Placement of pegs or Wedges in a Kingpost truss

[mmhailey]

I am test fitting and I have a question on placement of pegs.  Here is a graphic of the design.





The plans I have show two pegs placed in the tenon of the Kingpost through the bottom chord. My problem is, I seem to remember from a discussion, that wedges are a better solution since they can be tightened as the beam shrinks.  I looked in my copy of historical American Timber joints, and I can't find anything.

First question:

Do you think there is a reason to install wedges rather than pegs?

Second question:

If I do install wedges, what is the standard for how big, placement, relish etc;.....

Happy 4th of July......

[Brad_bb]

You show a thru tenon.  I've only seen it with pegs.  Now if you had a half dovetail tenon, you'd use a wedge, but I don't think either will hide a shrinkage issue.  Housing a joint will.

[Thehardway]

MM,

In the case of pegs, they were drawbored thru the tie beam and tenon.  In the case of wedges, two mortice were cut on the tongue of the thru tenon below the edge of the tie beam and extending up into the tie beam just enough to allow for the calculated shrinkage. Not sure how clear this description is.  The Ferry Farm Pavillion project of the TF Guild used this arrangement and you can google pictures of it.  When assembled a pair of opposing wedges were driven into each mortice from either side.  They could be tightened as needed.  This joint was also used horizontally in dutch anchor beam joinery and is common in trestle tables.

It does not remove any material from the tie beam, thereby preserving its strength.

You may find some where both pegs and wedges were used.

[mmhailey]

I actually found the thread using the ferry farm pavilion as a search term here on the forum. Thanks Thehardway.

Looking at the checking of the tenon, in the discussion, I think I will just go with the 2 pegs.

Thanks for the input.