Relative Wood Strength

Re: Relative Wood Strength

Jim DeLaney, Tustin, CA

>Cherry would probably be the strongest of the three. If strength is your primary criteria, why not use hard (sugar) maple?

Actually, any of the woods you've mentioned would probably be sufficiently strong for the job. If the original folding beds were trundled about in ox carts and horse drawn wagons (with minimal suspension systems) and have survived the ordeal, a modern day moving in a station wagon, SUV, or air-ride van should present no problem at all.

Re: Forty Two

William R. Duffield on the Cohansey

>It's not that easy. There are many different properties that get lumped together by the neophyte under the ambiguous characteristic of "strength." It's kind of like "patriotism."

The appropriate wood depends strongly on the types of forces that will be applied to the particular joints and beams of your design, and on the individual tree, and the internal defects, and how the wood was felled and sawn or riven and seasoned, moisture content, wood grain direction, etc.

For a very good tutorial, with formulae, graphs and equations, and measured numbers for common U.S. grown commercial species (which Mahogany is not, of course), refer to Robert Hoadley's Understanding Wood. After studying Chapter 6, Strength of Wood, you might begin to appreciate why Dr. Hoadley has a PhD in this discipline. Additional very useful information, including properties of several different species of mahogany, is provided on-line at the USDA, Forest Service, Forest Products Lab, Center for Wood Anatomy Research.

Personally, I wouldn't use any of these species for that particular project, if I were intending to actually use it on a campaign. In fact, there is not one single species that is best for all the components. However, if you are interesteed in building an historically accurate reproduction, then your only choice is to use the woods that were used in the original, which according to the caption is walnut.

Re: Relative Wood Strength

Michael Stadulis, in Gloucester County, NJ

>John,

You may want to consider osage orange if you can get it. It turns well....is tough as nails ......will darken nicely or can be stained to match the photo, and has decay resistance for the bedpost bottoms.

Re: Forty Two

John Johnston in West TN

>William, thank you for your response. You're right, strength is a multi-faceted concept, and I used it in a general sense. I'll consult Hoadley (I've been waiting for a good reason to get this book!) to learn more about the relative properties of the woods I mentioned (not counting Mahogany). Your post will also be helpful in thinking about some the variables to attend to as I read, and to consider in my choice of wood.

Thank you also for the site information, I'll check that out as well.

While I understand and appreciate that other woods might be better, my interest is in reproduction and use of reproductions. I imagine that combinations of wood might work better, however period craftsmen didn't do that in this case, and the end product worked well. The one example in the photo is walnut, and others exist in cherry and mahogany, so I'll stick to one of those.

Much of the enjoyment of my living history hobby comes from doing it like they did, using the tools, processes and materials that they used. Living with how things work, how they wear, how they last, how they are repaired, is all part of the living history process.

As always William, your help has been most useful.

Thank you,

John

Re: Forty Two

William R. Duffield on the Cohansey

>In that case, I agree that cherry would probably be your best choice, structurally. Consider that George Washington would have had lots of well-disciplined soldiers to transport his furniture, not a bunch of inexperienced, rambunctious Boy Scouts. Also, consider that whoever built the ones that have survived was probably one of the more highly skilled craftsman in the Colonies, would have been an expert at selecting the best wood available for the parts that required critical joints, and had probably already built several of them. Probably a lot of camp beds were built, but not many have survived.

Were you going to make one for camping, Mike's suggestion of Bois d'Arc is well worth considering for structural strength, elasticity and durability. Hedge would not have been readily available during the Revolutionary War. I speculate that it may have been completely unknown to the colonists, since at that time it only grew in the Ozarks.

Re: Relative Wood Strength

William Haun, Forest City, IA

>I would think that this is similar to the Jefferson walking stick/chair that Roy Underhill shows how to make in one of his books. He stresses that the best way to make it is by splitting out the stock. This way, there will be the least amount of grain runout and the wood will be its strongest.

Looks like a fun project to make and use.