Saturday, October 16, 2010

55, Sill(Cill)(s) 2.

As fortunate as I was in the procurement of the window sills, (or cills if you prefer to spell them that way, I still can't make up my mind!), I was still left 1 short. This was needed for the side window in the main bedroom. The profile of my sills is a little different to the standard variety usually found in this part of the world. The shoulders on either side junction at a sharp 90 degrees with the upper sloping surface whereas on the common garden variety, of which I also have a small stockpile, they are concaved.
Not wanting to mix and match the sills on the house or cannibalise one of my other ones, I decided to make a new one from scratch.

The smallest stone in my collection with enough length to provide a sill of the required size, was, in a previous life, a capping stone. It came off the abutment of a small bridge located on the railway line near Little River, situated about mid way between Melbourne and Geelong. It was rendered obsolete many years ago when all the bridges and culverts along this line were strengthened, carried out by replacing the steel decks with new steel reinforced concrete ones. This necessitated the removal of the upper courses of stone and the installation of cast in situ concrete bearers.

Firstly I removed the rough back of the stone and then sawed off a slice about 5mm thick, (seen on the bench on the right). This was to ensure the soundness of the block, any unseen cracking would certainly become apparent on a piece this thin. Being happy with the result I then removed a suitable slab, cutting it about an inch thicker than needed to allow for final trimming.

I was a bit annoyed to find that a drill hole had been made into the base of the stone at some stage, for no apparent reason. The bulk of the original block, just shy of 600kg had made it a bit impractical to roll it over for a visual inspection. The hole ran about 3/4s of the way through and my saw cut had passed right across it. Fortunately though, with its angle and depth I was able to locate it within the waste area of the top bevel.

With the block positioned at the correct angle I then proceeded to make consecutive cuts about 1/2 an inch apart to remove the bulk of the waste.

The fingers were then broken and chiselled off.

The blade was then dropped slightly and the face tidied with the blade being moved sideways 1/16 of an inch after each pass.

With the bevel completed, the next step was to form the step to the front vertical face of the shoulders. I removed the bulk of the waste with a small angle grinder and then chiselled the surfaces true. Having completed these I then chiselled out the rebate to house the timber window sill at the top edge of the bevel.

Having all the upper profiles completed, the sill could then be trimmed to its correct dimensions. I started with the front face which received the same treatment as the bevel using consecutive saw cuts to emulate a tooled finish. This process testing out my sanity with a steady, continuous and monotonous 2 hours of back and forth for each face.

The Back, Head and Bed were next, with normal saw cuts sufficing.

The drip groove under the overhang could now be formed, taking care to stop short of the ends.

After some light chiselling to remove the radial saw marks on the seen areas of the trimmed ends it was ready to go!

3 days toil later and it's in its final resting place.