I am making a small table with a lower shelf. The shelf is approximately 16″X15″. I have two mahagony boards which are 9″ wide and can joint them to make the rough blank for the shelf. My concern is about the shelf bowing over time. (the original board was slightly bowed from the lumber yard) I have the board cut 16.5 inches long with the other dimension to be determined after I “glue up” the cut boards. Should I cut the two boards into 4 boards, joining them with the grains in opposite direction to help stabilze the shelf or just join the two boards? Thanks in advance.
Replies
Are you reffering to bow or cup? If cup, then your idea may help, but it's only nine inches and you might be fine without. If bow, on a shelf it's really more a matter of strength than stability. If a shelf sags (bows) over time usually it is overspanned or unersupported/underfastenned and needs reinforcement. Of course you don't want to install as shelf that is sagging to begin with; a slight 'crown' is preferrable. Forgive me if I haven't read your post as carefully as I should have.
Brian
My post was poorly written. I did mean "cupped" not "bowed". You were smart enough to figure out the mistake and answer the question I did not ask but needed an answer to. Aren't woodworkers a smart bunch! Thanks so much
I think the key here is the term "over time"
Being fairly new to all this I am finding that if the wood is acclimated for the space it is to be used in, let it cup or bow, twist etc for a few weeks, months ( in my case years ). Then mill it to near the final dimensions and let it change for a few days. Mill it to final dimensions. Then it will stay the way you have milled it.
The change will come if there is a drastic change such as moving from Florida to Arizona or if you finished one side of the shelf but not the other.
For stability in the drastic change sounds like you will want to go with quarter sawn wood.
I have been observing a couple of slabs of veneer that I have cut off thicker planks. The veneer is ~ 1/4" thick or less and six feet long and eight inches wide. They have bow along the length (not cup) (one in particular ) and I have it placed on two small saw horses in the middle then I have other stuff piled on top of it with popsicle stick "stickers" on the ends but none in the middle to provide pressure/tension to straighten it out. Well after about a year there has been no change. When I remove the stuff on top it instantly goes right back to the original slightly bowed state.
In the photo it looks like I have stickers under the stack between the long veneer pieces but that is an illusion it is just an open gap about six feet ! Stickers are only on the ends.
This is bubinga. Surprisingly strong ! Even with encouragement it doesn't change !
roc
Give me six hours to chop down a tree and I will spend the first four sharpening the axe. Abraham Lincoln ( 54° shaves )
Edited 4/16/2009 7:08 am by roc
Edited 4/16/2009 7:09 am by roc
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