Cog Joints for Right Tie Beam – green oak barn

Monday 15/3/21

Today we worked on the joints between the front and rear wall plates and the righthand tie beam. The techniques are similar to those used when cleaning out a mortice but you have to remember that in this case the depth is critical as the tie beam will sit on the base of this mortice.

Right rear cog joint

The hole exposed at the bottom of this joint is the mortice for the post that sits under this tie beam. With both of these cogs cut on both wall plates, we brought in the righthand tie beam. The two tie beams are the heaviest elements of the structure.

Laying up the tie beam

We laid the tie beam across the cog joints and transferred the marks for the tie beam element of the joint.

Marking the tie beam joint

These are the simplest joint element of the whole project. It’s a a pity there are only four of them!

Cutting the tie beam joint

We then put the tie beam in place on the wall plates: front and rear.

Tie beam wall plate cog joint - 2 Tie beam wall plate cog joint - 1

It was now time to play with the new toy – the drill guide! I actually bought this to drill holdfast holes in my workbench but I haven’t go around to this yet. But it’s the ideal tool for drilling the angled holes needed for the corner tie fixings.

Simon using the drill guide

Ben using the drill guide - 1

This video shows the drill guide in action, first drilling the recess hole for the head of the stainless steel fixing and then the 6mm pilot hole.

These are the fixings we are going to use.


A good day. Tomorrow we will start on the second and final truss.




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