How dry is dry?

[jalmberg]

I need to laminate some DF to build a new mast holder for my mizzen. A previous owner drilled a hole through the original for a belaying pin, but didn't epoxy or paint the hole. This let water into the wood, yada, yada, yada.

Anyway, it seemed like a simple problem. I went down to my local lumberyard. They have some nice DF. Then stamp on it says 'kiln dried', so why is it so darn heavy and damp to the touch?

The wood is stored indoors in a big shed, so it hasn't been rained on.

I'm just worried that it won't take the epoxy.

Any comments? Suggestions? Am I worrying about nothing?

-- John

[Jim Ledger]

Different grades of lumber get dried to different moisture levels. What's considered dry for a floor joist would be too wet for a stair tread. I believe the magic number for epoxy is 12% MC. If you're looking at framing lumber and it feels wet and heavy, it's too moist.

[Mrleft8]

You're not worrying about nothing. "Kiln Dried" means that it was cooked in a kiln to a specific moisture content (Probably 14% or less). Which in theory kills all sorts of nasty bugs and botanicals. BUT....... That doesn't mean that the lumber is still at 14%. In fact, I think it's very likely that unless it's cabinet grade lumber, it's likely to be well above 20%.
If you want to use D-fir, you'll either need to get some framing lumber, and sticker it inside for a while until it reaches EMC, or buy cabinet grade dry stock.

[jalmberg]

H'mmm... That's what I thought.

I do have a big plank of DF that has been weathering outside for a couple of years in the garden. It's pressure treated, though.

I planed an edge of it last night, just to see what it looked like inside. Once you plane the green surface off, it looks like normal DF.

So, this piece is dry enough, but will the chemicals used to pressure treat it affect the epoxy? I wish I knew more about this sort of thing...

[jalmberg]

Probably not worth the risk using pressure treated stuff... I don't like sawing that stuff, anyway.

I'm going to call around and see if I can find a dry, untreated piece.

[the_gr8t_waldo]

wood used in pressure treated lumber, usually has more knots and wavy grain. i probably wouldn't use it because of the treatment, even if i could find a peice that had acceptable grain.

[Ron Williamson]

It might be dry enough,but feel damp because it's still cold from sitting in the shed all winter.
It might even have some surface condensation from warm air hitting cold lumber.
R

[jalmberg]

Well, I went to a better class of lumber yard and found a nice 2x12 that feels good and dry.

Thanks for the input, guys.

[David G]

jalmberg,

Around here, at least, many of the better lumber yards have moisture meters - and can check a stick for you before you purchase it. In the future, you might inquire.

[john welsford]

The relatively impermeable cellular structure of DF means that the treatment does not go in very far, you can run it through the planer on each side and lose most of it with the outer 3 or 4 mm.

John Welsford

[wizbang 13]

The weight of df is more than just moisture.
Second growth is much heavier than old growth.
Some fir is heavy like iroko, some is almost light as spruce.

[jalmberg]

Well, I hope they aren't cutting down virgin DF forests and shipping them to east coast lumber yards

This is the heavy stuff. A moisture meter would be a good idea. I'll have to ask, next time. But this seemed dry enough. The glue is setting right now, so I'll have a better idea tomorrow, but I think it will be okay. Time will tell, I guess.

I'm thinking of buying some long, 12" DF stock and stickering it up for a while. I need to replace my bowsprit one of these days. Might be a good investment to have some dry stock on hand? The current one was laminated from DF, as was most of the boat, I think, except for the ribs.

[Mrleft8]

I'd look for old growth or very slow growth Eastern White Pine for your sprit.
Strong, light, flexible, but not floppy, takes varnish and paint very well.

[purri]

"Kiln dried" can easily case harden a timber and you bear the results.

[Bob Smalser]

Why guess and risk a failed lamination? A good moisture meter can be had between 65 and a hundred bucks.

http://www.amazon.com/Lignomat-MINI-...399429&sr=1-48

http://www.amazon.com/Extech-MO100-M...399429&sr=1-40

And structural and exterior trim wood is generally kilned to a heat standard, not a moisture content standard, but you'll find it runs just below 20% MC, which is still too wet to glue.

[jalmberg]

Another excellent suggestion, Bob. I definitely owe you the cold or hot beverage of your choice, if I ever make it out to the west coast.

I'd never have thought they were so cheap. Thanks!

So how dry does wood have to be to laminate? Does it vary by species, or is there a general rule for all wood?

[jalmberg]

H'mmm... You guys got me thinking. Since this is such a small piece (roughly 18"x8"), the strips of wood would easily fit in the kitchen oven. Anyone every tried drying wood in an oven? At a very low temp, of course?

I seem to recall reading somewhere that measuring the weight of a piece of wood and drying it in an oven until it stops losing weight is another way to figure out the moisture content, so surely an oven would take the water out, but would it damage the wood too much?

[Mrleft8]

Oven drying works. It's nice if you have a convection oven to really get the air moving around.... But..... It's 8"X18"x?....... Maybe I have a piece already dry that I could send to you, so your wife doesn't wonder why her next cake tastes like sawdust?...

[Ron Williamson]

I've done small bits in the microwave.
Filled it with pine smoke,too.
If you keep an eye on it,with the oven set at 150-180,you will have a hard time doing any real damage.
'Until it stops losing weight' is difficult unless you have an accurate scale.
Carefully measuring the width and cup, before and after,is a pretty good exercise,as well.
R

[jalmberg]

My wife is in Brazil at the moment, visiting her family, so it's the perfect time to experiment

Yes, 18x8, but 1 3/4" thick, which is why I have to laminate it to get the right size. I need to replace the mast step that I had to cut/chisel off:




It's going to be a real pain to get it to mate to the remnant, but once I have the new piece roughed out with holes drilled, I think I can shape the remnant to fit the new (flat edged) piece with a chisel and a whole lot of time.

The remnant is epoxied to the transom and VERY awkwardly placed under the rail and over the stringer, so it's impossible to remove it completely. Well, maybe not impossible, but cutting it off where I did was difficult enough, with those 4 rods.

[Mrleft8]

Ah..... I see your dilemma.....
I would consider using a sandwich laminated out of 3-5 layers of opposing grain lumber so that the whole issue of splitting along the grain is eliminated... Basically making your own plywood, but make it out of better material.
Certainly several layers of Mahogany would do a good job...... BUT Even if you decide to stay with solid wood, I suggest putting a thin layer of opposing grain wood underneath the visible part with screws so that you essentially have a cross grain cleat. It shouldn't cause expansion/contraction issues at that dimension, and screws do allow for a certain amount of wiggle room. That's what I did with my Catspaw mast partner.

[Mrleft8]

Is there no way to knock those rods back into the under deck area so that you can make a good glue joint?

[jalmberg]

Is there no way to knock those rods back into the under deck area so that you can make a good glue joint?

I can't knock them back, the original builder put epoxy in the holes, so the threads are biting on epoxy. I suppose I might be able to put a pair of vice grips on them and twist them out... Not a bad idea. Just have to avoid ruining the threads, somehow. I will give that a try this afternoon. Thanks!

[Mrleft8]

They can always be replaced. Sometimes it's cheaper to replace than try to salvage. If you bung up the threads you could try re cutting them with a die, but knocking them back, and replacing them with bolts and fender washers might be faster, easier, stronger, and a lot less frustrating in the long run.

[jalmberg]

Ah..... I see your dilemma.....
I would consider using a sandwich laminated out of 3-5 layers of opposing grain lumber so that the whole issue of splitting along the grain is eliminated... Basically making your own plywood, but make it out of better material.
Certainly several layers of Mahogany would do a good job...... BUT Even if you decide to stay with solid wood, I suggest putting a thin layer of opposing grain wood underneath the visible part with screws so that you essentially have a cross grain cleat. It shouldn't cause expansion/contraction issues at that dimension, and screws do allow for a certain amount of wiggle room. That's what I did with my Catspaw mast partner.

I selected the DF so that the grain would be in the right direction. I'm pretty sure the original was DF, and between the thickness of the wood and those 4 steel rods, it's insanely strong. Even half-rotted away it was strong enough to hold up the mizzen. There is a steel plate that goes on the outside of the wood, so really the mast is held up with steel, and the wood is only a spacer. The whole thing is overbuilt, much like the rest of the boat.

Even if it delaminates, the rod and steel strap would hold it together.

[jalmberg]

I wish I'd taken a good 'before' picture. Here are some accidental shots. Both of these pictures were taken on the west coast of Florida, and you can see from the second one that the rot was showing through the paint. However, it was still plenty strong enough to hold up the mizzen.

Like my kerosene anchor light? It was plenty bright enough for the west coast of Florida, where it's pretty wild, but I had to replace it with a bright electric light on the east coast, where there was a lot more background light at night. The kerosene flame was lost against the background light and I almost got run down one night. Good times!

[Mrleft8]

Ah.... OK.... Then I think I might be tempted to just epoxy in a piece of well sealed lumber, and get a piece of stainless plate that could go underneath (or even on top) to do the actual work.

[SeaB]

You said the bolts were set in epoxy, how about making the epoxy nice and soft by heating the bolts with a propane torch?
Then tap them out, through the softened epoxy.

[Bob Smalser]

To use available construction lumber @19% MC without ruining it trying to dry it too fast...(ask yourself if it passes the common-sense test that you're gonna do in a few minutes in the microwave what it takes a real kiln 10 days to do)...simply use a glue engineered specifically for construction lumber @19%. Namely, a moisture-curing polyurethane construction adhesive.

PL Premium available at the box stores is one of the better ones. No worries with this specific application because it's the bolts doing the work, not the glue.

[jalmberg]

To use available construction lumber @19% MC without ruining it trying to dry it too fast...(ask yourself if it passes the common-sense test that you're gonna do in a few minutes in the microwave what it takes a real kiln 10 days to do)...simply use a glue engineered specifically for construction lumber @19%. Namely, a moisture-curing polyurethane construction adhesive.

PL Premium available at the box stores is one of the better ones. No worries with this specific application because it's the bolts doing the work, not the glue.

Another handy tool added to my box of tricks. Thanks.

[Bill Perkins]

If you choose to add a piece : getting max separation between the mast step and the partners (the latter set tight up to the bottom of the rail cap ) would place less stress on the installation and the mast if the staying is less than perfect at any time in the future.

[wizbang 13]

If you choose to add a piece : getting max separation between the mast step and the partner (the latter set tight up to the rail cap ) would place less stress on the installation and the mast if the staying is less than perfect at any time in the future.

Yea, I'd move the partner up on the rail. And double saw and glue it .