Timber Framers Guild Forums General General Forum Questions Hophornbeam for pegs?

I am starting a timber frame project in which I will using woods primarily from my farm. From my reading, locust was often used as peg material. I do not have any locust on the property, although I am sure I can obtain some.

Has anyone used Eastern Hophornbeam for pegs? Not the smooth barked American Hornbeam (or muscle wood), but rather the denser, scaley barked hophornbeam.

Thanks

I used (black) locust for most of my pegs - it makes awesome pegs that hardly ever split. Two to one, better than white oak. When you tap the dry locust pegs against each other, they sound like chalk - that's how hard they are.

I read somewhere in the back issues of the TFG journal that hornbeam makes the strongest pegs. (I think they did some testing and had a chart of the results?) However, I was under the impression that the hornbeam they were referring to is what we call (in Eastern Kentucky) "iron wood" - probably what you are describing as "muscle wood".

So basically, I've skirted around it, but haven't answered your question at all - but I'd be keenly interested if someone _could_ answer your question!

my timberframe project

Both varieties of ironwood are used in tool handles and generally speaking denser is better in pegs.

I believe that's the same report that appears in the green book on page 88. Top of the list is "Hophornbeam (dry)", it's the Eastern Hophornbeam (Ostrya virginiana) that was dried in a microwave. An entry for Hophornbeam (green) falls about 2/3 of the way down the list.

Bear in mind this is a list of single results, the forth strongest peg was Red Oak but the third weakest peg was also Red Oak. They don't have a result for the American Hornbeam (Carpinus caroliniana) aka: Blue Beech, Ironwood & Musclewood.

I'd say you are pretty safe pegging with the Eastern Hophornbeam.

I just found a Forest Service site called the The Center for Wood Anatomy Research that lists shear strength for different woods. Even though Hophornbeam is dense, the shear strength is much less then locust or oak.

The old timers did things for a reason!

i used to mess around with horse logging years ago and ended up using only hornbeam(often called ironwood in my area) for my whippletree. I found it much stronger than oak or ash.... the whippletree is essentially a small beam which has the two tugs(leather lines going to the right and left sides of the horse) on either end and a single line coming off the center to pull the logs. I would also say that hornbeam is also stronger for tool handles, but definitely lacks the feel of ash or hickory. Does this relate to pegs??? I would use it for pegs but oak is so much easier to work with when making pegs by hand or by machine, and there is lots of red oak in my area.

Do they list values for Fb (fiber stress in bending) or MOR (Modulus of Rupture)?

The following was listed on the Center of Wood Anatomy Research site:

Wood/ Shear (lb/sq.in)/ MOR(lb/sq.in)

Hornbeam/ 2410/ 12200

Hophornbeam/ 1790/ 14100

N Red Oak/ 1780/ 14300

White Oak/ 1910/ 15200

Black Locust/ 2480/ 19400

I turn my mallets out of Hop Hornbeam, and they last nearly forever. Oldtimers also called it "lever wood" - it was the first choice for use as chain tightener on log loads.

I bet it would make great pegs.

Pete

Thanks for digging up that chart J.Dean
Looks like I should stick with black locust!

I never tested any of my pegs to failure. OK, there was that time, in vain pursuit of perfection, I tried to rack the frame with my backhoe, and just plain gave up when I heard something pop somewhere - I suspect it was a brace peg, in tension. (but I can't be sure - could've been the relish on the tenon).

What I found really redeeming about black locust pegs was that you can wail on them with a huge mallet, as when driving stubborn (oversized, octagonal, and/or drawbored) pegs. They'll usually rebound from errant off-center hits. Black locust pegs hardly ever split. Dried white oak pegs will split more often under the same abuse. Did I mention - walnut pegs aren't worth a dime?

-Thomas

Ok. So you think you have the perfect peg. Nothing will break it. It will stoutly resist 100 tons in shear. What will your tenon resist? Or the mortise? Is your peg sizing and placement perfectly balanced to optimize the strength characteristics of the joined members.
Lets not get too carried away with one element of the joint if the others are going to fail at 8% of the breakpoint of the strongest element. But it is fun to kick around these topics from time to time! Cheers.