Above is an example of a tie beam to post connection.
There are some standard rules about joint sizing. For example the tenon thickness is 1/4 the beam width. So if you have an 8x8 then the tenon is 2" or 1/4 of 8". If you have an 8x12, the tenon is still 2" as it is 1/4 the thickness.
The peg size is then 1/2 the tenon thickness, so it would be a 1" peg.
For a smaller frame such as a 6x6 beam then the tenon is 1 1/2" and the peg is 3/4".
The next standard is the reduction. The reduction is the amount that the 8x8 is reduced to a standard size so that the joints will fit together.
We normally do 1/2" under the requested size. So if it is an 8x8 the end is reduced to 7 1/2" in height. If it was a 8x12 then 11 1/2". The mortise and housing would then be 11 1/2" as well so that the timbers will easily fit together.
If you're interested in seeing all this type of layout and joinery come to the Old House and Barn expo next weekend in Manchester NH on Saturday the 12th and Sunday the 13th.
The guild will be cutting joints and erecting an 8' x 12' garden shed/kid's playhouse frame using all of these standards.
Here is a link to that event:
Check this out.
http://www.oldhouseandbarnexpo.org/old-house-and-barn-expo/Jim Rogers
