Saturday, June 18, 2011

Several steps to create a nice curved edge.

They say variety is the spice of life... so my work load is pretty spicy!
I am currently making a big Break-Fronted Art-Deco Style Bookcase from recycled timber. My customer Norelle has been doing a big renovation on her house, which was built during the Art-Deco era here in Perth, Western Australia. The timbers removed from the house were fortunately saved, as Norelle was keen to have them recycled into furniture rather than going into landfill which is tragically too often what happens around here.

This piece of furniture is going to be a stunning feature in the living room. At 3.3m long (about 11 feet) and 2.8m high (over 9 feet) it will take up a big piece of wall. It will be made up of three sections each 1.1m wide, sitting on a plinth, and topped with a crown mould which echos a detail in the neighbouring architraves' tops. The nice curves on the face edges of the end panels and the break-front panels will help give it that art-deco feel. These will also be reflected in the plinth and the crown mould.

The Challenge.
It's those curves which were the challenge before me. When the 25mm thick end panels were glued up, these included a broad edge strip which beefs up the front edge to 50mm. A butt joint strengthened with a spline of 1/4 inch ply. The splines were also used to joint the middle end panels to bring them to the required 300mm width. Nice. I would normally cut the groove on my table saw, but as the sticks were so heavy I used a 1/2 " x 1 " slot cutter in the router.
It is this broad edge strip which would enable me to create the desired curve. See the plan below:

Having glued up the end panels, the challenge was to create the curve with a 40mm radius. I don't have a spindle moulder (shaper) with a whopping great 40mm radius cutter, and such a cutter would be too big for a router. So it would come down to a combination of hand and power tools to create the curve. There were 4 end panels to shape the curve on, each along more than 9 1/2 feet of hardwood.

Background to the timber I'm using.
The timber is I have to work with is jarrah (Eucalyptus marginata), which was used for almost all domestic housing (and everything else) here for over 150 years. The timber removed from this house which I have to use for the job is mostly made up of hanger beams (9" x 1 1/2"), heavy joists (8" x 2"), and rafters (4"x2").

The timber pile in my customer's front yard. I selected, docked and de-nailed right here.
The selected timber docked and stacked in my front yard ready for cleaning and machining. 

The timber recycler's machine's best friends: a wire brush and a metal detector!
Preparing and machining the timber for this job is a story in itself, which I won't get into here. However, the result was a bunch of boards about 8" wide and 26mm thick, at either 4 feet long or 9 1/2 feet long. The short ones are for shelves, and the long ones for the end panels. There's a number of 4"x2"'s at 9 1/2 feet long, ready to transform into a heap of V-joint lining board (for the backs of the cabinet) and to make the front edges of the end panels. The 4"x2"s also gave me the 40mm x 50mm sticks to be glued to the front edges, in order to create the beautiful Art-Deco rounded edges - the curves I needed to shape.

Jarrah is a beautiful timber. Here in Western Australia, about 80% of the timber I use today is still jarrah. Twenty years ago it made up about 95% of the timber I used. I know the stuff very well. The difference is that twenty years go almost all of that timber was new - whereas now days about 90% of what I use is recycled. The supply is rapidly dwindling, the dimensions available are getting smaller, and the cost of new timber is spiralling upwards. I suppose I am also very committed to good stewardship of the resource which is already out there... but that is another story worth writing about sometime. I digress.

As a comparison, European Oak has an ADD (Air Dried Density, at around 12% moisture content) of about 700kg/m3 - a little less than North American Rock Maple at 730kg.m3. Jarrah has an ADD of around 820kg/m3. (Source: "Wood in Australia", K.R. Bootle, 1983).

Preparing the panel ends ready for shaping.
Doing big glue-ups is always a challenge in my tiny workshop - especially when it is raining and I can't spill outside the workshop door! I have to plan my glue-ups and other processes, but I am helped by the wonderful properties of the Titebond 3 glue which I use for just about everything. The short open time is the price you pay for the short cramping time. If I keep the cramps on for 2 hours, I can do 3 or 4 glue-ups in a day.
One of the narrower end panels being glued up. The left stick is just protection and to spread the cramping pressure.

Cleaning off the surplus glue, topside, with my trusty Record 0110 block plane.
A cabinet scraper cleaned surplus glue from the underside of end panels. Note built up front edge.
With the end panels prepared (and "over-long" - not docked to length yet) now the challenge would begin. How do you create a nice consistent curve with a 40mm radius along the front face edge of these four end panels? It was going to be a multi-stage process...

Tooling up for the job - making the scraper-gauge.
There would be several things I would make in order to create a consistent curve.  The first thing was what I would call a scraper-gauge, a bit like a scratch-stock.
Start with a block of wood. Cut a 40 x40mm rebate out of it on the table saw. Save the offcut.

Use a bit of sawblade or a scraper to mark out a 40mm radius on the corner. Cut and grind to shape.
Drill or punch holes in metal, and fix to block in right pozzie with binding head screws.

Screw the off-cut onto the side, offset about 3 inches. The inner surfaces are flush. Tool ready.
Let the shaping begin!
Three more special gadgets were made to help with the task ahead, and then it was time to commence.

Firstly, my small power saw was set up to cut off some waste at 45 degrees, tangential to the curve.
 
A wooden guiding jig screwed to the base plate of a power saw, to cut a tangent at 45 degrees. 
Nice little Squirrel Tail Plane with a concaved base helped remove more waste.

A curved cabinet scraper made from a saw blade and the scraper-gauge ensured curve accuracy.

Curved sanding block made from scraps, about 41mm radius to allow for paper thickness. This completed the curve.

The finished article - what a nice curve, along the whole 2.9m length. Delicious!

So there you have it. Not such a challenge after all. It was a multi-stage process, but with a combination of tools both off the shelf and custom-made, the task was completed beautifully. Other than the initial 45 degree cut with the power saw, the shaping was all done by hand. One down... three more to go...

Stay tuned for more stories in the making of this bookcase.

Just a parting thought... about that nice little squirrel tailed plane. A variation on the Stanley No.100. It was made by my late Uncle, Ray Miller, who passed away a few weeks ago. A very clever and talented woodworker and boat builder, he was very skilled at metalworking also, and was renowned for his ability to make specialised tools and jigs. His passing was a loss to the woodworking world, especially the tall ship building fraternity in Fremantle, as well as to his family. He had given a set of three of these small planes to my father some years ago, and now Dad has given them to me.

I am now the next custodian of these beaut little planes, and they continue to be used to make things of great beauty.  

1 comment:

  1. "Preparing and machining the timber for this job is a story in itself, which I won't get into here."
    I'm sorry to hear that. It would be really interesting; these timber are usually badly warped, twisted, bent ...

    ReplyDelete