such a manner that they can be glued together in reverse, thus forming a conical rough bowl. Once the glue has set, this can then be finish turned. A few minor variations in shape are possible, but obviously the basic shape is predetermined. He pointed out that for people who have access to cutoffs from furniture makers, and didn’t want to spend the time to dry their own wood or the money to pay for bowl blanks, this was a way to get by.
He showed us a few of his bowls, and then proceeded to draw a diagram to explain some of the basics. Essentially in each ring the bottom surface has to match up with the top surface of the ring underneath (see picture). For different thicknesses of planks (and desired height of the bowl) this then determines the cutting angle. He pointed out that despite best efforts one needs to allow for inaccuracies during the cut and also during the gluing stages, and therefore the rings should not be made any thinner than 3/4″.
He then made an actual drawing of the dimensions of the board he was using, which happened to be one inch thick. There is no need to determine the actual angle, all that is needed is to scale up the drawing. He did this on an A5 sheet of paper, simply multiplying both dimensions by a factor of 4, and then drawing a straight line from one corner of the rectangle to the opposite corner (the rectangle being 4″ high and 3″ wide).
He then turned his blank into the round (it was mounted on a screw chuck with the hole not drilled all the way through). The first thing after that was to turn a recess into the board, to create a chucking point for the assembled bowl. This recess was turned, sanded and finished completely.
Next the piece of paper was fixed to the banjo by way of a small magnet, with its long side aligned with the lathe bed. This allowed him to orient his parting tool along the diagonal line, and therefore give the exact angle at which he needed to cut. The first few cuts with a bowl gouge simply removed the waste on the outside, and he then used a 3mm parting tool to cut the rings. He explained that the best tool here is a 3mm tool with a relatively small width, as, especially on the smaller rings) the curvature of the ring does interfere with the blade cutting in, and therefore the cut had to be widened to allow for this.
Here you can see him cutting the first ring. This obviously requires a degree of skill, since the tool will ultimately hang over the tool rest by quite some way, and therefore speed should not be too high, to prevent heavy catches. This cut needs to go almost all the way, and one must stop as soon as one can feel the wood giving slightly under the pressure. He used his finger for this, which he claims is the best feeler of all.
He then stopped the lathe and put several pieces of gaffa tape onto the outside of the blank, covering the slot. Due to size restrictions he then took the entire chuck off the lathe so he could move the banjo onto the inside, put the chuck back on, and then very carefully cut with the parting tool the remaining distance from the other side. The tape held the ring safely in place.
He pointed out that once the ring is removed, its edges, and also the edges of the remaining blank, tend to be very sharp and needed to be handled with care, if not trimmed off slightly.
This action goes on until all rings are cut, usually 3 or 4 depending on board thickness and diameter.
Once all rings are cut, they need to be glued together, but in reverse, i.e. stacked on top of each other such that the flat surfaces match up. He uses Titebond Polyurethane glue for this, the reason being that it expands slightly and fills any voids, thereby creating a better bond. He has made himself a little jig for this, consisting of two large square pieces of kitchen counter, with 4 long threaded rods and wing nuts. Glue is applied to each surface, the rings are carefully stacked, using the fingers to ensure they are centered as well as is possible and then the stack is moved gently into the jig. It is important to apply the pressure evenly from all 4 rods, and to check regularly that the rings are not “swimming” away during this process.
Paul then moved on to a previously glued stack. He used the screw chuck (the hole in the bottom ring is now on the inside of the bowl) to mount the bowl again, and then started to refine the outside shape of the bowl. This requires small cuts, as the screw chuck only has a little hold on the assembly. Once the outside is finish turned, with whatever variations in shape are desired and possible, it is sanded and finished. The assembly is then reversed and now mounted onto the recess, and the bowl is turned on the inside.
Paul prefers bowl gouges with only a short wing, almost a traditional grind, and explained that this is needed to get around the curve at the bottom of the bowl. With a carefully controlled cut no scraping is required.
He also explained his various little tricks, such as always keeping his sandpaper in the right order of grit, thus only allowing the roughest grit to acquire a dusting. He uses lots of little magnets everywhere to make sure his little helpers (such as rulers etc.) are to hand when needed, and not covered with shavings. He never uses large pieces of sandpaper, and recommends moving in a continuous action from one end of the bowl to the other, so as to avoid any burning or heavy sanding marks, pointing out that sand paper should not be used to define the shape of a piece, it should only ever be used to remove tool marks.
He recognises that many finishes are possible for these bowls, but for demonstrations always uses melamine lacquer, simply because it dries very rapidly and provides a very smooth finish with medium shine. This can then be improved on with a stick of carnauba wax, which is simply run across the surface several times, and burnished with a piece of paper.
All in all, a very enjoyable demo, with Paul paying good attention to the needs of safety and always making sure he brought his whole audience along, including any newcomers.
On 18/02/2016, Dawn Hopley came to the club to do a demo for us.
Dawn has a background in industrial design, and has designed many items that most of us will have seen in many places, such as streetlights and car parts. After many trials and tribulations, including a stint as a teacher, she ended up in woodworking and woodturning. In order to use our camera and lighting rig, we had to move her lathe onto the rig, which made work a little awkward for her, as the rig was made for average size people, and Dawn is a little shorter than most of us. She put on a brave face and managed to make it work for her.
This was also the first time we used our TV display, and although this worked well, we probably need to learn a little more about the cameras. The picture was good, and all present could clearly see her tool technique, but the work piece was generally overexposed and just showed as a white blur. Clearly there’s room for improvement.
Her demo on this evening covered primarily the making of wooden containers for small perfume bottles, which she sources from a company called Ampulla. Apparently, when bought in bulk, these can be as little as 20p per bottle with screw lid.
Most of her work is done in small diameters, usually branches of trees, of which she had a variety with her. She demonstrated the ease of using a steb drive centre mounted in a normal chuck and emphasis was given to using sharp tools.
Dawn started out with a piece of yew, about 2″ diameter and 8″ long. It was mounted between centres and rounded with a roughing gouge. Then she turned two tenons on the ends and parted it off about 1/3 from one end. The longer piece was then mounted in the jaws, and the face cleaned up with a spindle gouge. Next she used a 19mm drill to create the opening that will hold the perfume bottle. As these bottles vary slightly in diameter, this hole then has to be carefully widened a little to just accept the bottle, and it has to be deep enough so that only the shoulder of the bottle just protrudes (although it can also be hidden entirely in the container). For this, Dawn demonstrated the use of a box scraper and some simple wooden sticks with sand paper wrapped around them. Once the inside is finished, the outside is shaped with the spindle gouge to whatever shape is desired. Some accents were made by cutting small grooves with the pointy end of a skew chisel and then burning black lines with a cheese cutter (essentially a steel wire with two wooden handles on both ends).
The top is made in exactly the same way, with the main focus on remembering that there is a hole inside large enough to hold the screw lid for the bottle. When that hole is drilled and cleaned up, it is essential to ensure that the wooden parts will meet before the lid sets on the bottle, as otherwise an ungainly gap appears between bottom and top. In addition, Dawn usually adds some detail to the bottom of the lid, in order to hide the meeting place between the parts.
In order to finish the very top of the lid and the foot of the bottom, Dawn demonstrated the use of jam chucks. These are essentially pieces of scrap wood with a tenon on one side, so that they can be held in the jaws. The other side is turned so that it will provide a tight fit to the holes prepared in the bottle parts. When the fit is not quite tight enough to allow cutting, it can be improved with one or two layers of masking tape or tissue paper. In this way work pieces can be held without creating any jaw marks, and just sufficiently tight to allow small cuts, sanding and polishing.
Overall, a very enjoyable demo, especially for the visitors and less experienced members, who could see that even with very few tools and a small lathe very nice results can be achieved. Turn out on the evening was great, and it seems that our increased demo fees have not deterred anybody. If anything, we had more people show up than I ever remember before, including some visitors and new members.
There were not many pieces on display this evening, but a very nice apple clock and some sewing kits drew some attention.