AZ Ironwood Bow

[richgibula]

I have the privilege of obtaining a large piece of Arizona ironwood.  I have previously made a bow out of a piece of mesquite which performs wonderfully, but never ironwood. Does anyone know about the performance of ironwood, like how thick it needs to be (very hard and heavy wood) or how well it will hold together? 

This will be a bit of investment since the wood will be rough on the tools and it is hard to handle due to its weight. I will need to plan a lot.

[BetterTrees]

Well, what do they call ironwood in Arizona. Around here, it's American hornbeam (blue beech).
In the PNW they're talking about ocean spray.
Seems like there's one everywhere. I know whatever the Australian version is was very dense if I recall correctly from my guitar building days.

[richgibula]

This is what I found.  I don't think that its related to beech:

Common Name(s): Desert Ironwood
Scientific Name: Olneya tesota
Distribution: Southwestern United States and Northwestern Mexico
Tree Size: 20-30 ft (6-10 m) tall, 1-2 ft (.3-.6 m) trunk diameter
Average Dried Weight: About 75 lbs/ft3 (1,210 kg/m3)
Specific Gravity (Basic, 12% MC): ~.97, ~1.21
Janka Hardness: 3,260 lbf (14,500 N)
Modulus of Rupture: 10,880 lbf/in2 (75.0 MPa)
Elastic Modulus: No data available
Crushing Strength: No data available
Shrinkage: No data available; reported to be very stable in service

[richgibula]

Workability: Very difficult to work on account of its density. High cutting resistance. Desert Ironwood is usually restricted to very small projects, though it takes a good natural polish and is very stable in service. Turns, polishes, and finishes well.


I just wish I knew something about the use in bows.

Its is considered the 8th most dense wood in the world.

[Kidder]

No experience with it but commenting based on the numbers. It appears to have similar statistics to Ipe but has a comparatively low modulus of rupture - substantially lower than Ipe, Osage, hickory. I would probably consider treating it like Ipe and putting a hard backing on it, but I’d really like to know it’s crushing strength though to be sure about that. But nothing beats practical experience - some woods just surprise in a bow context.

[bassman211]

Use a sharp ax, and rough rasps to get it to floor tiller, and a sharp knife, and sand paper. That works best for me with the blue beech of the east. Make a bow from it . You may end up liking the wood. I wonder how many other woods are going to be called iron wood before to long? Good luck.

[Marc St Louis]

A guy on here made a bow out of some maybe 20 years ago but that's all I remember of that plus it was on another server so you won't find any info on it...I know not much help

P.S. I believe his username was Arquerero

[Hamish]

Amazing that you have found a piece long enough and straight enough for a billet, let alone a full length stave. I've only ever seen photos of AZ ironwood, timber in small craft sections. Most of it is twisty/gnarley, with some clear sections in between, useful for knife handles.

Absolutely beautiful wood, really dense and heavy, looks a lot like cocobolo.

I would second the use of a hickory or boo backing when using wood that is a bit of an unknown quantity. Not all dense woods have the same physical properties in reality, when it comes to bows. Some that look really good on paper can be weak in tension or compression. A backing will stack the odds in your favour

[richgibula]

Thank you everyone for your comments.  I found this piece, about 4" X 6" X 5 ft, at a lumberyard that specializes in mesquite. That's where I got my mesquite for a bow I made.  They inherited the ironwood when they purchased the lumberyard almost 20 years ago. Since then, there has been a ban on new harvesting, according to them.  That has something to do with the fact that ironwood here is a nurse plant for a lot of local plant germination, including saguaro cactuses

There were only a few large pieces and mine has large cracks where I will have to work out where and how to cut ut.  I expect to lose 1 or 2 bandsaw blades in the process. I will likely have to splice two pieces together given the shape and cracks. I am also hoping to do something with the pieces that will remain. If I pair side-by-side pieces, it will probably tiller easier.

[richgibula]

My Ironwood pic.

[Hamish]

More pic's of the billets please?

[Jim Davis]

Take Tim Baker's approach. Cut a small sample from an area that is not going to be part of the bow, thin that piece enough to try some bending experiments. Nearly all woods will fail in compression just before they fail in tension, provided the tension grain is uncut.

Looked at another way, most of a stave is totally wasted in the making of a bow. Where that wood is so beautiful, it's a shame to turn most of it into useless chunks and shavings in order to make a bow that will not perform better than one of Osage or yew.

[TRiggs]

Desert ironwood will split and crack most likely blow up in you face, it makes pretty knife scales that will split if you drop it unless it is stabilized.

[Hamish]

It might be a brittle wood, but the poster is going to back it, so tension won't be an issue. Compression resistance is another matter. It is a risk as some really dense woods don't take compression as well as their density would suggest in theory. eg purpleheart.

I've never really understood the need to stabilize a heavy wood like this, unless it has checked in drying or is knotty. It will sink in water rather than float. This means there is negligible space in the pores, not much empty space for the resin to replace. A medium or light wood will benefit much more in terms of strength by stabilization because all the empty space will be filled.

You sound like you are speaking from actual experience regarding IW, when dropping it. Do you know what method of tang construction was used?
Some woods defintely are brittle when it comes to shock. Nothing beats hickory for an axe, or sledge handle. Several other woods like ash and beech, oak are good too. The thing they all have in common, is that the wood compresses from a missed strike, rather than immediately starting to splinter.

[richgibula]

I have only a beam, no billets.
Thanks for your info.