Planing Cutting and Drilling archive
Wednesday 15 October 2008
These important techniques get explained by Michael Huntley
Last month we made a bench hook in order to hold timber steady while we cut it to length. I made certain assumptions about the timber that you might be cutting i.e. 50 x 100 PAR. One reader commented that understanding timber sizes and prices was confusing, so this month I have compiled a chart of common sizes and prices based upon a local timber merchant's current stock. Prices will change from merchant to merchant, but sizes won't as they are standardised. However, it is true that the bigger merchant will stock a wider range. Most yards will also get timber planed to size for you but you will have to pay extra for this service.
STICK TALKWhen buying, work out how many actual sticks you want. This refers to the common lengths. Let's say that you need a total of 25m of 50 x 25mm material. The merchant may have 3.6m lengths so will pull out of the stack seven lengths of this. But if you wanted 10 pieces of 2.5m each length, although you had sufficient total length you wouldn't have 10 individual lengths of 2.5m.
So from the cutting list you need to work up an order list that takes account of how many components you can get out of each individual length that you come home with.
And while you are down at the merchants don't forget to buy the glue, screws, nails and sandpaper!
ACHIEVING FLATNESSOK, now there's a pile of timber on the drive, the car is parked in the road so that the garage is available for woodwork - what next? Last month I wrote about flatness. Ideally you need somewhere to lay the timber and check for bowing and twisting. It would be nice if all timber came perfectly flat - lots of projects don't work out as expected because the timber wasn't consistently flat and true.
WHAT YOU NEED IS...... a pair of trestles. Now, you could make the fancy ones that carpenters use but that involves joints for splayed legs which are a bit complicated, so we will just make what is known as a pair of hop-ups.
These can be used to stand on, place timber on for sorting, put timber on for rough cutting and also, which is what I want them for today, placing a flat worktop on top of them to form a temporary bench - we'll make a real bench later in the series. If you have a Workmate, make the hop-up to match its height.
MAKING HOP-UPMaterials to make 1 hop-up: 3 off 1.8m - 25 x 150 PAR softwood, 1 off 1.8m - 50 x 75 PAR softwood.
USING HOP-UPPlace the sheet of 1200 x 750mm MDF that I referred to in WPP12 on top of the trestles and check that it is not bowing in the middle. Lay out a few of your timber sticks and pick the flattest face.
Also check for splits and knots.
Try and find the 'perfect face', one which has no defects, no twisting and no bowing. Now write the word FACE in pencil on your selected faces. Having found a good face and checked it with the level or straightedge, you now need to find an adjacent edge that is 'perfect'.
Looking at a single piece of timber lying on your temporary bench, it can be either the near edge or the far edge, but the good edge must touch the good face.
Check down its length for straightness and, using a carpenter's or engineer's square, check that the edge is at 90 degrees to the 'perfect' face. When you have found your 'perfect' edge write EDGE on it in pencil.
It may seem tedious to have to do this for every stick of timber, but let me assure you, every maker of hand-built furniture in the country selects his or her timber this way. They use symbols for face and edge and grain direction rather than words, but the principle is the same. You have to get used to selecting the best surfaces to work with. So far we have only been working with pre-prepared timbers, but you may have to cut timbers to size and that would require planing up a face and edge yourself.