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Re: Laminating deck beams: Spring back

There is a formula for bent lamination springback calculation:

**The basic formula is y=x/n2**

(y is the amount of springback), or the amount x will be reduced after the lamination comes off the mold.

(x is the vertical distance between the chord and the top of an arc in inches, aka camber)

(n is the number of laminations)

(n2 meaning n squared)

If you look at it, you'll note that the largest factor is the # of laminations. If you were making a 2" high beam, and used 1/2" lams, there's be 4. If you were springing it to a 3" camber, your springback would be 3/16"

y = 3/(4*4) = 3/16

If you doubled the # of laminations -

y = 3/(8*8) = 3/64

OR... doubling the # of laminations reduced the springback by a factor of 4

Now... this is a rough formula. The overall length of the beam can play in. The species used can certainly play in. But this'll get you close and give you a sense of how much to expect. Yes... I'd use it to adjust the layout of your forms.

Last edited by David G; 07-14-2022 at 08:52 PM.

David G

Harbor Woodworks

https://www.facebook.com/HarborWoodworks/

"It was a Sunday morning and Goddard gave thanks that there were still places where one could worship in temples not made by human hands." -- L. F. Herreshoff (*The Compleat Cruiser*)