Bending wood

From KayakWiki

Bending wood comes in handy in almost all homebuilt kayak methods. For the building of SOF kayaks, it is essential for the forming of ribs. In strip built boats, resistant strips often need some persuasion to get into place.

The ingredient list for bending is

  1. suitable wood
  2. moisture
  3. heat

Most people swear by white oak and ash as great bending woods. In general, hardwoods will bend much better than softwoods. Green hardwood is best; it is pliable and when heated, the moisture in the wood holds heat. Kiln-dried wood tends to bend poorly compared to air-dried.

Heat is generally applied with steam (in a steam box) or with a heat gun. There are those in the know who say that only hardwoods can be bent. Others (Morris) clearly have experience with soft woods as well. It does not matter much whether the wood is flat- or quartersawn. Grain runout will cause more bending problems than grain orientation. The grain must run parallel to the edges of the wood piece being bent.

Some kayak makers advocate soaking wood in water prior to steam bending. However, tests have shown that soaking has no significant effect on the outcome. The only time you would want to soak wood is if you want to preserve green wood - soaking it will prevent it from drying out.

Some of the advantages of bending with a heat gun include

  • not needing to set up a steamer
  • bending or rebending in place
  • not needing to let the part dry
  • complete control of spring back

For an example of the advantages of bending in place with a heat gun, see the page below, where Rick Allnutt needed to reshape all the ribs on an SOF canoe. They had been bent with steam, but were rebent into a different shape with a heat gun while they remained on the gunwales.

http://www.qsl.net/ws8g/canoe.htm

Luthiers use dry heat to bend wood when making instruments - it may be worthwhile searching on the web for information pertaining to that.

There is a book on bending wood by Lon Schleining: The Complete Manual of Wood Bending

Some links about bending wood are below:

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