laminating finished dimensional lumber

[dalekidd]

I need to laminate 3 pieces of #1 pine to make my yard for the CIY 16. They are 2,1/8" x 3/4" x 10'. This will give me a 10' blank 2,1/8" x 2,1/4". The surface is very smooth (no paint). Should I rough it up a bit with a quick pass of some coarse grit sandpaper before laminating with thickened epoxy?

[sp_clark]

Can’t hurt, and I’d also ‘prime’ all surfaces to be bonded with unthickened epoxy before applying the thickened mix, then clamp enough but not too much….

[dalekidd]

Can’t hurt, and I’d also ‘prime’ all surfaces to be bonded with unthickened epoxy before applying the thickened mix, then clamp enough but not too much….

That's what I was thinking - can't hurt. Should give the epoxy more bite. Yep, I always "prime". Thanks!

[wizbang 13]

I rough the beejeebus outta lams that are important, like spars.
I'm tawkin dragging a sharp sawzall blade .
I rarely pre coat.For more time to bite, use slower hardener.

[dalekidd]

I rough the beejeebus outta lams that are important, like spars.
I'm tawkin dragging a sharp sawzall blade .
I rarely pre coat.For more time to bite, use slower hardener.

I do use slow hardener not for preference but because I'm SLOW. UGH...

[peb]

I rough the beejeebus outta lams that are important, like spars.
I'm tawkin dragging a sharp sawzall blade .
I rarely pre coat.For more time to bite, use slower hardener.

I suspect this is the best advice. The advice "not to clamp too tight" seems to make sense, but in practice it becomes rather difficult due to the curve one is often making. for many pieces. For spars of course, it makes sense. I do precoat with unthinned epoxy for critical pieces, but typically just rely on 60 grit sand pads to rough them up

[Edward Pearson]

Is the yard shown laminated?

If not i’d build it as shown. The CIY is not short of sail area and is sail and oar beam. If your in higher winds having the end of the spar bend away will auto flatten the sail camber in gusts. Good when solo. This will happen less with a stiffer laminated spar, allthough stiff spars are generally good for sail shape the rest of the time. I’d expect Clint has the spar scantlings down for ‘what works’ so i’d be cautious about possibly changing its bend characteristics without checking with him first.

[dalekidd]

Is the yard shown laminated?

If not i’d build it as shown. The CIY is not short of sail area and is sail and oar beam. If your in higher winds having the end of the spar bend away will auto flatten the sail camber in gusts. Good when solo. This will happen less with a stiffer laminated spar, allthough stiff spars are generally good for sail shape the rest of the time. I’d expect Clint has the spar scantlings down for ‘what works’ so i’d be cautious about possibly changing its bend characteristics without checking with him first.

They are shown laminated. The yard is shown as 2 one inch laminations. I'm going with 3 three quarter inch laminations which I will trim down a bit when shaping. I'm using the lumber that is available to me without breaking the bank. We'll see when performance time comes.

[sp_clark]

Most epoxies formulated for wood have pretty good penetration characteristics and don't need much mechanical 'bite'.

That's the only statement I take exception with in your entire post above, in that he's using 'lumberyard' pine.

That's likely been run thru a planer prior to palleting for shipment. Whether new blades (unlikely) or 'broken in' ones, the resulting surface maybe deserves a close look before glue-up. May look smooth at first glance but may also be too smooth, with many pores closed from being beaten by knife edges.

Softwoods, after a pass through a planer, may not bear optimal condition for gluing, whether with epoxy or anything else. Running a block wrapped with fresh 80 or 100 grit with the grain followed by a proper vacuuming off will enhance pretty much any 'factory' planed softwood surface for gluing.

[Edward Pearson]

Back in the day this was done with a few quick easy bi diagonal passes with a 'toothing plane'....I picked up an old Marples wooden toothing plane off Ebay last year for not much. Beside prep before gluing, you can also use them to deal with difficult grain before a quick smooth over with a superfine set 3 or a 4 'till the tooth marks are gone when smoothing. The cabinet makers toothed high end table tops before laying on and gluing expensive figured veneers back in the day.

This chap shows their versatility...think mine was £20 or so. There aren't people chasing them on Ebay so they're pretty cheap. You'll be the only bidder. Either roughing up of planed surfaces or prep before smoothing highly figured boards like you might pick for the thwarts.

[Edward Pearson]

It'll be OK from a planer. Just don't go mad with the clamping pressure. Better off a saw but if what I was looking at was super shiny smooth and I was gluing up with a fair but of clamping pressure - say a curve, it's just away of avoiding glue starvation from excessive squeeze out by roughing up a bit, pre coating then globbing on some more with epoxy after adding some microfibres +/- a bit of colloidal silica to increase viscosity (and strength) into the pot.

For laminating stems etc, lams off a bandsaw is ideal. You'd really have to go some to squeeze epoxy out and have applied it miserly. I think Bruce said once, you gotta trust it and apply plenty of it, which is true. Epoxy's not cheap but when I unwrap it out of the plastic under the clamps I want to see some squeeze out though. In this case the 2.5 inch or so wide glue line has plenty of area and softwoods glue well. Most people don't own the big G clamps that can really put alot of pressure on.

I actually prefer Resorcinol and use that for tight durable glue lines on backbone structures and spars to be frank. One of it's advantages - it loves a good hard tight clamping (besides UV and fatigue resistance). Not so available in the US and means another pot of goo. Considering all the glued up spars and birdsmouth hobbies, spar failure on small dinghies seems pretty rare. The key to long durability is avoiding penetrating screws and fittings.

One of the best knots to know of is the Icicle hitch. It can hold a tapering spar, on the taper, without letting go. No fitting.

[dalekidd]

... One of the best knots to know of is the Icicle hitch. It can hold a tapering spar, on the taper, without letting go. No fitting.

Haven't heard of that one. I'll look it up. It may come in very hand on my balanced lug rig.

[Stiletto]

One of the best knots to know of is the Icicle hitch. It can hold a tapering spar, on the taper, without letting go. No fitting.

Apologies for the thread drift, that whetted my curiosity, so here you go. .:

[Todd Bradshaw]

On occasion, wood from the lumber yard is not only nearly polished on the surface, but there are times when it even seems like there might be a bit of some sort of waxy stuff on it as well. I don't know squat about the lumber business and what processes they use, but there is no way I would laminate it without giving the surfaces a quick rub-down with a block and some 80 grit before they get epoxy on them.

[David G]

On occasion, wood from the lumber yard is not only nearly polished on the surface, but there are times when it even seems like there might be a bit of some sort of waxy stuff on it as well. I don't know squat about the lumber business and what processes they use, but there is no way I would laminate it without giving the surfaces a quick rub-down with a block and some 80 grit before they get epoxy on them.

This is often the case. It is not at all uncommon for production S4S lumber to come off the planer/moulder with a glaze. Mostly caused by the fact they don't shut down to change out into blades very often. Not the same protocol as hardwood lumber. So the dull blades pound, compress and polish the surfaces. The duller the blades, the more so. And a good finish carpenter will know this, and plan on sanding before finishing. And... sitting/transport can coat the sticks with dust/road grime if they're not stored/shipped wrapped. And contaminants can get on the surfaces.

Same applies to prep for epoxy gluing. If it's fresh off your own planer... no problem. If it's softwood dimensional lumber out of some lumberyard. Scuff it first. Belt Sander or R.O. with #80 is fine. Don't need to go overboard... just scuff it a bit.

And wiz is correct that epoxy will hold up better with a thicker film than with a starved joint. It's the reason I build just the slightest concavity into epoxied scarf joints.

[Edward Pearson]

I found it in Brion Toss' Rigging Handbook (page 55).

[John Meachen]

I wouldn't use bought in wood without ensuring a clean surface and for me,just taking a fine shaving off with a hand plane is all it would get.I have yet to have a joint fail because of an excessively smooth surface but grease,wax,silicone and other contaminants may be present on anything you can't vouch for.Straight off the machine ought to be fine even if the machining ripples tend to leave a slightly thicker glue line than I like to see.

[Sandlapper]

This idea of roughing wooden surfaces prior to gluing seems to get lots of traction. My question is, why? Are there any tests that demonstrate the value of a rough surface over a smooth surface? I don't mean a polished surface but one that is merely machined or sanded. Having been gluing epoxy joints for fifty years without failure attributed to whether the surface is smooth or roughened, I've never seen any benefit to a roughened surface.

Thinking about the close image of epoxy and wood fiber where the epoxy joint surface has been proven to be stringer than the wood itself, I see no advantage to a rough surface. Some joints may vary from this view but a long grain to long grain joint like a spar is not one of them.

Finally looking at all the above answers from some who know and use wood and epoxy regularly, I think the most practical answer is clear.

[DeanP]

The Forest Products Laborabory (FPL) literally wrote the book on the use of wood as an engineering material. You can find it here:

https://www.fpl.fs.fed.us/products/p...00&header_id=p

Chapter 10 of this book (Adhesives with Wood Materials), defines the optimum surface for bonding as a planed surface. There's lots of great info here, but in summary:

"Experience and testing have proven that a smooth, knife-cutsurface is best for bonding. Surfaces made using saws areusually rougher than those made using planers and jointers.However, surfaces sawn with special blades on properly setstraight-line ripsaws are satisfactory for both structural andnonstructural joints. Furniture manufacturers commonly useprecision sawing of wood joints rather than two-step sawing and jointing to reduce costs for labor, equipment, andmaterial. Unless the saws and feed works are well maintained, however, joints made with sawed surfaces will beweaker and less uniform in strength than those made withsharp planer or jointer knives. Dull cutting edges of planeror jointer knives crush and burnish the cells on the woodsurface. Not only are these cells weaker, they also inhibitadhesive wetting and penetration."

[dalekidd]

Thanks for all the input. Lots of good insight and experience here (which we all know). I lightly sanded all the surfaces with some 80 grit and wiped them clean. Tomorrow they'll get glued up: boomkin (routed out), sprit for mizzen, and yard.

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[willin woodworks]

I would never roughen the surfaces prior to gluing with TBIII. The thinner the glue line the better and clamped down like there's no tomorrow. A slick planed surface is optimal.
I would as Todd has pointed out give lumber yard softwood a quick sand to remove the glaze, especially on pine.

[SMARTINSEN]

....The roughened surfaces are good when glues like Titebond or other carpentry glues are used

...
I dd not think this is right.

I would never roughen the surfaces prior to gluing with TBIII. The thinner the glue line the better and clamped down like there's no tomorrow. A slick planed surface is optimal..

I think this is right.

[Sandlapper]

Advice from places like the US Forest Products Laboratory and "Understanding Wood" by Hoadley are trusted sources for information on wood and its uses that can be trusted. Comments by forum members may or may not be worthwhile and should never be taken as gospel. Hoadley's book should be owned by anyone who is serious about getting the best use from their wood as well as the extremely useful material on the effect of shop tools on working wood.

DeanP, thanks for bringing up the USFPL book to this conversation. I often find it indispensable but unfortunately, many boatbuilders don't know of its existence.

[JimConlin]

The West System User Guide https://www.westsystem.com/wp-conten...anual-2015.pdf recommends 80 grit sanding.

[dalekidd]

The West System User Guide https://www.westsystem.com/wp-conten...anual-2015.pdf recommends 80 grit sanding.

Page 28:

"3. Sanded—Sand smooth non-porous surfaces—thoroughly abrade the surface(Figure 8). 80-grit aluminum oxide paper will provide a good texture for the epoxy to“key” into. Be sure the surface to be bonded is solid. Remove any flaking, chalking,blistering, or old coating before sanding. Remove all dust after sanding."

Page 31:

"Porous Woods—No special preparation needed. If surface is burnished, possibly by dullplaner or saw blades, sand with 80-grit paper to open pores. Remove dust."

Not sure whether the wood I'm using is non-porous, burnished or what, but it's awfully smooth. Might be unnecessary, but I still can't see the harm in sanding.

[David G]

Page 28:

"3. Sanded—Sand smooth non-porous surfaces—thoroughly abrade the surface(Figure 8). 80-grit aluminum oxide paper will provide a good texture for the epoxy to“key” into. Be sure the surface to be bonded is solid. Remove any flaking, chalking,blistering, or old coating before sanding. Remove all dust after sanding."

Page 31:

"Porous Woods—No special preparation needed. If surface is burnished, possibly by dullplaner or saw blades, sand with 80-grit paper to open pores. Remove dust."

Not sure whether the wood I'm using is non-porous, burnished or what, but it's awfully smooth. Might be unnecessary, but I still can't see the harm in sanding.

The wood you are using would be classified 'porous'. Sand.

[john welsford]

I need to laminate 3 pieces of #1 pine to make my yard for the CIY 16. They are 2,1/8" x 3/4" x 10'. This will give me a 10' blank 2,1/8" x 2,1/4". The surface is very smooth (no paint). Should I rough it up a bit with a quick pass of some coarse grit sandpaper before laminating with thickened epoxy?

Ok, this is something that has been part of my profession, I was a planer moulder salesman and technician for many years, then for my sins quality control moderator for several gluelam plants ensuring that their testing regimes were being properly carried out, and doing random testing of their samples.

That lumber will have been through a jointed planer matcher, the blades on those are "levelled" with a very soft grindstone on a machine slide so they're all on the same cutting circle, so "rub" as they dont have a clearance angle behind the cutting edge. They tend to polish the surface, closing off the open cells of the wood which is the really nice smooth surface you're seeing.
It doesnt glue well and the joints so made are prone to failure.

The best surface for a high strength glue joint is a freshly cut, planed surface, not a sanded or roughened one, so if its a critical joint I'd freshen the surface with a sharp hand plane, or a cabinet scraper. A sander, about 80 grit, would be the next choice, take all of the shine off the material, both faces.

Note, the giant sanders that finish plywood can do the same, if the grit is getting worn, the sheer horsepower of those machines can still tear the material off but the surface will have been heated enough to cause the lignin to flow and that may close off the cells preventing a good bond. Not common, but it has happened.

John Welsford

[David G]

Porous. Run it thru the planer.

That'd do it.

But there is one potential problem. He wants 2.25" of laminated thickness. He's 2.125" the other way, so I'm guessing he needs to start with a square blank 2.125". If his nominal 1X stock has actually netted out at .75"... then he can afford to lose approx. 0.125" overall in the cleanup. Four faying surfaces. So... about 1/32" off of each. That's some fussy planer work. Easy to take too much. Better to sand w/#80 (more control, less thickness loss). Or, as John mentions, a hand plane or cabinet scraper (also more control, less loss).

And... here comes the curveball. The mills that machine dimensional stock are not geared to high levels of precision. Their market, for the most part is not cabinetmakers doing fine joinery. And so they often fudge a but on the thinner side. It's not at all uncommon to see a net thickness of 11/16"... or 23/32"... for S4S 1X stock. Which means you have to be even MORE careful not to end up too thin on the overall glueup.

Now... he didn't specify, so if what he actually needs is a 2" square starting blank... then all that was just finger exercise.

[dalekidd]

That's exactly what I was thinking David, that he want's to net 2 x 2. Nobody would cut and glue up right at 2.125 if that's what they wanted to net, and the 2.25 is just because that's 3 times .75, but your point is well taken.
Sometimes I assume too much. I know, and that's bad and I'm bad, but I like it that way and it get's the girls.

Plans call for 2" diameter max on the yard tapering to the ends.

[wizbang 13]

Plans call for 2" diameter max on the yard tapering to the ends.

but do plans call for pine ?
we jiggle sizes of things as we jiggle wood species...at least I do

[dalekidd]

but do plans call for pine ?
we jiggle sizes of things as we jiggle wood species...at least I do

Clint uses spruce for his yard in his kits. Not readily available so going to use the pine. I was able to find some Douglas Fir from a bowling alley that was being dismantled but it's 100 miles away and I've run out, used what I bought for my main and mizzen masts. It had fairly tight grain. This pine does not. We'll see how it works. I'm just a poor ol' "neophyte" trying to build a boat on a budget.

[JOBBER]

This may be a "drift" from the topic, and dumb questions.
The original thread stated lumberyard 1x stock, with [3] ply lamination.
Lumberyard stock normally comes with some bow. How are boards orientated for lamination?
The stock is probably plain cut, so growth rings may be present. Is there a preferred orientation for lamination?
Would using a larger width board ripped to desired width(s) be advantageous?
Thanks.

[oznabrag]

Firstly, I think that this thread has gotten a bit out of hand, to the point that we old pharts may be bulldozing a neophyte with TMI.

Secondly, to continue bulldozing, I would like to address the spruce vs. pine debate. Using data from The Encyclopedia of Wood, white spruce is 5% heavier than white pine, has a 6.5% higher modulus of rupture and is 10% stiffer (modulus of elasticity), and is 3% less likely to shear along the grain than white pine. These are pretty small differences.

Finally, dalekidd, go ahead and make your spars out of pine. If you are really worried about the differences between spruce and pine, make your spars 10% greater in diameter - 2-3/16 inches instead of 2 inches. The bottom line is if you build the spar to spec out of pine, and you manage to break it, it won't be the end of the world nor a financial disaster. You will be able to build a new one in a few evenings for maybe $25 - $30 and not likely lose a weekend of sailing because of it.

Our boy there is in Georgia, where White Pine is not very common.

Try the numbers for Yellow Pine.

[dalekidd]

Our boy there is in Georgia, where White Pine is not very common.

Try the numbers for Yellow Pine.

It's not yellow pine. I bought what Lowes call "select pine". It's clear and I believe they label it SPF (spruce, pine, fir).

I've already figured, if it breaks, make another. I don't plan on "pushing" the limits with the rig.

And that hand rail is an idea I'd consider. I used a closet rod on my previous boat for the sprit.

[WI-Tom]

Our boy there is in Georgia, where White Pine is not very common.

Try the numbers for Yellow Pine.

But if he's talking about select pine in big box stores, with not a very tight grain, then I suspect he's talking about NZ-grown radiata pine. Available in up to 12' lengths around here, perfectly clear with absolutely no knots. I build my hull from it. It's very pleasant to work with, and I imagine it's fine for a trailer-sailed boat like mine. Probably the cheapest knot-free wood you can get.

Tom