Sitka Spruce - questions

[rmiller3]

I am about to puchase a 2"x8" plank of sitka spruce to build a solid round mast - with widest dimension just in excess of 3".
The plan is to rip the plank down the middle and epoxy the two halves to make a 4x4. I plan to reverse - end for end- one of the planks before laminating.

Questions:
1. What part of the tree, and how to recognize it, should I be looking for when choosing the specific plank?
2. How should this plank have been sawn by the supplier?
3. When flipping one half end for end, should I also turn it over (reversing the grain with respect to the other half in this aspect as well)?

Thanks for any advice.

Robert

[Mrleft8]

Why are you going to flip the board end for end?
If it were me, I'd "book match" it. This way you have the stresses working against each other, creating (hopefully) a straighter spar.
As far as "what part of the tree".... HUH? Sitka Spruce is pretty much all trunk. If you mean the bottom or the top of the tree, I wouldn't worry too much about that. As far as "how the sawyer cut it", I think you'll pretty much get run of the mill stock, unless you want some expensive quarter sawn stock, whic is silly because you're going to make a round spar...

[Steve Miller]

Do you mean sap or heart wood? I'd just look for a plank that is uniform in color. Turn one half over so the grain is opposite and go for it. NOt sure you gain anything turning one end for end but don't see how it would hurt. The fact that the mast is made from laminated wood pieces will tend to keep it straight anyway.

I am just getting ready to do a 16' mast, 2.5" at the base. Probably use Douglas Fir since here in Oregon it is so available.

[Bob Smalser]

http://pic3.picturetrail.com/VOL12/1104763/3075040/40075424.jpg

The stresses in flatsawn wood are for those cupped growth rings to straighten themselves out in seasonal movement.

I'd halve it and laminate with the cups opposed to each other so it looks like a smile and frown atop each other.

[ChuckG]

and you probably know this, but I didn't when I did it wrong the first time: When you glue the halves together, be sure you are clamping them to something that's straight ... smile.gif
-cg

[Bob Cleek]

When laminating a solid spar, there should always be an ODD number of laminations. (Well, at least three, anyway.) In that way, warping and twisting forces will be neutralized. If you glue up two pieces, one will always have a stronger bending/twisting/warping strength than the other and your spar may distort. This also puts a lot of stress on the glue line. On the other hand, if you have three pieces of relatively equal scantlings glued up, the strongest will always have to work against the other two, which in combination will be the stronger and the spar will stay straight.

[Venchka]

Bob's right-I was thinking the same as I read down to his post. Wouldn't 3 1x4's do the trick? Assuming rough cut 4/4 lumber that is really 1" thick. Maybe 5/4x4 or 6. Saves ripping a single 2x8.

Good Luck!

Wayne
In the Swamp. :D