Basic Hand Tools
A Straight Line - Setting a String Line
A straight line is the shortest distance between two points.
A mason and/or carpenter uses a string line between two points (nails, the line holder, or line blocks...) and the line is pulled tight to get it the shortest distance, to make it straight, with no sag.
One can get accurate readings on a string line, by using three small packers, all the same thickness, say 20mm. Stretch a line between two end points that are fixed first. Then put a packer under each end to give the line clearance.
A straight line is the shortest distance between two points.
A mason and/or carpenter uses a string line between two points (nails, the line holder, or line blocks...) and the line is pulled tight to get it the shortest distance, to make it straight, with no sag.
One can get accurate readings on a string line, by using three small packers, all the same thickness, say 20mm. Stretch a line between two end points that are fixed first. Then put a packer under each end to give the line clearance.
String Line between two joists
- In the image above, are two fixed joists 'A' and 'B' with a 20mm packer under the string line at each end.
- A third packer is utilized as a gauge to check the height of the rest of the joists. At 'C' he can see that the joist is too high. This is a common basic method used on walls, ceilings, formwork,... If you don't use the packers, there is a danger of each joist lifting the line a small amount and you finishing up with a curve.
- A long run of string may get sag in the line, pick a point about the center and pack it up as you sight along the line from the end that looks straight. A good string line should have a fair amount of stretch in it.
Off Setting a String Line
- Shown in the image above is another method of using the line with an offset.
- Marking out a profile (left), a building line to prepare for a new extension, in an exact, squared straight continuation of the main wall of the existing building or structure.
- Picking a distance from the Building or Structure that gets you clear of any possible obstructions. In the image above 145mm.
- Making sure the string line is offset the same distance from the Building or Structure, putting a nail or screw into the profile at the continuation of that line.
- Then measuring back the offset distance to get a point exactly in line with the wall.
- Put a nail into a brick joint or a peg touching the wall, string a line (dashed above), to set the true building line.
Plumb Bobs and Plumb Levels
In construction, carpentry or masonry, the term "plumb" or action of making something plumb; has little to do with the trade of a plumber, at the same time it has everything to do with it. As a plumber has to plumb pipes and at one time in history some pipes were made of lead. Known to cause lead poisoning. The word Plumb derives from the Latin word for lead, plumbum. (pb.) and the practice of finding true vertical by hanging a lead weight from a string. The lead weight that is hung from the string is called a Plumb Bob and was usually centered and pointed. As you can see in the image >>> Plumber derives from the same source, because plumbers were the people who worked with lead. Lead roofing and lead water pipes etc. A String Line Brickie's or Mason's Plumb Level - is just a straight piece of timber with a hole cut in the bottom where a brass or lead plumb bob swings. Usually about 4 ft. >>> To use it, you simply rock it slowly towards you once or twice or until the bob swings free back and fourth slowly; then allow it to swing freely until it comes to a rest. Do this a couple of times and it steadies the swing and gives a true reading quite quickly. I am not saying let's start using these again, yet some old methods are quite adequate for some jobs. Wooden plumb levels work on occasions when needed. |
A String Line Horizontal Plumb Level - is made with a couple of pieces of wood screwed to the Brickies/Mason's Plumb Level (shown as dotted lines in sketch), making it a lot easier, no climbing... Why all the messing about with plumb bobs...? Formwork is never exact where you can use a spirit/bubble level on the outside, a bubble level can give a wrong reading. There are odd sizes of rough cut or bent lumber,...
When utilizing for concrete it must be narrower at the top than the bottom. <<< An image of a Mason's Horizontal Level that would have been standard equipment on any of the old cathedrals. It is the same as above with a cross piece added. Very simple technology used for creating incredibly complex works for many centuries. One of the most famous ~ The Salisbury Cathedral |
Transferring a Vertical Point or Edge with a Plumb Bob
Let's say that you have a first floor landing that you want to plumb down to the floor below so that you can start measuring setting a flight of stairs up.
- You must drop your plumb bob from the top and just as it touches the floor below you lift it up and down a couple of times slightly, not touching the floor allowing it to swinging free. This steadies the swing.
- Then when it has settled you slowly let it down into contact and let it lie on it's side. A well designed bob may roll at this stage, but it will only roll about the tip, (usually a steel point).
- When you come down from above, you mark the floor where the tip rests.
- You can repeat the process and get a straight line on the floor that is exactly under the edge above.
It is a one man operation and it can be done over a reasonable height.
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