Inner Wall Skeleton Wood Question

[RunnerDuck]

I'm building my TD walls by cutting and biscuit joining pieces of 1" X to form the skeleton. I bought my wood at Home Depot and it's a pine with some knots.

I thought I'd done a pretty good job of sorting out the wood but now that I'm trying to put it together I find that it's typical "HD" wood that has curves, twists and bows, all though not real bad.

My question is: Since I'll be "skinning" the walls with 1/4" plywood do you think it would be enough to flatten out any wood that's not perfect. I'm worried about transferring any internal flaws to the inside or outside of the walls.

Any thoughts or suggestions? I don't mind buying better wood if I have to but would rather not.

Thanks,

[daveesl77]

WIth mine I used "cull" lumber from HD. Most was 1x8, 1x10 and 1x12, usually in lengths up to about 14'. I then cut them down to 3" widths. Instead of butt joints, I half-lapped all joins. This makes the entire skeleton very, very strong.

Depending on the amount of twist and on the thickness of the skin, you may get away with it just fine. One way to help undo twists, if you have the time, is to take your wood, wet it down (not soaking), cross stack it with separators between the board and with plenty of ventilation between the layers, fair amount of even weight on the top and cover to keep rain out. This is if it is going to be fairly warm and dry where you are at or where your wood is stored. It can take a month, maybe more.

dave

[noseoil]

If you have enough weights or a way to press it flat when the 1/4" is being glued in place, that should help to take some of the warp out of the wood.

Next scenario would be to make the two frames, then stack them on top of each other & (again) weight it down on a flat surface which is good & level. Leave it there a while & see how it looks. Once the 1/4" is glued on one side, it won't be able to move very much. The more weight you can stack on it, the better, as long as the flat surface is strong enough that it's resting on when the glue is setting.

I did my frames out of 3/4" plywood because the 1x material is never really very flat. Plywood tends to be flatter if it's good, but you will be throwing away about 3/4 of the sheet when you cut it out for the webs & edges. If the pine turns out to be junk, find a cabinet shop supplier near you & get some 4/4 poplar which is dry & flat. That will be flat enough & pretty cheap. Home Depot is too expensive & their quality isn't the best on a lot of stuff, especially for dimension lumber.

[dales133]

I assembled my frames directly onto the inner wall skin witch was 6mm ply.
I chose wood as straight as i could get but the bowed bits i used on smaller sections.
Id get a few straight bits for the top and bottom rails and either side of the door tbough,it will save you work down the track
Once my frame was finished i went over it with a straight edge and then belt sanded it true.
Insulated it and belt sanded it before the outter skin went on again.
I belt sanded and or filled the outer skin and it came up perfect.
I had a couple of reasonable bows too but youd never know.
End of the day the strainghtef the timber you use the less work you have infront of you

[Nobody]

I'm pretty sure I wouldn't use any 'bowed' pieces of 1" bys (actual 3/4" thickness) for framework. You're asking quite a lot of the 1/4" ply to straighten a piece of 3/4" wood permanently, especially a short piece. When I built my TD in 2006 (60" outside width, 114" length of cabin overall, 46" high), I bought 1x6" & 1x12" spruce & ripped it to needed widths, discarding any knots, splits, etc. I also had some 1" by white pine from packing crates that I was able to salvage for framework use. Like Dales133 I assembled the framework directly on the 1/4" oak plywood inner wall using Titebond II glue & pocket screws. For the door(s) framing I used oak 1x3" pieces (cut from rough sawn oak boards that I 'ran' thru my small 4" jointer to attain the needed 3/4" thickness). I cut (ripped) my spars from spruce 2x4" (except for the galley hatch hinge connection pieces, again I used solid oak) using notched rabbet joints to attach them to the walls. My TD made its 'maiden voyage' in September 2006 & since then we've towed it more'n 25K miles. The walls are as flat & sturdy now as then, with no problems of any kind I can attribute to wall construction other than occasional 'oil canning' of the aluminum skin on especially hot days in direct sunlight, & that's a temporary thing. After using 3/4" foam insulation in all the 'voids' of the wall framework I 'skinned' the outer walls with 1/8" (I think) luan ply before adding the 0.040" aluminum skin. IMO using good quality framework material is important!

[RunnerDuck]

Thank you everyone for all the great comments. I'll use many of them as I move ahead.

Today I bit the bullet and bought some really nice hemlock that turned out to be quite true. I think it will work great.

The pine boards will become other projects that I'm not so concerned about

Thanks again,