How does a carpenter use geometry?

Question

How do they mostly use perpendicular lines and measuring angles.

Answer 1

A good carpenter must have at least some understanding of geometry. Let me give three examples:

When building a house, the carpenter must ensure that the walls are square and perpendicular to one another. For convenience in this example, let's assume that the house is rectangular. When doing the initial layout on the foundation, the carpenter first marks the locations of the corners of the exterior walls by measuring equal lengths for opposite sides, which defines a parallelogram. Then the carpenter measures the diagonal distances for these corners. The walls are perpendicular if the diagonals are equal. If they are unequal, the carpenter must adjust the position of the corners until they are equal. The parallelogram is now a rectangle. The carpenter will now permanently mark the location of the exterior walls by snapping chalk lines on the foundation. The interior walls are now located by measuring from these chalk lines.

Although the design of the stairs is usually shown on the construction drawings, the carpenter must make the final adjustments to fit in the space allowed. The individual steps are attached to long boards called stringers that run from top to bottom of the stairs. There are usually three stringers: one on each side of the stairs and one down the middle. The stringers have large notches to accommodate the steps. The carpenter must use his skill to make the notches the right size and depth, and at the right angle, so that the steps fit correctly and are level.

The roof is perhaps the trickiest part to build, especially if it is built from scratch without the use of prefabricated trusses. The plans may specify the slope of the roof in terms of rise over run. For example, the slope may be 5 in 12, meaning 5 inches up for every 12 inches horizontally. From this, the carpenter must determine the placement of the ridge (top of the roof), and the angle and length to cut the rafters. He must also determine the compound angle cuts for the hips and valleys.

Answer 2

1

Answer 3

never mind a house, imagine you're building a bookcase. ignore the shelves for now. suppose the back board isn't exactly all right angles; what do you end up with? a leaning bookcase? wasted material? once you have that, how bout the shelves? go ahead, use an angle that's not a 90 degree angle. your books won't be standing up straight very long. the bookcase may even give people motion sickness (huh? i'm seeing everything tilted!!!)

even if you did want to build a bookcase that's more wide at the bottom, and narrow at the top, you better get those angles exactly the same at the bottom, or otherwise you won't have symmetry. no symmetry=looks crooked=garbage.

so take all i've said and apply it to a larger scale if you want, such as a whole house, a whole room, etc. because a house is mainly a bunch of rectangles! (or cubes, if you look at the space rather than the walls). and if your'e talking about cubes, now you need to get 8 right angles...

funny thing is, a one degree mess-up, applied to some 20' (length of a living room) of material, turns into
tan 1 = x/20'
x=.35' or x=4.2 inches
if the other end of the wall of your living room is 4.2" off from where it should be, you got problems...

Answer 4

Carpentry Geometry

Answer 5

If they are building a house they need floor plans. You can't just BUILD a house with no knowledge of geometry

Answer 6

well when they are building a table for example, then they would need precise measurements and they would need to draw a model diagram first. The corners may have triangular shapes, so they work heavily with geometry.

Answer 7

The most commonly used angles used in carpentry are 45 and 90 degree. Ever look at a door frame? those are cut at 45 degree angles. You have to be able to add subtract and divide in order to build something. You also need to be able to use fractions. Look at a tape measure and you will see it is broken down into inches half inches, quarter inches etc.

Answer 8

If they never used geometry everything would look like it was from a Dr. Seuss book or something.

Answer 9

what?... what about wooden knobs?... or dollhouses?...