# dealing with bends in a true 2x4 strongback

**URL:** <https://forum.clcboats.com/t/dealing-with-bends-in-a-true-2x4-strongback/35776>\
**Category:** Builder's Forum\
**Created:** [September 17, 2009, 5:16pm UTC](https://forum.clcboats.com/t/dealing-with-bends-in-a-true-2x4-strongback/35776 "2009-09-17T17:16:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Robert\_Evans](https://avatars.discourse-cdn.com/v4/letter/r/9fc29f/32.png) [@Robert\_Evans](https://forum.clcboats.com/u/Robert_Evans)\
**Post date:** [September 17, 2009, 5:16pm UTC](https://forum.clcboats.com/t/dealing-with-bends-in-a-true-2x4-strongback/35776/1 "2009-09-17T17:16:26Z")

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I just built a strongback from rabbetted MDF to 2" x 4". It has couple of little curves to it.

Nick's book is based on a "2x4" strongback and forms that have 2" x 4" holes, so you can true the forms on the strongback by taking advantage of the small difference, and shimming or using cleats. By building a true 2" x 4", I seem to have lost that option. I have no way to move the molds to accomadate the curves.

Did I just screw up the strongback bigtime? If I do it again, might I get it right? Should I try planing the MDF strongback to true (but no longer 2")? Should I toss this MDF strongback and go back to 2x4's, ala Schade?

&nbsp;-Robert

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**Author:** ![J\_Michael\_Berry](https://avatars.discourse-cdn.com/v4/letter/j/ee7513/32.png) [@J\_Michael\_Berry](https://forum.clcboats.com/u/J_Michael_Berry)\
**Post date:** [September 17, 2009, 6:30pm UTC](https://forum.clcboats.com/t/dealing-with-bends-in-a-true-2x4-strongback/35776/2 "2009-09-17T18:30:33Z")

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I had (have) the same problem only I made my 2x4 strongback our of 1/2 inch plywood.&nbsp; I ended up wetting the plywood and leaving it out in the sun on a flat surface.&nbsp; It straighten it out except on the every ends.&nbsp; The strongback was 12 ft long I just didn't think I would ever find a 2x4 (lumber) any better.

I sanded the strongback with my belt sander, rounded the edges to create space for the forms.&nbsp; I had to adjust the end forms, but the other forms lined up very well with just slims.

I read somewhere to use 3/4 inch ply the next time.

&nbsp;

Mike

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**Author:** ![Jack\_Duffy](https://avatars.discourse-cdn.com/v4/letter/j/aeb1de/32.png) [@Jack\_Duffy](https://forum.clcboats.com/u/Jack_Duffy)\
**Post date:** [September 18, 2009, 7:34am UTC](https://forum.clcboats.com/t/dealing-with-bends-in-a-true-2x4-strongback/35776/3 "2009-09-18T07:34:40Z")

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The quality of the materials may be part of the issue.&nbsp; My current project, a dory, required a beefier strongback so I built the box from 3/4" furniture grade plywood.&nbsp; It's very straight but would be too robust for a dainty kayak.&nbsp; I saw&nbsp;a kayak strongback made of 1/2" ply&nbsp;at a local building expo.&nbsp; The builder told me he'd made several 'yaks off the same form with no problems.&nbsp; His was made of Baltic birch ply.