Wedged peg Tree Nail or "Trunnel" question?

[Brian Kent]

I posted tonight on the Boat Building forum about a trip to the Great Tall Ship Build "San Salvador" in San Diego. Bruce Heyman gave us far more information than I can digest.

The ship is mostly held together by "trunnels" or "tree nails". I don't remember the main wood for these pegs, but it may have been locust. They use Southern Live Oak for the a lot of the ship's structure, at about 35% moisture. The trunnels are about 5% moisture, of a wood that expends a lot with moisture. They cut a slot, hammer in the trunnel, then use a purple heart wedge. As the Live Oak dries, is both squeezes the trunnel and puts moisture into the trunnel. In the water, the trunnel will expand more, giving a very tight fit.

My question:

I am making an outdoor bench of White Oak, using mortise and tenon, Titebond III, and stainless steel screws to hold her together. As I looked at these trunnels, I thought the wedged pegs might also look very nice. The stainless steel screws would all be hidden, but I would make the wedged pegs visible. If I were to do this, what wood should I use for the pegs (or trunnels)? I would want strength, and a tasteful contrast with the white oak. Instead of using moisture to hold the peg tight, I would use Titebond III and the wedge to hold it tight. The whole bench will be finished with Epiphanes varnish - a couple of coats on the bottom and seven coats on the top.

Thanks.

Brian

[Jay Jolliffe]

Basically it's for looks.....I'd use something that would contrast with the white oak....Something dark as Ipe, Mahogany, teak. That's just me, if I was going to all that time I'd want them to show....

[Sam Murdoch]

Helped build a schooner in the late 70s with oak planking and frames held together with, I believe, locust trunnels. Alas the ship was sunk on its maiden voyage by a captain with book learning but no practical experience - a sad tale :(.

As for your project, I agree with Jay that teak or mahogany would be good. I'd favor the mahogany for contrast and discourage the use of ipe or jatoba as being too gnarly. They would not take kindly to wedgies :).

[Jamie Buxton]

You might use more white oak for the pegs. The end of the pegs will be endgrain, which has a different color from the facegrain it will be glued into. It will be a little more subtle than some high-contrast wood like purple heart.

[Prashun Patel]

I would use mahogany for the peg, and white oak for the wedge.

[Brian Kent]

I normally cut pegs close and then use a low angle block plane. In this case, with 50+ pegs, I would prefer to use a zero-kerf cut-off saw. Are the $10 to $28 cut-off saws by Craftsman Studio / Stanley / Shark / Crown / Irwin / Footprint / Pax / Harbor Freight acceptable for the project?

Thanks

[Prashun Patel]

I use the Irwin Japanese Pull saw. It's versatile and has a flexible blade for getting right up to the wood. Here's the thing: if you get too close, you will scratch the surface with sawteeth. If your pegs are 3/8", you can use an old ROS disc around the peg to stand the blade off slightly.

My point is, I think it's best to cut it a little proud anyway and clean it up to flush, or even leave it proud.

[Sam Murdoch]

Here is a link for such a saw: http://www.japanwoodworker.com/product.asp?s=JapanWoodworker&pf_id=15%2E811%2E5&dept_id=13087

Not cheap & I don't own one, so I can't make a recommendation but this is a good company and not prone to misrepresenting their products.

[David Posey]

If it's a tight fit in the hole, I would use a good sharp chisel just a little bit off the surface and then pare down till you can use the low angle block plane effectively. Approach it from both sides so that you have tearout on one side. I think this would be both faster and easiser than using a saw.

[Brian Kent]

I just ordered the Veritas Flush Cut Double-Edge from Craftsman Studio. The orders usually arrive within 24 hours.

Tonight I will do some tests. I'll try White Oak pegs with Padauk wedges, and Padauk pegs with white Oak wedges. Padauk starts out orange and settles to a nice dark brown. If this doesn't work, I can make a trip to the lumber yard for mahogany.

Thanks.