Timber Framers Guild Forums General General Forum Questions peg placement

See
http://www.tfguild.org/publications/tfec1-07.pdf
section 3.4.8

My quick, lunch time opinion, The tenon would be shortened to 3" deep by 1-1/2" wide, and the 3/4" peg would be centered at 1-1/2" off the edge. This is with no housing. I saw a boring machine on the end of the timber, are you boring mortices with the machine? With a 1" peg I would push it to 2" off the edge/shoulder and lengthen the tenon to 4". But I have switched all minor pegs to 3/4" , pegs that are really holding something together are 1" or 1-1/4".

Tim

thanks Tim. as it is the m&t are cut, with the tenon 6" long. 2" from the edge/shoulder looks as if it should work. i think i'll go with that and go easy on the drawbore.

yes, i used the boring machine for the morticing, and also here for the peg holes (through the mortice at least). love that thing- not boring at all.

thanks for all your help- this is going up after lunch! enjoy yours

can you drill it after you raise it? the weight of the upper structure should push everything tight... no worry of draw bore or splitting.

thanks for the responses, this frame worked out well- still standing!

ok- another peg placement question. this next frame (a 20' covered porch for a ski pavilion) has a 20' 8X8 white pine beam sitting on 3 8X8 posts. the beam is bearing a 6' metal roof over the porch, 5/12 pitch. the braces are 4x6 half lapped dovetail, pegged with 1" pegs. the tenons from the posts into the beam are 2X5, 6" deep.

the question is concerning peg placement. consulting the standards for design manual referred to above, here is what we have:


End Distance-- Edge Distance-- Spacing

Eastern White Pine 4D-- 4D-- 3D

the pegs i have made are 1". 4D edge distance in a 5" tenon doesn't work. 3D spacing also doesn't leave enough room inbetween the 2 pegs i had planned.

how would one make this work? do the pegs need to be pared down to 3/4"?

also, i need to explain this to our structural engineer. i had intended to refer him to the standards manual, but now i wonder.

Half laps can use square pegs and bored at an angle, make them 3/4", tapered square stock, centered on the tenon or favoring toward the shoulder. Why the two pegs?

Tim

thanks for this Tim. would that square pin be angled to be pulled at in tension? is the square profile to tighten it in the round hole? would spikes or metal fasteners be just as well? if the big mechanics of this joint work i don't see much work for that pin, other than to keep the brace in place (vandalism). or is there more to this?

the 2 pegs in the plate is from sobon's "tying joints- tie at plate", page 6. others have only 1. would that be enough? that would be fine then for the 4D spacing to the end of the tenon, 2" from the shoulder, though still short of the 4D edge spacing specified in the standard for design document.

is that 2X5X6 tenon reasonable? it looks like plenty holding the frame together to get it stood up, and i don't see the roof going to kansas.

oooh! those 2 pegs are going into a tie beam- maybe that's the reason for there being 2. we're learning

The angle of the pin is to assist in keeping the half lap from working itself away form the post face, it can't be lifted out if an angled pin is there. If the pin was straight in it could work its way off the peg.

Two of the books I looked at on page 6 were blank pages, which Sobon book are you looking at?

Are these braces tying members or are they in compression.

Tim

thanks again Tim- that makes sense about the pins. other lapped braces have moved a bit on me- that should help.

i was looking at sobon's "historic american joinery" available on this site.

the braces will be largely working in compression, though i like the idea of the dovetail doing work in tension too. so did our structural engineer. it's true that every brace has a buddy opposite, but it's nice to think that each can hold its own in stiffening the frame. also, i find those kind of braces easy to lay out and cut on imperfect timbers, and pretty also- transparent.