Managing a large/complicated lamination?

[Jim Ledger]

That's a lovely model, John. Will it be sailed or is it a display model?

Jim

[akitchen]

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?

Thanks John,

That's a beautiful model. Are you planning to build a full-size version?
The stem is for Siri, an 18 ft canoe yawl by Doug Hylan.

Andrew

[John Howland]

Jim,
Its 1:4 scale. I am gathering up materials now in hopes to build sometime, but not in a hurry. Just got 50 bf of 4 and 6/4 Osage orange last month from my best sawer and been stocking up on clear red cedar, I want to use mahogany on the hull with carvel rolled in cotton seams and slip in a couple regular seams.
I think I may widen a flatten out the aft section to raise the her S#.
I have to say I am inspired by S. Burgess, Herreshoff's and J. Anker and have borrowed heavily from the all.

Andrew
Siri! That is a much different boat, very lovely indeed, are you cold molding her?

I have found my self drawing a lot lately and I haven't gotten a splinter or laceration one.
Building this boat will be a heavy lift so we will see.
Diotima 7.jpg
Here is NIÑA at the Needles 1928
work in process

NiÑA Isle of Wright.jpg

[willin woodworks]

Dry run is a must. And then do another.
Pre bend as much as you can. Steam or boiling water and let everything sit clamped on the mold for a day or two.
You dont have to do it all at once. Do small stacks til you feel confident.
Plastic packing tape on everything, paste wax on the your clamps at the swivel ends. Epoxy has a nasty habit of gluing the swivels to the threads.
Get everything else out of your way. No sense tripping over crap when youre in a hurry and all the lams are slipping around and you knock over the glue and then step in it.

[Arlc]

if a strip has any knots at all discard it. That is where it will splinter.

[MushCreek]

I made my form and did some trial runs. 8 lams are easy to bend in place by hand, so that's what I'll do; 8 at a time. In digging into John Brooks book, I found where he said the Peregrine 18 frame only springs back about 1/8". The outside of it gets trimmed to shape afterward anyway, tapering down to only about an inch at the gunwale. It gets cut to a mold pattern, mounted to the strongback, then further gets trimmed as the planking progresses so that the planks lay on it.

[nedL]

I prefer resorcinol glue. Among other things it cleans up with water.

[John Howland]

I left a roller pan of dried resorcinol / urea formaldehyde resin out side one fall day and left it till spring it snowed rained 0 deg every and I watches it for 5 months or so it never changed it was the same as the first day as the last and it is water clean up.
Kind of tricky because of high clamping presser, a short shelf life, temp sensitive and must be mixed correctly.

[MushCreek]

A couple days ago I did a test with 4 lams and Tite-Bond III, and it was stout. I couldn't get the lams apart without destroying the wood. I might use resorcinal or Weldwood. Both of those are stronger than the wood. The epoxy seems complicated, having to first prime both surfaces with epoxy, then add a thickener and apply that, then put the whole mess together. I have over a hundred clamps here; I'm sure I can clamp it adequately. I've used Weldwood for scarf joints for many years, and never had one fail. Anyone know what kind of glue they use to make marine plywood? We're basically making plywood here, just molded to a shape.

[willin woodworks]

TB111 is my "Go-To". Its great stuff and cleans up with water. I'd use it for your lamination.
Resorcinol is probably stronger but requires perfect joinery, consistently high and well distributed clamping pressure and is very temp sensitive.
The floor of the shop I grew up in was littered with Dixie cups of hardened Weldwood with stir sticks stuck in em...

[MushCreek]

I'm not finding a source for resorcinal glue, other than large quantities. The TBIII is very strong, easy, and cheap (sounds like a girl I dated). The boat is going to be epoxied inside and out, well painted, and live indoors except day trips to the lake. It's not like it's going to be in the water 12 months out of the year. Back in the '70's, I was banging together plywood boats out of exterior plywood and Weldwood Plastic Resin glue, the kind you mix with water. Never had a problem with them coming apart. Earl Brockway was famed far and wide in CT for his skiffs, and that's what he used.

[Woxbox]

TBIII gives you way less time to get the wood coated and clamped than epoxy does. Otherwise, it's very good for lams like this. I've used it on kayak coamings without a problem.

[stromborg]

Amazon has Aerodux Resorcinol available in gallon and quart sized kits.

The great thing about epoxy is how forgiving it is (when thickened at least) of gaps and uneven clamping. MushCreek is right though, with the right preparation and clamping Weldwood ,Tightbond or resorcinol are up to the task of creating bonds stronger than the wood. You also don't have to wait a week or two for the epoxy to finish curing before painting.

[timo4352]

Titebond sets way faster than you want it to in my experience.

[stromborg]

I can't quite justify engineering one for my little shop...

[JimConlin]

Titebond sets way faster than you want it to in my experience.

Some of the PVA glues, like Titebond, creep under sustained load. Not good for bent laminations.

[John Howland]

There are a lot of types of Titebond glues, even a fluorescent one so you can see if you have left any glue on the surface.

[willin woodworks]

Some of the PVA glues, like Titebond, creep under sustained load. Not good for bent laminations.

Based on what experience or research? Some PVA's like Titebond, or Titebond in particular?

[MushCreek]

I doubt that this piece will move. Once it's in the boat, the planking will be fastened and glued to it. I have a line on a good deal on some epoxy, so I'll experiment with that a bit before I tackle the real thing. I'm trying to get as much of the boat parts made as I can, because once I assemble the strongback and start building, my beloved old Miata will be outside for the duration. Once the hull is planked and flipped right side up, then I can move it around to accommodate the car. With the state of lumberyard lumber these days, I'm going to lag bolt the strongback to the concrete floor to keep everything straight.

[wizbang 13]

Epoxy is too complicated
bolt the frame to concrete to save a nickel
good deal on some epoxy
state of lumber these days
smh

[MushCreek]

Save a nickel?? I don't know of a place to buy 2X lumber that will stay put. If you don't fasten it, it will move. I used steel studs in my house for that very reason. If the strongback moves, I'll have a boat that goes in circles.

[jpatrick]

MushCreek, for your small boat you can get by with using 3/4" plywood for the building jig. Ply will require a few more cross braces and legs to the floor, but it will stay straight.

I will be using ply that's glued up in two layers to create 2X material for my jig. Working with straight stock is like taking a vacation.

Jeff

[MushCreek]

The plans call for a surprisingly stout strongback. Two side beams made of 2X8's, and a single center beam of 2X6. Four sets of legs. I thought of using plywood, but at today's prices, the 2X lumber is a bit cheaper. I've been searching the local for-sale sites looking for used lumber, but not finding much. I figured used stuff might have done most of its moving by now. Locally, 2X lumber is generally yellow pine, which can move a LOT. I have a 6X6 in my barn that twisted about 30 degrees, and another one that bowed over an inch. That's KD lumber; I can buy rough sawn, but it's green, and will really move around. It doesn't matter if the pieces aren't perfectly straight, as I can adjust the molds, but I',m worried about it moving during the build.

[stromborg]

I have a few engineered I-joists (left over for building my house) that I plan on repurposing into a strongback for a project down the road. Take a look in the backlot of your local lumberyard, you never know what they might have laying around. Those engineered products start straight and don't seem to move anywhere near as much as 2x timber.

[mick allen]

For long and twisting laminations [curving in differing directions], I used a 'trapping' method first to control the lams as they were wetted out . . . and only then clamped the lams when all together and relatively[!] under control.


in progress, successively removing and replacing the traps on at a time. In this location, the laminations had to twist abt 90 deg thru two 6" trapping forms - juuust made it.

[JimConlin]

I have a few engineered I-joists (left over for building my house) that I plan on repurposing into a strongback for a project down the road. Take a look in the backlot of your local lumberyard, you never know what they might have laying around. Those engineered products start straight and don't seem to move anywhere near as much as 2x timber.

I’ve done a couple of box beam strongbacks of I-beam joists. Longest was 26’. Tops & bottoms were 3/8” ply, 16” wide. They stayed straight even if exposed to the weather for a winter or two. And, they were light enough to move around.

[3sheets]

Some of the PVA glues, like Titebond, creep under sustained load. Not good for bent laminations.

This is real. Don’t use pva for structural laminates. Epoxy, resorcinol, etc with a rigid glue line only.

Other tips:
1. Clamp the center first, and progress outward.
2. Add lots of extra dry laminates to the outside to form the clamping caul. Clamping pressure extends from the clamp at a 45° angle into the material. Make sure the whole thing has clamping pressure.

[MushCreek]

OK, I finally got my epoxy, and laminated 8 of the 16 lams. So far, so good. No pictures, because I would have had to stop, take off the gloves, take a picture, and then resume. I'll post some pics of the aftermath. I tried to minimize the mess as follows-

1) I put painter's tape on the inner and outer lams so there will (hopefully) be less clean-up once I peel the tape off.
2) I laid out 8 strips, making note of which ones had tape (tape side down throughout).
3) Primed one side only.
4) Put thickened epoxy on every other one.
5) Sandwiched them together, wet side to wet side to make 4 sub-assemblies.
I repeated the above to get two sub-assemblies, and then again with the two stacks of four to make 8 altogether.
6) Put the whole mess in the form and clamped it up, including clamping it down against the form to make sure all of the lams are in reasonable alignment.

This method eliminated putting any wet surface down, both to cut down on the mess, and to prevent them from picking up dust. I laid them out on a clean piece of plastic film, but that stuff gets static-y and draws dust like a magnet. The epoxy is kicking nicely (it's in the 80's right now) and I'm going to scrape some of the excess off before it sets up rock hard. Once it cures for a couple days, and I clean up the mess, I'll laminate the other four strips for a finished frame. As a side benefit, I'm getting a good handle on just how much epoxy to mix at a time for when I start planking.

[MushCreek]

Done! I added the remaining 8 lams yesterday, and took it all apart and cleaned it up today. Everything came apart as it should, and no clamps were functionally affected by the epoxy. The rubber grips on the cheap Harbor Freight clamps got a fresh epoxy surface treatment, but it doesn't hurt anything. I had mummified the form with packing tape, so it came out clean. Since any and all lumber is frightfully expensive these days, I set up the #10 mold frame as a temporary laminating jig. It worked fine, and is all set to resume it's role as a mild-mannered building form. Once I removed the laminated frame from the jig, it was an unholy mess of epoxy and random bits of blue painter's tape, but 15 minutes with an 80 grit on the belt sander cleaned it right up. In the picture, I laid it over the full-sized drawing, and it lines up perfectly. I got no spring-back at all. I won't lie; the epoxy is a PITA to mix and spread and deal with, but it sure makes for a hella stout assembly. Clamping the stack of laminates down to the form as well as to the cauls kept the lams in line. I probably took off less than 0.5 mm to clean it up.

[Jim Ledger]

Well done, looks great!

Jim

[jpatrick]

Can't argue with success!

That's quite an assortment of clamps. But I think you could do with a few more. Of course they've all gotta be different!

Jeff

[Canoeyawl]

There are some "big" laminations in Safeway...
(we used to have a forum member that made them like that)

2BB3F6C7-3CCD-4DFF-83EB-C5B85290C9DD.jpg