Based on peg research:

The general rule is the peg needs to be hardwood, straight grained, and of an as-dense or denser species than what you are pegging. Alder is too soft, but I am not too familiar with bigleaf maple. If you check with the "wood handbook" and compare specific gravities of the maple versus the d.fir, you should get an idea if it is ok.

Joe

All the old frames around here that I have seen use the same wood for the pegs as for the frame -- old growth Longleaf Pine (heart pine. It is a great peg wood -- straight grained, tough, strong, stiff, and hard. Today's pine, though, is no more suitable for peg stock than closet rod is.

Also the way some of the pegs are deformed by the draw bore make me think they were driven fairly green.

I agree with Colin. Pegs are not suitable for tension connections and were rarely successfully used for such joints in the past.

Good luck with your pegs Andrew.

Cheers,

Gabel

Andrew

I think you are getting a lot of good advice but if you are looking for a local hardwood we don't have that many choices in the Puget Sound basin.
According to the Forest Service (whose focus is commercially valuable timber) the choices are;
Red Alder
Oregon Ash
Western paper birch
Black cottonwood
Pacific Madrone
Bigleaf maple
Willow

Alder would be my last choice as a building material; it is soft (for a "hardwood") brittle and anything but straight grained. And if used outside it can be called by another common name…compost.

Of the list above my candidates would be Ash, Birch, Madrone (Arbutus for our Canadian buds) and Maple, probably in that order for strength and straight grain. The Ash, Birch and Maple are all species that you should be able to find in the Skagit valley as they are low elevation/river bottom trees.
The Madrone grows closer to salt water, the folk wisdom being that it must smell the salt.
Madrone would be my choice for appearance; it has a beautiful butterscotch color. You do want to work it green, once dry it is very hard.

There is a species of oak in the region, the Gary oak, but this is associated with the south sound prairie ecosystem and is very limited. And for that mater probably endangered in the area

You might also find Black locust which is a none native invasive species with excellent characteristics, one of which is someone will be happy to part with it.

Good luck

J.E.B.

hey guys, thanks a lot. i'm glad to see this topic has generated some interest. right now, i guess i'm leaning towards maple cause i know i can cut one fresh. a friend scored some black locust last spring that they culled out of the state park up here; but i want to try and keep the material close to the same "age." john, have you worked with madrone much? it seems awfully twisty. thanks -ac

Andrew

I have worked with madrone, but I haven’t used it a lot. It does have stability problems but I doubt they would be a factor with pegs.
It occurs to me that it might be prudent and would certainly be interesting to do some experimentation with the different species. You could test for shear and "drivability" (does it shatter when driven)

J.E.B.

Mark, very interesting ideas on the "not so tight joint"! You made a light bulb go on in my timber brain. Thanks. tb