White Oak & Laminating

[cs]

What was the final conclussion about laminating white oak?

I've narrowed my choice for rub rails down to 3 types of wood (possibly 4). I'm thinking (listed in order of preference) either white oak, ash, southern yellow pine, or if all else fails Doug Fir.

Reasoning behind choices. Well white oak is the obvious choice, but I'm concerned about laminating it with epoxy for the scarf needed to get the correct length. My second choice is the ash, because it bends real well. Southern Yellow pine cause I can get it real easy (got to check the price though). And if all else fails I'll use Doug Fir because I've used it for rub rails before and it works okay.

I guess the main point of this post is to figure out the best way to laminate a scarf in white oak.

Chad

[Bob Cleek]

The experts say that white oak has the potential for delamination when glued with epoxy. Recorcinol adhesives don't seem to have the same problem with white oak. If you are really worried about delamination you can use recorcinol glue. On the other hand, epoxy shouldn't be any problem. Your rub rail isn't a structural member, so it isn't going to get the stress loads that might contribute to delamination. Moreover, if your scarf is standard length, you will be (or should be) fastening through the scarf to mount the rail. These mechanical fastenings should provide all you need to insure that the glue stays put. Not to worry.

[Dave Fleming]

The 'Cleekster' speaks!

Long time no see Bob.

We return you now to the regularly scheduled topic.

[Nicholas Carey]

Bob Cleek said:
Moreover, if your scarf is standard length, you will be (or should be) fastening through the scarf to mount the rail. These mechanical fastenings should provide all you need to insure that the glue stays put. Not to worry.And you should probably nib the scarf, too, instead of leaving a feather edge. My [lame] attempt at an ASCII art drawing of a nibbed scarf (taper not to scale :D ):</font><blockquote>code:</font><hr /><pre style="font-size:x-small; font-family: fixed;">----------+--------------
|
+
\
\
\
+
|
--------------+----------</pre>[/QUOTE]W/O the feather edge, there's enough meat at the thin end of the scarf to hold a fastener well and it's less likely to tear or abrade at the joint.

[Dave Fleming]

I am partial to the 'Trumphy' style of scarphing.
Envision a lazy "S" on the flat for horizontal scarphs, and on its side for vertical similar to the project in question.
Some call it a 'double dolphin nose' scarph.

Looks very slick for handrail caps out'a Teak or some such.

[ 09-23-2003, 03:25 PM: Message edited by: Dave Fleming ]

[Ian McColgin]

To my mind "laminating" and "scarfing" mean somewhat different things, though one might do both in a particular job.

By laminating, I mean making a thicker stock out of thinner parts. Even though it's not very fat, I laminated Leeward's gunnel as it was easier for me to build to the shape I wanted and then plane a little off than it was to correctly plan all those tapers in three dimensions.

You might laminate your rub rail if you find it too much work to bend the full thickness in one piece.

Scarfing is adding length. This is where 12:1 or whatever comes in.

You might both laminate the rubrail, to gain thickness and keep easy bending, and scarf as the individual laminate layers anre not full length.

If you're not laminating the rub rail at all, you need not bother with epoxy in the scarf either. Just make a nice old fashioned what I call double butt where half the thickness is cut out of each piece allowing them to be brought together with what look like two spaced butt joints, one inside and one outside.

______________________________________________
I______________________
______________________________________I___________

Imagine the I's as verticl cuts.

(Edit - in the draft the I's are in the center as I planned it. You'll just have to imagine the whole piece going off to the left and the verticl cut at the right being where that middle horizontal line ends. I can't do this stuff.)

A fastening near each end and buttered up with SikaFlex or even bedding combound will do you.

I've not had problems with epoxy in scarfing white oak, I think because the end grain gives such a good mechanical hold. Nothing has poped in laminations either and the only precaution I take is an acetone wipe down before painting the glue on.

While I like thin glue lines, I don't actually work to reconsenol standards and I don't 'overclamp' with epoxy. You want some squeeze out but you don't want to put on so much Norweegan Steam that you squeeze the joint dry.

If you're both scarfing and laminating I'd go with simple 8:1 to a feathered edge. Obviously you're not going to worry about pealing off any of the innter layers. I've done such on gunnels that take abuse and even when the feqather edge takes a hard knock, the damage resembles damage anywhere else.

If you're using epoxy, there is one, and only one, excellent reason for putting a bit of square in place of a feathered edge: It's easier to make a visually attractive and small glue line that's verticle to the grain. If you feather the edge, the appearance of the glue line will be 8 times it's actual thickness in an 8:1 scarf. On some woods and under varnish, this is striking.

G'luck.

[ 09-23-2003, 03:44 PM: Message edited by: Ian McColgin ]

[cs]

Think that I will go pick up the white oak tommorow. At $2.01 a board ft is shouldn't be that expensive for what I need.

Ian sorry to confuse you. When I use the lamination I'm referering to glueing, whether it be in a built up section or even just gluing 2 pieces together. I will try and correct my use of the word.

Chad

[cs]

Just got back from picking up some white oak. They ended up selling it to me for $1.875 a board foot. I got what I need for $25 (including tax).

Speaking of white oak how well does it bend? Am I going to have to steam it? Right now the oak is 13/16" thick, do I need to take it down to 1/2"?

Here is what it will be bent around.

http://a2.cpimg.com/image/3C/E0/23259452-57ad-028001E0-.jpg

Chad

[cs]

Bumped up, cause I really need some answers about how white oak bends.

Chad

[Concordia..41]

I think you're going to want to steam it. I recall you've already got a steam box, and it'll make it easier to bend. If you've got any questions, just e-mail. Dave's a regular white oak steaming epoxying machine.

Something he does that I think is clever. He tried scuffing the flaying surfaces with 36 grit, but wasn't satisfied that that was roughing them up enough. What he ended up doing was taking a couple of saw blades from the table saw and putting a dowel through the center.

Sounds bizarre, but with the dowel through the center he can run the teeth of the saw blade back and forth (like a rolling pin) and it roughs up the white oak a lot better than the 36 grit did. Actually the saw teeth make nice little pockets for the epoxy to settle in. Make sense?

And to the epoxy/white oak naysayers we'll report in 20 years down the road, but so far there's not the first sign of failure and we're going on three years since the start of this madness.

[cs]

One of the things that worries me about steaming is this. The oak I was able to get came in 8' lengths, which will put the scarf pretty close to the middle of the boat (which is about the middle of the bend). I'm worried that if I steam it and try to bend it is will make the epoxy pop loose. That is why I was thinking about taking it down to 1/2"

Chad

[Bruce Taylor]

I wouldn't mess w/ steam, in this case.

Scarf the rails w/ epoxy and try them at full thickness, springing them into place with lots of clamps along the sheer. If they absolutely won't take the bend, take them down a sixteenth or so and try again.

Repeat as necessary.

[TimothyB]

Re: Laminating White Oak

The US Navy uses laminated 3/4" or so White Oak for the frames and members for its currently in service wooden minesweeps, built in the 80s. As I recall, you need to use phenol resorcinol glue and heat the glue line to 180 degrees F for 2 hours to insure a bond. They had a heat blower to do this for each frame as they were assembled.

White Oak is the ONLY wood mentioned that needed such treatment. Other woods apparently laminated up fine without heat.

Check the search function on this board. It is what eventually led me to the article about these boats being built.

It is true, based on all reports, that White Oak will not laminate reliably if you don't heat it like this, yes.

--T

[Art Read]

Re: steaming. I'd try it dry first. White oak bends pretty well. I was able to bend my mahogany rubrails, (bullnosed, inch and a quarter by inch and half or so) with no problems at all. Mahogany is usually tougher to bend than oak. Just start at the bow and work your way aft..

[ 10-01-2003, 02:07 PM: Message edited by: Art Read ]

[cs]

I've determined that I will try it dry first like you suggest. I have milled it down to 9/16" thick and still need to run it through the planner and bring it down to 1/2" thick. This should make the bend pretty good and if I need it to be thicker I will just laminate or screw another layer on.

Chad

[imported_Daniel]

cs, I read the article on Doug Schumpert in WB and decided to ask him if he has had any problems with his laminated oak frames. He laminates white oak frames with epoxy. This is the reply I received.

"After steaming into place, the frames are left for a month or two (depending on climate) and then taken down and prepped for glue as follows:

1. A 4" grinder with a 36 grit sanding disc backed by the rubber pad accessory is used to lightly scare up the glueing surfaces to give them some tooth; there should be light scratches enverywhere. (I like to further back up the rubber disc by leaving a used sanding disc in place beneath the new one).

2. Both surfaces are then thoroughly wetted out with West Systems epoxy. Now mix up some more epoxy adding West Systems 403 microfibers to about the consistency of mayonnaise and spread liberally on just one of the pieces. Now clamp in place (not too tightly, just to where the joint closes) and let stand overnight. Next day, dress off the frame with the same little grinder, paint with your favorite poison, and install.

I've used this process for over twenty years, and haven't had a failure yet, even on varnished frames -- be bold, trust it, and it will work."

So there you go, he is very confident in his method.

[Concordia..41]

Ditto - just using the saw blade thing vs. 36 grit.

[ishmael]

Another option would be to not glue it, but bed it well. That thin a stock will take that bend without problem. You know you want the thin edge of the scarf facing aft?

While we're on the subject of rubrails, something often overlooked to the detriment of the appearance, of small boats especially, is a mild taper in the rail both fore and aft. There is little more disconcerting to my eye in a skiff than a clunky piece of stock stuck to the gunwale. Take a little time with it. If you wish you can also make it a little thinner fore and aft, though that isn't near as important visually.