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| Version | User | Scope of changes |
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| Sep 28 2007, 2:40 PM EDT (current) | Anonymous | 396 words added |
| Sep 28 2007, 2:31 PM EDT | Anonymous |
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There are generally two ways to conform wood to a curve. One involves the use of green or air dried lumber and involves the use of a steam box. The temperature, pressure and moisture in the steam box softens the lignin in the wood and makes it temporarily pliable enough to be bent around a form. Traditionally, kiln-dried lumber was exceptionally difficult to steam bend.
The alternative is to create a bent lamination. Lumber is resawn into thin strips and their original order is kept track of, often by simply drawing a cabinet maker's triangle on the edge of the board prior to resawing. The thinner you make the strips the easier they will be to bend, especially around tighter radiuses.
Once you have the resawn strips in hand you need a form. The form can be stack laminations of plywood or MDF which have been faired to your shape, or they can be 'skeleton' forms which provide top, bottom and some middle support. The style of form often depends on the bend being made.
Some craftsman swear by the use of both a male and female form for the bending, others advocate that only one side is required. Here trial and error (basically, experience) will dictate which method works for you and with your bend.
Adhesive choices can also vary, but it is commonly agreed upon that you will need an adhesive that has a rather long open time. The laminations need to be able to slip past eachother when they're conformed around the bend. Yellow glues generally set up so fast that they're not an effective choice here.
As a result of this the more common choice is to use a plastic resin glue. Look elsewhere in this WIKI for a definition and working properties of plastic resin glues.
Finally, you should expect a bit of springback once the laminations are dry and taken out of the form. Because you will generally never know how much springback to expect it is highly recommended that any project requiring a bent lamination have the lam made FIRST. Then use the finished bend as a guage for all of the related components that get attached to it. It's easier to cut flat work to conform to the bend than to hope and pray that the bend comes out to exactly match precut angles made in the flatwork.
The alternative is to create a bent lamination. Lumber is resawn into thin strips and their original order is kept track of, often by simply drawing a cabinet maker's triangle on the edge of the board prior to resawing. The thinner you make the strips the easier they will be to bend, especially around tighter radiuses.
Once you have the resawn strips in hand you need a form. The form can be stack laminations of plywood or MDF which have been faired to your shape, or they can be 'skeleton' forms which provide top, bottom and some middle support. The style of form often depends on the bend being made.
Some craftsman swear by the use of both a male and female form for the bending, others advocate that only one side is required. Here trial and error (basically, experience) will dictate which method works for you and with your bend.
Adhesive choices can also vary, but it is commonly agreed upon that you will need an adhesive that has a rather long open time. The laminations need to be able to slip past eachother when they're conformed around the bend. Yellow glues generally set up so fast that they're not an effective choice here.
As a result of this the more common choice is to use a plastic resin glue. Look elsewhere in this WIKI for a definition and working properties of plastic resin glues.
Finally, you should expect a bit of springback once the laminations are dry and taken out of the form. Because you will generally never know how much springback to expect it is highly recommended that any project requiring a bent lamination have the lam made FIRST. Then use the finished bend as a guage for all of the related components that get attached to it. It's easier to cut flat work to conform to the bend than to hope and pray that the bend comes out to exactly match precut angles made in the flatwork.
