Managing a large/complicated lamination?

[MushCreek]

I guess 'large' is a relative word here. I'm building a Peregrine 18, and it calls for a laminated frame (just one) in the middle of the boat. The frame consists of 16 pieces to laminate it. I plan to glue it up with epoxy, as ordinary wood glue would probably set up before I could get it all wrangled into position. The good news is that it's symmetrical, so I can clamp it in the middle first. How does one go about bending 16 pieces of wood at once? If you bend one or two at a time, how do you hold the glue-covered wood in place while you grab the next one? I just kind of envision being covered in epoxy from head to toe, with a stream of un-church-like language emanating from the part of my mouth that isn't covered in epoxy. The other option is to glue and clamp a manageable number of plies, let it set, then clean them up and add more pieces the next day. Anyone have any wisdom concerning making this thing?

[stromborg]

There are a few ways to go about this.


I laminated this tiller from 1/8" strips of "green" oak that had been sitting on my lumber rack for a few years so it was really air-dried by the time I needed it. The strips were steamed and bent into a female mold, allowed to dry for a few days then pulled out, slathered with epoxy and put back in the mold. Pre-shaping the strips made it a bit awkward to get the epoxy on but that was made up for in how easily they popped into the form.

How long is the frame going to be? 16 strips means what, 30 faces to wet out? I'd get the slowest hardener I could and cool the shop down as much as possible to slow the reaction time. Maybe find a friend trustworthy enough to get the mixture right so fresh small batches are getting prepared as you get glue on the strips?

[jpatrick]

The first thing you do is put the strips into your bending jig DRY, no glue. Then bend them into the form, apply clamps. This exercise will teach you a great deal and you'll know better how to proceed.

Jeff

[sp_clark]

The first thing you do is put the strips into your bending jig DRY, no glue. Then bend them into the form, apply clamps. This exercise will teach you a great deal and you'll know better how to proceed.

This! Essential preparation for any contemplated laminating endeavor. The dry set-ups show up details that, if left for the last minute when glue’s involved, can ruin both your day and all the work invested.

Give some thought to springback too if you’re not laminating in place, but rather on a form built for the purpose.

I’m hip-deep in an aka-building project: four thicknesses of 5mm marine ply that required scarfing curved workpieces to the required rough 128” length. Once completed it’ll have 2” vertical offset from center to ends built in, and the two center lams will have been hollowed out some prior to glue up. I’m also adding carbon fiber reinforcement between bottom & second lams, where tension forces will develop once it’s complete & in use. Just picked up a nice, dry & straight DF 2x10 12’ long for a ‘strongback’ for the glue-up.

[TerryLL]

The inner stem on my Caledonia Yawl has 8 lams of 3/16 doug fir. The glue-up required a rigid bending form and a ton of clamps. The outer stem has 12 lams of the same thickness and needed even more clamps.

P1010004.JPG.jpeg

You will need to plan all your moves; a practice run without the epoxy will give some idea of all the steps required. Use slow hardener.

[John Meachen]

If its your first big lamination you are right to be concerned.The good news is that it can be done and huge numbers of large laminations have been completed without drama.Preparation is the key and a dry run is a large part of it.If time isn't really pressing it will definitely reduce the stress level if you don't try to do it all at once.The bending form shown in post #5 is a nice looking thing but for a first timer I would add several more arms radiating outwards on both sides so that the laminates have just a tiny amount of wriggle room yet are sufficiently constrained that they can't escape.Allow a bit of extra width for final trimming to the finished size you need.With 16 laminates I wouldn't anticipate any springback at all.

[TerryLL]

MushCreek, what is the thickness and width of the lams you'll be using, and the species of wood?

[MushCreek]

The lams are 1/8" X 3/4" cypress heartwood. The bend is gradual, so they bend easily cold/dry. The finished frame is 46" wide, and the lams are a bit over 6' long. It gets trimmed a lot, so if the ends aren't perfect it's no big deal. One thing I'm worried about is keeping them all on the same plane, but I'm going to have blocks of wood lined with plastic to clamp over them to keep them all in line. Rather than build a separate form, I'm going to mount blocks on the mold frame that's closest in size. Once the lamination is done and cured, I'll remove the blocks so I can use the mold as intended.

I'll definitely do a test run. I also want to be sure that the lams lay as intended over the blocks, and don't want to form gaps.

[TerryLL]

The lams are 1/8" X 3/4" cypress heartwood. The bend is gradual, so they bend easily cold/dry. The finished frame is 46" wide, and the lams are a bit over 6' long. It gets trimmed a lot, so if the ends aren't perfect it's no big deal. One thing I'm worried about is keeping them all on the same plane, but I'm going to have blocks of wood lined with plastic to clamp over them to keep them all in line. Rather than build a separate form, I'm going to mount blocks on the mold frame that's closest in size. Once the lamination is done and cured, I'll remove the blocks so I can use the mold as intended.

I'll definitely do a test run. I also want to be sure that the lams lay as intended over the blocks, and don't want to form gaps.

Sounds like a decent plan. I think I'd opt for a separate bending form. The 1/8" laminations should bend well enough, but 16 of them will require some serious clamping effort. It's quite alright to do the glue-up in two shots, rather than all at once.

Photos will be required. Please.

[rbgarr]

Being in SC I wonder if you couldn't find an arc of live oak to fit that curve. Contact arborists and tree trimming services that manage forests, clear blow downs and roadsides?

[Woxbox]

Can you lay the mold frame down on the floor for this process? If so, put a layer of plastic dropcloth on it and work on top of that. It will then be easy to keep all the lams flat and lined up. Have a mallet handy -- as you tighten the clamps, some pieces might start to work themselves up. Just wack back down and keep on clamping -- but not too much. You don't want to squeeze all the epoxy out of the joint. Also, the cooler the workshop, the better. It will give you more time to work. After it's clamped up, you can turn the heat back on.

[adamarthurryan]

The lams are 1/8" X 3/4" cypress heartwood. The bend is gradual, so they bend easily cold/dry. The finished frame is 46" wide, and the lams are a bit over 6' long. It gets trimmed a lot, so if the ends aren't perfect it's no big deal. One thing I'm worried about is keeping them all on the same plane, but I'm going to have blocks of wood lined with plastic to clamp over them to keep them all in line. Rather than build a separate form, I'm going to mount blocks on the mold frame that's closest in size. Once the lamination is done and cured, I'll remove the blocks so I can use the mold as intended.

I'll definitely do a test run. I also want to be sure that the lams lay as intended over the blocks, and don't want to form gaps.

Sorry if this is obvious, but I'd glue up the laminations a bit over width - ie. with 1" wide strips instead of 3/4". When you're done, you can plane one side roughly flat and trim to the sided width on the table saw. That way the laminations don't have to be exactly coplanar. I did the lamination this way for the center frame of my shellback dinghy. There is a tension between snugging up the laminations to the curve and squishing them down to the plane. For me I squished as much as I could, but some laminations were a near 1/8 " out of plane.

What I wish I'd known then is that a heat gun makes it so so much easier to clean up the epoxy mess.

Also, I didn't know then about using epoxy thickener so I was just using neat epoxy and it was pretty runny as you might imagine. I think I was lucky to not get any voids. The next time I'll use a medium mix - not as thick as I would use for gluing a scarf though. Kind of half way.

I put glue on all the strips first and then bent the whole stack into place together. It was a bit of a struggle, but I don't see how I could add laminations one at a time.

There is going to be a real desire on the part of the strips to go in every direction as you try to bend them, so anything you can do to constrain them from slipping side to side while you're bending them into place will be a help. I think this is your plan, but ideally the laminates will register on one side against the plywood of the mold - ie. the blocks of the mold are set in far enough from the edge of the plywood that the entire depth of the laminate can register against the plywood on one side.

Wear a long-sleeved shirt that buttons up tightly over your gloves. That bit of skin between the gloves and shirt if it is exposed is in my experience a prime place to collect epoxy.

[rgthom]

The stack will be much more slippery when wet with epoxy. I found it helped to drill a hole through the full stack at a place outside the clamp form and hold them together at this one point with a bolt.

[StevenBauer]

I thought this would be about Hewes and company’s bridge/staircase project in NYC: http://www.hewesandcompanyinc.com/marine/epoxyworks/

[John Howland]

I would do a dry clamp first. This way all of your clamps are ready. Side clamping will helped keep every thing in line, set them up as well. I used a anti creeping agent in a urea-formaldehyde glue for vacuum bag glue up. I don't know if there is such a thing for your product but it sure helped with large glue up for me.
I am not suggesting you use a urea-formaldehyde or PVA glue.

[wizbang 13]

ya dont have to lam the slipperry buggerz all at once.

[tri-guy]

One suggestion is that once you are satisfied with your dry fit/trial run, lay out all of your laminates edge-to-edge over plastic sheeting. Apply your epoxy to all of them at once using a roller. After a few minutes flip over all of the laminates except the two outer ones (which will become your inner and outer faces), and repeat on the other side. Then glop on your microfiber mixture or whatever thickening agent you are using and spread it out with a notched plastic trowel. Now you can flop each laminate over one by one to form your 16-piece stack, and carry the whole messy bunch over to your jig. It's faster than trying to brush the epoxy on each strip individually and gives a more even application. Having an organized strategy reduces stress as the clock is ticking.

[MushCreek]

Right now, the shop is pretty cool; it was 50 F. yesterday morning. I want to get this part done before the summer heat kicks in. One idea I though of would be to make the blocks a hair taller than the width of the strips, then put a top piece over it, extending out over the lams. This would create a groove so the lams couldn't shift out of plane very much. The mold I'm going to use isn't mounted to the strongback yet, so I can lay it horizontal at a comfortable working height, and even screw it down to a bench so it's not sliding around as well. This laminated frame finishes at 5/8", so I do have some extra material to work with, but the more even I can get it, the less work later on. It doesn't matter if it comes out a little thicker or thinner than the plans call for. As for the sliding around, I figured I'd put a screw on the centerline, as it's going to be attached to the keelson anyway. The center 8" or so is dead flat, so I'll have a large block there, and a matching clamping caul to keep it flat. Once I get the form made and set up, I'll practice to see how many lams I'm comfortable working with. If I have to do it in several steps, it's not the end of the world.

[timo4352]

Lots of good responses here.
I'll add my two cents...
Take the time and effort to make up a very sturdy mold special made for the purpose.
Having the backer board (covered with packing tape) will help keep the lams in line...you can whack the edges down against the board as you clamp...
Make it a little wider than you need so you can trim it to width.

[MushCreek]

Being in SC I wonder if you couldn't find an arc of live oak to fit that curve. Contact arborists and tree trimming services that manage forests, clear blow downs and roadsides?

Not much live oak up here in the hills. The Blue Ridge mountains are right behind me. It would be a stroke of luck to find a U-shaped piece with just the right dimensions.

[Jim Ledger]

Anyone have any wisdom concerning making this thing?

I've never gained one whit of wisdom from laminating despite having done a few. I could probably come up with a few tips that you might find helpful, however.



Here's an example, the lesson being 'Never do this again". this is a stem lamination, probably thirty-six lams, six inches wide and ten feet long or so. One thing you can take away here is that you don't have to do the whole thing at once; I did this six lams per day, adding onto the existing. 'Nother thing, that's melamine board underneath; give it a coat of paste wax and the glue won't stick to it. The most important thing...it's done on the horizontal onto a male mold.





Here's a frame, Locust glued with Resourcinol. Heavy clamping pressure required here, more than you need with epoxy, much more. Again waxed melamine board underneath. I welded up a set of angle iron brackets because I needed to make about fifty in twenty-five different shapes.





Here's a little mold ready to go. The important thing here is that roll of clear packing tape. I never use plastic sheet because its going to be a pain at the worst time. The face of this mold will be covered with it as will the faces of all the clamping blocks.





This is a breasthook lamination made using a plywood base covered with tape. Locust and epoxy.


ggg


Here's the only good use for wax paper, on top under a clamp pad. I don't do this anymore, though. The block is being glued to the lamination.





This is a lamination using steamed half inch locust lams glued up one or two at a time. That's all the time I've got for now but if you promise me you won't try gluing in the boat first time there's plenty more left in the vault. Good luck and be wise.

[sp_clark]

Yikes Jim that post's a wealth of good info (packing tape's your friend when doing this kinda thing! Sheet plastic doesn't stay flat at the worst times!) and also serves to reinforce the adage you can never have enough clamps!

[SMARTINSEN]

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Do not use Tyvek, epoxy sticks very well.

Use bigger clamps if you can.

Moisture meter is useful in making sure your stock is at an acceptable moisture content.

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Thanks again, Jim Ledger!

This is a dry fit for the second part of a split lamination. 7/16" x 5" white oak. Unglued lam rests in the mold over the weekend. Glue up easier than dry fit.

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[wizbang 13]

ya could do it the simple way and lam em in place. it doan matter if it is the center of the boat or a n end.
here are 5 frames lammed in one lam at a time. AYC, which is actually a cypress ,to fit a diesel in an 80 year old launch.
ya can see how its done, temp screw and a washer
i was helping a friend who likes to wear gloves, so it became far messier than if i'd been alone....gloves pfffft .they get the dookie everywhere





no tape, no waxpaypa,no mold, no blocks,no pre fittin, no steamin,no pre wetting, no notch trowel, no roller ,no yogurt cups
3 knives and a board
days nuttin bafflin bout it, unless you seek perfection
b

[TerryLL]

When laying out your lams, pay particular attention to the grain orientation. Do your best to arrange the lams so the grain direction reverses with every lam. The glue-up will have a much lower tendency to split if the grain reverses with every lam.

Below, the bow stem on my CY. The lams are 3/16 DF.

IMG_0475.jpg

[Seth Wood]

On my current project I've laminated up ten frames with 25-30 layers of 1/8" fir each. By the time I got to the last one I almost knew what I was doing. What I learned that can help you:

1) Yes, you're right to be worried about keeping the stack of slippery lams coplanar. They will want to rise up off the bottom surface, particularly in the sharper curves. You won't see this in a dry test-run and will think all is well. Wrong! The vexing powers of epoxy will make this happen only during the final wet glue-up. You can combat this, as you noted, with a hard block of wood above -- just be sure you have an equally hard and unbendable block below that you can clamp to. I've pulled UP the surface of my workbench before, and now use 1/2" thick scrap steel on top and bottom.

2) I laid all my strips out elsewhere to apply the glue. For me it was MAS 2:1 thickened with enough cell-o-fill to make it a syrup-like consistency: still thin enough to roll on. The key is working fast. Roll on the glue -- ignore the fact that the "down" surfaces will be bare -- and stack the lams up. Before moving to your bending form / clamping area, wrap the whole thing in plastic sheeting and secure closed with painter's tape. This will make an almost magical difference in your ability to hold them all together. Just don't forget to measure and cut the plastic wrap ahead of time so you can stack up the lams ON it. Also ensure the plastic doesn't get pulled into a gluing seam -- thicker plastic will help.

3) It is not possible to have too many clamps. Don't forget to use scrap wood as clamping pads, and don't forget to make the pads narrow enough to fit on the female side of sharp curves.

4) Agree with the above re: gluing up over-thick (so you can plane to the desired thickness in case of any spring-up) and over-length. A huge benefit of gluing a foot or so longer than you need is that when you trim it off later you can evaluate the glue inside. Also agree that you're less likely to see any springback with 16 thin layers.

5) If your time and budget allow, be ready to trash the whole first attempt if something goes wrong. It's always better to abort either during glue-up or after the epoxy cures if something is catastrophically wrong. Getting your head ready for the possibility will make it less horrible if you have to do it. I've thrown out an entire 5' long, 27-layer frame after admitting to myself that I'd mixed the epoxy wrong and it hadn't *quite* set. It happens.

6) If you have any doubt about the glue, your process, or the plastic wrap - top/bottom clamping - managing a long slippery stack of wood process, glue up a couple layers as a test run to fine-tune your trust in your epoxy mixture, where you're storing clamps so you can grab them quickly, etc. Nothing wrong with a practice run which you then saw through to evaluate your gluing, since there are so many variable with the roller, thickener, ambient temperature, clamping pressure, etc.

Remember that laminating, especially if you can finagle alternating growth ring direction on the lams, can result in an extremely strong structure. You will want to look back on this and know you can trust your frame when you get into trouble at sea! Good luck!

[TerryLL]

5) If your time and budget allow, be ready to trash the whole first attempt if something goes wrong. It's always better to abort either during glue-up or after the epoxy cures if something is catastrophically wrong. Getting your head ready for the possibility will make it less horrible if you have to do it. I've thrown out an entire 5' long, 27-layer frame after admitting to myself that I'd mixed the epoxy wrong and it hadn't *quite* set. It happens.

This is great advice. Don't expect everything to go according to plan on your first try.

On my first attempt I used six 1/4" lams. When I released the cured glue-up from the form, the spring-back was way too much. That stem went in the dumpster. Second time around I used eight 3/16" lams, which worked just fine.

[UCanoe_2]

Other more knowledgeable builders have given plenty of good advice. I will only add that in my shop the "Quick-Grip" clamps are nicknamed "Quick-Slip" clamps, because that's what they do.

[AJZimm]

My scar tissue around laminating aligns pretty much with what others have said re: horizontal, dry fit first, trying to keep it co-planar and making the strips wider than necessary and trimming afterward.

The only thing I don't see mentioned (maybe I missed it) is that I prime the laminations with un-thickened epoxy first. I am concerned that some woods are quite porous and potentially will absorb the epoxy out of the mix, weakening the joint. Never worked with cypress so don't know how it behaves in this regard. I use disposable chip brushes to quickly apply the un-thickened epoxy.

[John Howland]

Other more knowledgeable builders have given plenty of good advice. I will only add that in my shop the "Quick-Grip" clamps are nicknamed "Quick-Slip" clamps, because that's what they do.

And they don't have enough clamping pressure for urea-formaldehyde or PVA glue. Hardwoods can need up to 200 psi of clamping pressure for urea-formaldehyde or PVA glueing applications.

Spring back is always an issue if the laminates are thick but not as bad a steam bending. Trial and error is how most learn but there some who have some rules of thumb. If it were easy ever one would be doing it.

[timo4352]

When laying out your lams, pay particular attention to the grain orientation. Do your best to arrange the lams so the grain direction reverses with every lam. The glue-up will have a much lower tendency to split if the grain reverses with every lam.

Below, the bow stem on my CY. The lams are 3/16 DF.

IMG_0475.jpg

Yes. That. for sure. ↑

[John Meachen]

The recommendations in a couple of posts to use plastic sheet beneath the laminates alarm me a bit.Its all too easy for the sheet to wrinkle and get into the glue lines-where it does nothing good.Much safer to use a layer of overlapping strips of parcel tape or to use Jim Ledger's suggestion of melamine faced board to which a little wax has been applied.

[stromborg]

Plastic sheet comes in various weights. Yes the flimsy/floaty stuff can be a problem but thicker sheeting works ok. I like packing tape, cheap and you don't have to store a sheet of melamine though if I were doing a lot of laminating it would be worth setting up a table to do it on.

[akitchen]

My scar tissue around laminating aligns pretty much with what others have said re: horizontal, dry fit first, trying to keep it co-planar and making the strips wider than necessary and trimming afterward.

The only thing I don't see mentioned (maybe I missed it) is that I prime the laminations with un-thickened epoxy first. I am concerned that some woods are quite porous and potentially will absorb the epoxy out of the mix, weakening the joint. Never worked with cypress so don't know how it behaves in this regard. I use disposable chip brushes to quickly apply the un-thickened epoxy.

Yes, i second that. Priming with un-thickened epoxy is a must in my opinion. Another suggestion is to steam or soak the laminations in hot water before the dry run. That will pre-curve them so that you won't have to fight their tendency to straighten when they are slathered in glue. This is helpful if the wood is stiff and resistant to bending.

The photo shows in an inner and outer stem laminated out of sapele. The outer stem had to be laminated in multiple steps because even softened I was unable to pull all the laminations into line at once.

IMG_2089.jpg

[John Howland]

akitchen,

I agree, Steaming and dry clamping will help with spring back. After I had some problems with spring back I started doing that.
I am stilling using urea-formaldehyde glue because what would I do with all though clamps if I started using epoxy.
Good looking stem. Is that for a Catspaw?