Posted by jerry on December 28th, 2008 — Posted in Music, Woodwork
While I successfully used a piece of water pipe and a blow torch for forming the sides of my travel violin, I felt I needed something more reliable for the mandolin. I had read of the possibility of using a heat gun – the sort used to strip paint – to provide a steady heat source, but saw no plans for doing so.
It was time to think it through and find my own solution. And here it is.
Please note that the air needs a place to escape so that the end of the heat gun doesn’t melt. But the solution is a durable one.
The pipe structure comprises an internal plug with a square top – which is held in the vise. Attached is an T-junction connector, with one opening towards the heat gun, the other vertical. To the vertical end is attached a short piece of water pipe using a connector. And that’s it. The heat enters the wider aperture of the T-junction, finds the lower aperture plugged, and diverts up the vertical tube. The vertical tube is narrower than the T-junction, so the tube gets to be heated, while waste air is released out the top – away from the person doing the bending.
On the hot setting (600C) the vertical tube is plenty hot enough to boil water on contact, but because the waste heat can escape, there is no heat buildup to melt the heat gun, and there is no hot blast of air against the body of the operator.
The proof is in this piece of binding which was used to test the bending iron.
Here is the upper strap arrangement with padded shin/knee cup. The screws holding the shin cup go through the webbing for the straps – which are made from high quality seat-belt material.
The boots give the best support and hold for the feet, if the stilts are for one person and you can sacrifice a pair of sneakers or boots – boots are better for ankle protection.
Here is the underside of the foot plate – as you can see the main leg shafts are directly beneath the ball of the foot and quite central so the forces are mainly vertical.
And here is the finished set. The timber is finished with one coat of orange shellac and then wiped over with orange oil to feed the wood and keep out moisture. They are made from straight grained pine with no knots, and are 1.8m tall to the base of the foot plates. The leg timbers are 32mm x 42mm x 1800mm (1.5″x2″x6′)
Many of you would know I’ve been busy latelymaking a mandolin. Today I encountered a slight obstacle. I was cutting some thin strips for the ribs out of Tasmanian blackwood and got partway through the first cut when there was a thud and suddenly the saw was working very hard. I hit the stop button and assessed the situation. It was a classic mistake. I hadn’t considered the width of the gap between the saw blade and the table – which is quite wide on the triton mark 3, and the thin strip dragged itself down between the blade and the tabletop.
I pondered this for a bit and remembered the solution – make a zero clearance sacrificial table. I had some 3mm MDF (medium density fibreboard) and found a piece about the right size – enough to cover about half the triton saw table. I set the blade to the height I wanted for the cut, then I removed the guard – note if you do that you need to be absolutely focused on your safety. I positioned the MDF above the blade, started the saw, and with one edge braced against the riving knife I lowered the MDF onto the blade, making sure that my hands were well clear of where the blade would cut. I then stopped the saw and there was the false tabletop with zero gap between the saw blade and the MDF. I clamped cut a slot for the fence bolts, then clamped the MDF in position and set the desired gap between the fence and the saw blade.
At that point I replaced the blade guard and made a trial cut in a pine offcut before going back to the precious Tasmanian blackwood, ready to make the thin strips that will eventually become the sides of the mandolin.
This exhibition of the latest woodworking equipment, demonstrations and stacks of timber is one of the must-see events if you are a woodworker – whether hobbyist or semi professional.
As you arrive, there are demonstrations of the Lucas saw mill, and the Swedex Logosol mini saw mill. This latter made short work of a large log using a chainsaw mounted in a frame that holds the saw horizontal for cutting slabs. The whole thing is adjustable for slab thickness and slope of the log. Very impressive for such a small mill.
Once inside I went in search of lumber – I have in mind to make a couple of musical instruments – another pochette fiddle and a travel mandolin. Trend Timbers was my first and primary stop as they had some lovely birdseye maple and rosewood. I also found blackwood, silkwood and purpleheart. But alas no spruce. It seems I have to go to Sydney for that, or order it on the internet. I also got the last piece of American sycamore in captivity in Canberra.
The guys there were very friendly and helpful – they even helped me carry my acquisitions to the parcel pick-up place. And I learned that Brazil is the only country to be named after a timber! Brazil wood was known before the country had a (Western) name.
There were great demonstrations and seminars – don’t miss the chair making one by Richard Vaughan titled ‘Seat yourself’. Richard Raffan and Bruce Bell did wood turning demos and Roger Givkin showed off his dovetail jig and demonstrated the art of small box making.
While there are many great new toys out there, one really stood out for me this year – the SawStop. This is amazing and will save countless fingers from being injured by table saws. A small electrical current passes through the saw blade, and trips a sensor as soon as the blade touches flesh rather than wood. Within 5milliseconds – ten times faster than a car airbag deploys in an accident, and seven times faster than we blink, a gas charge propels an aluminium brake into the saw blade and the whole blade drops below the table. I just had to film this demonstration:
I hope every educational institution teaching woodworking buys this as it will save countless hands from serious injury.
There was a great selection of books at the Australian Woodworker stand – and you could pick up any back issues you missed on the news stands.
If you are into bush crafts there wasStan Ceglinski with his crosscut saw race – but he is also very skilled with a riving knife too!
There were also demonstrations of pole-lathe woodturning
and demos of chair making by a master bodger using green wood and a draw-knife
If you are into boats – then the Cape Boatworks is a must visit – they are building a canoe from wood strips through the course of the weekend. It’s the first day and the canoe is already well advanced!
And I came away with new knowledge – and a small stash of rather special timber
I’ve been turning more pens today – I shall be visiting some special friends next week and wanted to bring them something connected with Australia. What better gift, then, than a pen hand turned from Western Australian jarrah.
The timber is hard and brittle, but takes a wonderful finish when turned, burnished and polished. I cracked three of the blanks during the turning process and one during the assembly process – so I had to remake the blanks.
I wanted to achieve a design that would sit nicely in the hand – a shape that that would mold itself to the hand. And this is what I came up with – what do you think?