19/6/12

So this morning we went up stairs to learn more about Trigonometry.We were given a few mathematical equations that we had to solve.We used SOH CAH TOA,Sine,Cosine and Tangent.We were given an angle to work with along with a side to a triangle.For example,16 degrees with an adjacent of 300 and we are to find the Hypotenuse,The longest side.So we use CAH.300 divide by cos16 = 312.08, This is how you get the H side in this equation.

Sides of a triangle.

To find an angle,It is a little bit different.If we have two sides,Lets say,For our opposite,we have 1080 and for our adjacent,we have 7200,We go 1080/7200 =0.15  Then 0.15tan-1 which will give us the and of 8.53.





After the session in Class we resorted back to the E-Shed.My assigned group was to continue with the Gable Roof exercise.I started with making the Raking frames for the build,Then moved onto making the Outriggers,There are 3 out riggers on each side of the Gable roof,They are evenly spaced out and nailed into the rafters on the inside of the roof so that the fly rafters can be attached at the end of the roof on the outside.They also have plumb cuts at the top so that they can evenly join up to the Ridge board.With the Raking frame,We have studs that run from the bottom plate to the top of the raking plate with the top being on a 40 degree angle.For the center stud,we have 2 40 degree cuts on the top so that it sits flush within the top of the raking plates.Once all fit nicely we skew the nails through to sercure it all into place,I used 3 inch nails as this is only a small exercise.

Tomorrow we should have the task complete,All we have left to do is the purlins down the far end along with the fly rafters.Then we can get back to the house build.Mostly all the purlins have been installed to the house trusses,Attached with 2 4 inch nails top and bottom and a purlin screw in the middle,The nails are hit in on angles to prevent uplift of the roof in ruff weather conditions.

18/6/12

So this morning,We all lined up for class with Mark.We went back over the session we had last week in regards to the Roofing.Rafters and Trusses.We went over various terms for each section of a rafter set up.

After smoko we were split in 2 groups and one half of the class were to proceed with the Purlins while my half were put on the roof making task,we went back over SOH CAH TOA,We were given an angle for our roof,ours was 40 degrees.The width of our building was 2000mm,and the length was 2400mm,we halved the width,so 1000mm,We needed to find the length of our rafters.So,The method we used was,CAH as we needed to find the longest side.So Cos40 x 1000,That gives us the lengt of the Longest side,(The rafter).We used a sliding Bevel to transfer the angles to other rafters.A hand saw was used to cut them down to the correct lengths.We then had to cut out a piece known as the birds mouth.Matt showed us how to do this,For our roof,I measured out 1288 and marked a line,Then from the line I transfered it with a sliding bevel with 40 degrees.Then moved the bevel to the end with the builders square and adjusted it then moved it back forming the piece(Birds mouth) which is to be cut out,Once it was cut out,the rafter can frimly sit flush onto the top plate of the building.

Outriggers being nailed off.

Working out how to cut out or birds mouths.

Once all the rafters are cut,They are evenly spaced then attached to the ridge board at the top.We then skewed the rafters down.Tomorrow we will finish the building exercise,The Purlins should be attached and the raking top plate will be finished.Then we will be ready for marking.