what to look for in white oak?

[cape cod]

When picking out white oak for for bending frames, what characteristics other than it being fresh cut should I look for? I seem to remember reading about grain direction or tightness having an impact when actualy bending the stock. Any advice is greatly appreciated.

Mike

[seayou77]

Hi Mike, Exciting stage of a project! By buying stock to fit the greater dimension you can cut the frame so it has best grain orientation for the bend. You want the arc of the growth ring to land outboard (the concave arc of growth ring inboard). With smaller boats with tight bends, splitting the board along its grain, before cutting out your frames is a good idea.
No knots, especially in a bend. You'll have some break, so buy extra.

[cape cod]

Thanks Seayou 77

If I look at the growth ring as the letter "C" than the open part of the "C" should face inboard?

No knots, and splitting the board along the grain is a good idea.

You're right it is an exciting part of the project and I'm very much looking forward to getting started. Currently I'm stripping paint of the hull so I can get at the screws that secure the old frames.

Mike

[Bruce Hooke]

The absolutely essential first requirement for bending stock is that there be little to no grain runout. I do not bother that much with the orientation of the grain relative to the bend and I have generally been fairly successful with steam bending, but grain runout pretty much guarantees failure...

[rbgarr]

Bruce is correct from my experience. Grain direction matters little, but runout will more likely result in cracks and breaks.

[cape cod]

When you say grain run out do you mean that the grain or growth ring does not span the entire width of the board?

Mike

[Bob Smalser]

http://pic3.picturetrail.com/VOL12/1104763/4518261/56509953.jpg

The board on the right with the chalk line marking the grain direction has grain runout unsuitable for bending stock as cut. Rip such boards using bandsaw along the chalk line followed by jointer and TS to straighten them out.

http://pic3.picturetrail.com/VOL12/1104763/3854395/47481233.jpg

Near a knot you can see the top edge of the board has grain runout but the bottom edge does not. Knotty boards aren't bending stock for that reason.

[ 04-22-2005, 11:08 AM: Message edited by: Bob Smalser ]

[cape cod]

Thank you for the pictures Bob. Unfortuneately being such a novice I'm not sure I see what you mean. Are you saying the grain needs to span the length of the board?

Mike

[ssor]

If you drive a chisel into the end of the board near the edge, if the grain runs out the split you make won't follow the edge but will either break a short piece off the edge or will start accross the width of the board. Try both edges and you don't need to go very deep before you can see the direction the split is taking.

[Nicholas Carey]

Originally posted by cape cod:
Thank you for the pictures Bob. Unfortuneately being such a novice I'm not sure I see what you mean. Are you saying the grain needs to span the length of the board?In the ideal world, yes, on the tension and comression surfaces. It doesn't matter quite as much if there's some grain runout on the side of the frame. But runout, especially on the tension surface is prone to blowouts.

As this useful article (http://www.woodweb.com/knowledge_base/Rx_For_Bending_Wood.html) says:
Anatomy of a Bend
Consider a flat piece of wood 10 in. long and 1 in. thick. As we bend this piece, the outside of the arc will be longer than the inside (Figure 71-2). A flat piece of wood when bent can normally absorb a difference between outside and inside radius of 2 to 3% (without using end pressure or steaming) before breaking. This means a 1-in.-thick piece, 20-in.-long, could be bent on a 24.7 in. radius. The rule of thumb is that the radius cannot be less than 20 to 30 times the wood's thickness without steaming and end pressure.

http://www.woodweb.com/knowledge_base_images/zp/fig71-2.gif

When we steam wood, it becomes more plastic in compression and is, therefore, able to accept more deformation without failure. However, wood does not become much more plastic in tension; the steam only increases plasticity in compression. Returning to the bend in Fugure 71-2 we must understand that the outside radius, which is in tension, is the limiting factor in any bend, even after steaming-although after steaming, the severity of the bends may, in certain cases, be increased without failure.And, in the ideal world, you'd be be taking a fresh, green white oak log and riving it into frame blanks with a froe and mallet or a riving brake:

http://etext.lib.virginia.edu/users/deetz/images/framing15.jpg ("")

See this article, <a href="Riving Wood For 17th Century
Joint Furniture">http://www.greenwoodworking.com/riving/riving.htm</a>. It's about riven wood WRT to furniture making, but the same principles apply WRT to steam-bending.

You want straight, continuous grain in your frame blanks with little to no runout.

[dmede]

Bob, have you (or anyone else here) ever thought of consolidatting your "how to" posts onto a cd for sale to the forum? They'd make great PDF pamphlets.

They are very well thought out and well photographed. Along with the more informative replies that accompany them, they would make a great resource to have all in one place.

I'd pay for it anyway.

dave

[davebrown]

i recall a recent WB article that discusses grain runout relating to planking--different, but analogous.

[kulas44]

This wood bending thing is gettin my mind even more cluttered up. I knew a lot more about it back when I was totally ignorant, or so I thought. I wonder if any of these guys needs an aprentice ?

[ssor]

I think that most of these experienced guys broke a lot of sticks and studied them to see what went wrong. You can learn more from having things go bad than from having everything work without a hitch.
Even the growth rate of the wood affects the quality as far as bending is concerned.

[rbgarr]

Speaking of apprentices, grain runout and planking, I remember a guy who was planking a very full-bowed lapstrake peapod. He had trouble finding cedar stock with enough 'splay' to it to avoid runout of the very curved planks in the bow. He did the best he could and one morning fitted and fastened a plank with the rebate all cut, and went off in his truck to dinner.

An apprentice sat down to eat his sandwich on a sawhorse next to the boat at the bow and gently leaned his head back on the plank. You guessed it... POW! The plank split along the rebate and down to the plank below. Fortunately I saw it happen (and the horrified look in the apprentice's eyes) so could vouch to the builder on his return that it he'd not done anything out of the ordinary. It was probably just as well it broke then anyway. So it goes.

[seayou77]

Are you bending the frames in the boat or on a jig? A collection of shores and wedges? Bar clamps? Are you familiar with strapping the outside of the bend to contain the fibers? A flexy piece of steel, coated w/ duct tape to keep from blackening the wood. Good advice above! smile.gif David

[RiverRat]

WoodenBoat had an excellent article on this and it is worth finding. It explains exactly what you are asking. White oak with knots is better suited for cut framing such as double sawn.

[RonW]

If you are going to build a boat with white oak bent frames. Then you need to know and fully understand grain orientation, flat, vertical, diagonal, grain runout and so forth. Get a book on the subject with pictures, or get some one locally to show and exsplain it to you.

Nicholas Carey's post does a good job of exsplaining splitting green lumber with a fro.

You are not going to get good ribs from sawed and kilned dried lumber. To get premium ribs you need to split them from green white oak.
You need to start with a green white oak log that is a little longer then your ribs that has been quartered. Then split your ribs out and dress them to size on a table saw or bandsaw and plane to exact thickness watching the grain. You want flat grain from one end of the rib to the other end of the rib.

Very few do this and most will pick through sawed lumber trying to get good flat grain and just replace those that break in bending. But that is also the reason you see so many posts on how to replace or sister in new ribs where some have broken over the years.

I am amazed at how many people on the forum don't really understand grain orientation.
It is a lot of extra work, but also is the right and best way to have strong long lasting ribs.
Remember bent ribs are under a lot of tension, where sawed frames are not.

It is just like splitting firewood, but the pieces are a little longer.

[cape cod]

Thank you to all that replied. I'll continue to search for books and articles that explain grain orientation relative to steam bending. If anyone knows the specific issue of Wooden Boat that River Rat referenced in his post please let me know. In respose to Seayou77 the frames will be bent in the boat not on a jig.

I spent the weekend stripping the hull. I now can determine where each screw goes through the hull into the rib. My plan is to remove the screws either by simply unscrewing them or by drilling them. the rib will then be removed and a new steamed rib put in its place.

Because the ribs are so rotted at the turn of the bilge the ribs will lift right off the screws in many cases. I'm now starting to remove the wooden plugs in hopes of revealing a workable screwhead.

Please keep the advice coming because one way or another I'm going to put this boat back together.

Mike

[Bruce Hooke]

While RonW's information on splitting out ribs from logs does probably lay out the absolutely ideal approach, I gotta say, I seriously doubt most professional boatbuilders are taking this approach and the pros seems to be building a lot of good boats. If something is good enough for the pros it ought to be good enough for most of the rest of us. It all depends on how much of a perfectionist you want to be. I'm not saying that RonW's method is bad, just that it is, based on the existing evidence, quite possible to build a good boat without going to that level of perfectionism.

[seayou77]

If you cannot save the frame for any use such as a pattern for bending on a jig, why not split it away from the fastners with a chisel. Take every other one then reframe that station. Come back for the alternate station.
How are the frames entering the boat? Covering boards removed or keelson removed? Back to the oak...would the stock not selected for frames be suitable for floors. David

[cape cod]

Take every other one then reframe that station. Come back for the alternate station.

By this I assume you mean because the rib is not one continuous piece of wood from the starboard gunwhale to the port gunwhale I should do every other frame on one side of the boat and then go to the oposite side of the boat and do the same.

This is exactly what I plan to do.

How are the frames entering the boat? Covering boards removed or keelson removed?

I don't know what you mean by this.

Mike

[Bruce Hooke]

Regarding every other frame...No. What "every other frame" means is if you are trying to replace multiple frames at one time it is OK to go down one side of the boat taking out every other frame on that side of the boat, and then fit and fasten in place the new replacement frames and then go back and replace the frames you do not deal with on the first pass. There is no problem with taking out the matching halves of a frame on each side of a boat at the same time. What you do not want to do is take out two or more adjacent frames on the same side of the boat.

"How are the frames entering the boat? Covering boards removed or keelson removed?" -- What this is getting out is whether you are sliding the frames in from the top (by removing the outermost deck plank) or from the bottom (by removing the keelson). In many frame replacements you have to slither the frames in from the top or the bottom to get them past various remaining obstructions. The easiest situation is where this is not a problem and you can just lay the frames in place.

[RonW]

Bruce, no I am not a perfectionist.
But look at all the posts and pictures with people having problems with grain runout and broken ribs, particularly on something as critical as a bent frame.

The pros don't have time to split ribs, it is too time consuming and labor intensive. But they are ordering lumber from other pros that are in the business of selling marine lumber to pro boatbuilders. And they order vertical grain, flat grain and so forth. And still they have to pick through it and disscard some of it, only still to have a broken rib here and there, which is cheaper to replace it then going through the agony of splitting ribs. The best way.

Most of the people on the board are only part time wood workers trying to build of fix a wooden boat. And a large percentage of them are not totally clear or experienced enough to look at a piece of wood and see where it is going to break when you twist it into a unatural position.

Not only broken ribs, which some have had ribs to break later while they still where building, but also planks splitting due to grain runout.
If more people better understood grain orientation and thought of it just as splitting firewood, they would have fewer problems.

Unless you live on one of the 2 coasts or maybe around the great lakes, getting boatbuilding lumber is tough if not next to impossible. You have to understand grain orientation and pick out your own lumber for the purpose intended.
Or pay one premium price and hope for the best.

And that is why the plywood boat is so popular with back yard boatbuilders.

[Bruce Hooke]

RonW,

You raise some good points. I suppose what I would say is:

1. It would certainly be excellent experience for anyone who is learning to do boatwork to split out some bending stock at some point just to really get a clear idea of how grain works.

2. However, I think the skills necessary to split out good bending stock are as high as, if not higher than, the skills necessary to pick out good bending stock from a pile of pre-cut lumber. In many cases I feel like as a non-pro I have an advantage in stock selection because I can pick through the wood at the lumberyard rather than having to take what comes on the truck. It is easy enough to spec quartersawn or flatsawn and the general grade when ordering lumber, but it is the very rare lumber dealer who will supply specifically selected straight-grained bending stock.

3. In many areas, if finding good boatbuilding lumber is hard, finding good white oak logs will be much harder. For those lucky enough to live in areas where white oak grows and to have property, or friends with property, where they can find and cut a mature white oak tree or two, getting a nice oak log or two should not be too hard. For everyone else it could be a major project!

4. You are right that all of this is an important part of why plywood is so popular! :D Any way you cut it, finding good bending stock takes some time and experience.