Instructables

Step 5: Log truss template

We purchased a number of 1/4 inch sheets of plywood and tacked them together covering a large enough area to actually sketch out each truss using the logs we had available. 

We marked a center line for the tie log and a center line for the king post.  We also marked where the rafter was to intersect the tie beam as well as the point where the rafter would project to connect with the other rafter on the top.

Each log was checked to see how it would be used on the site - checking for bow or sweep (although our logs were in really good shape because they were selected for this purpose).

Once we knew which side was "up" we marked the ends of the log with markings to show the "center" of it.  Note that the center does not necessarily end up in the center of the grain.

Using half of the butt diameter we marked on our template one half of the height on either side of our center line.  Repeat for the top end of the log.

We then snapped chalk lines to show, in general, where the log surface would fall. 

Repeating that for the king post was the next step.

Now we had a full-size sketch of the intersection of the king post and the tie beam.  We chose to make a 3 inch deep notch in the tie beam for the king post to sit in. 

The fourth photo shows in red the cuts necessary for both the king post base and for the center top of the tie beam.  We could now use our template and measure from the center of the king post index line to the outside to determine the width of the cut on the tie beam and how much to notch on the king post. 
 
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