Friday, 16 May 2008

My Desk - checking and grouping the rectangles

Having transported all the wood home, I double-checked all the dimensions, and grouped all the rectangles into little piles that go together - one for a drawer, one for the left unit, etc:

I decided to start with a small drawer. I'd purchased some cam and bolt fixings for connecting edges together, but it quickly became apparent that this was not a good choice. I made two holes for two cams on the back piece of the drawer using a forstner bit of the required size, and holes for the matching bolts with a wood drill. The holes for the bolts probably need more precisely-sized holes than I could drill with my integer-only millimetre drills, as the bolt didn't screw in easily, and that caused the veneer to raise up into a mound around the bolt. It was also a lot of fuss to get the cam hole in the right position and to the right depth. Everything was going to take far too long at this rate.

So I made a Plan B, and went out and bought a dowel jig and some dowels. Holes for dowels were a lot quicker to make accurately using this, and I quickly had all the pieces of the drawer held together. A bit of gluing and clamping in the jaws of my workbench over a couple of nights and the drawer carcass was done.

Next came the glue-on veneer edges. This task is very satisfying - it's really easy to iron the strips on, trim off the excess with a plane, then sand the edges smooth, and get a really good finish.

Here's a photo of the end result:

The dark areas on the back edges you can just make out in the picture are what happens if wood glue touches the veneer - it stains it.

Saturday, 10 May 2008

My Desk - making it happen

Apart from the desk top, it's all rectangles. To look good, all those rectangles need to be cut accurately to size and squarely. I have a circular saw that cuts reasonably straight, but the propect of carefully marking up and cutting all 36 rectangles from large sheets was enough to put me off ever starting the project. Plus the circular saw doesn't cut a very neat edge. This is where the cunning plan comes in...

Ridgeons, where I was planning to get the wood, has a large wall-mounted saw which they can use to quickly and accurately cut sheets of wood. I reasoned that if I made a cutting plan for the required number sheets, I could pay Ridgeons to do this bit for me, and then all (all! hah!) I'd have to do would be to fix the rectangles together to make a desk.

I like oak, but solid oak is expensive and would probably split or warp if I tried to make a desk out of rectangular panels of it, so I opted for oak-veneered MDF, as used in the construction of the Billy bookcases. Ridgeons sell it in sheets of 2440mm by 1220mm, so I set about arranging the required rectangles onto sheets, trying to minimise wastage and number of cuts.

At first I tried to use Sketchup to rotate all the rectangles into the same plane and fit them to sheets, but that turned out to be quite tedious, so instead I manually copied the size of each rectangle into a spreadsheet (hiding each in Sketchup as I copied it to avoid missing or duplicating any), then used OpenOffice Draw to create a 2D drawing of all the rectangles (labelled and colour-coded for easier checking), and arrange them onto sheets. Here's one of them:

The chap in the timber cutting section at Ridgeons told me to allow 4mm for the cuts, and explained that it's difficult to make cuts that stop part-way across a sheet. The small white circles on the sheet above are numbers, indicating an order for the cuts that ensures each is a cut right across a sheet.

The shape of the desk top I would need to cut myself, but I thought I could manage that as it would only be a small number of cuts. The top would be too large to cut from a single sheet, and also too large to fit in my car, so I split it into three parts, and added rectangles of the required size to the cutting plans.

I chose sheets with crown-cut veneer, which has nice patterns in it, on one side, and cross cut, which has a plainer pattern, on the other, planning to use the crown-cut as the more visible sides of the desk.

I took printouts of the cutting sheets (four in total) to Ridgeons, and they quoted me a discounted price of £15 for the cutting, and about £250 for the wood. £15! A bargain! Think how long it would have taken me to cut them myself!

I collected all the cut rectangles (and the off-cuts) a day later, and took them home in the back of the car (a hatch-back, with the back seat down). The spreadsheet of rectangle sizes was useful for checking everything was correct. In general, the accuracy was pretty good. I found two or three dimensions that were 1-2mm out, which was a little disappointing, but will probably be ok.

Another slight disappointment was that the sheets had been cut with the crown-cut side on the side of the saw that produces more splinters, and for the cuts that went across the grain this meant the edges were quite ragged. As a result I decided to use the plainer cross-cut sides for the more visible sides of the desk, hiding the more ragged edges.

The final disappointment was my fault. I put the rectangle for the filing-cabinet top onto the cutting sheet the wrong way round, so the grain goes the wrong way when compared to the desk top. If this looks too bad then I could get another one cut (perhaps with some more rectangles for future projects...), but I might just leave it as one of the "features" of a piece of home-made furniture (and it won't be the only "feature"...).

Next-up: fixing the rectangles together...