twisted front hatch

Does anyone have some good advice for how to untwist a hatch?  First time build Ches 17LT kit.

I did a dry assembly of my hatches.  The frames are centered and square.  The rear hatch looks pretty good but the front hatch has a funky twist, possibly due to an uneven wood grain pattern in the lower veneer.

I am thinking about flipping it over (frames down) and resting it on a flat 2x4 parallel to the axis of the hatch to get the lower frame edges resting on a flat plane with the squeeze clamps suspended.  I will use a sand bag on top to hold it down in an untwisted position while the glue kicks.

Is there a better way?  How much twist can a hatch have before it allows too much water thorugh?  Will the hatch tie downs fair it a bit when cinched tight?

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RE: twisted front hatch

Something else for you to consider.

Plywood can also twist from changes in humidity.  If your wood moved from one location to another with a different humidity level the outer layers will absorb or expell moisture causing those layers to expand or contract first, causing the twist.    The twist shouldn't be all that great for something as small as a hatch though, unless the change was fairly extreme.  I am building down in Louisiana and the lumber products I have had shipped in curled and cupped when it was unpacked and our "soupy"  air hit it.  I left it laying flat on my build table until it straightened back out.  it took some time, but it did flatten back out pretty good.  

RE: twisted front hatch

If you place the hatch frame side down on an equivalent size piece of 3/4 ply.  shim the frames so they are the right height, and then with glue on the frames and between plies, clamp the edges down you should get a nice non twisted hatch.  The more interesting question is whether the cut out hole is slightly twisted.  The gasket will absorb some mis match but the closer match you get the better.

PS:  I ended up slightly twisted and had to heat the 2 day old hatch to soften the epoxy and reclamp as above to straighten out my hatch which had twisted.

It's not perfect but it keeps the water out. 




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