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Bread Boarding...

Started by Paschale, January 12, 2007, 12:44:29 AM

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Paschale

So I'm in the middle of making an end table from a design in WOOD magazine.  I've decided to use some really wide boards for the top (which is why I've been experimenting with a planer sled).  Now, conventional wisdom these days is to take six inch boards, and then glue them up, with the belief that they'll be much more stable.  I remember asking this question of Kelly Mehler, a guy who's written a great book called The Table Saw.  I asked him about this, and he said it was all hogwash.  I followed up with another question, saying what if you're talking about air dried wood, which is what I'm working with.  He said it didn't matter, and in fact, he only uses air dried wood for his projects.  His attitude was that he wanted to use the biggest boards he could find, because he saw incredible beauty in them. 

Anyway...that's a long way to get to my question.  For those of you more experienced woodworkers out there than I am, would you have serious worries about a 20 in. deep top made from two 10 in. pieces glued together, attached to a carcass?  Would you feel it necessary to add a bread board onto that?  This is an arts and crafts design, and I don't believe there are tons of examples of bread boards, though I'm about to do a Google image search to find out.

I just don't want all the time and energy to be undone by some boards getting outta wack down the road.

What y'all think?
Y'all can pronounce it "puh-SKOLLY"

Ianab

I've done 20"+ tops out of just one board, so 2 x 10" ones should be OK.
More important is to finish both sides the same, if one side is varnished and one isn't then it's going to move, no matter how many boards you have glued it up out of. You dont have to finish the bottom with the same care as the top, but get a similar film there so moisture transfer is the same.
And of course you want the wood properly dry before you build the top.

Cheers

Ian
Weekend warrior, Peterson JP test pilot, Dolmar 7900 and Stihl MS310 saws and  the usual collection of power tools :)

TexasTimbers

I have incorporated bread boards into my chest tops on several occassions. The first I just joined on the edges with biscuits. Purist woodworking says that this is unacceptable, and I know agree. Not because the top failed, it hasn't and it has been 14 years. But the problem is, it has only been 14 years. 24, 34 years down the road will tell the tale.
many woodworkers neglect to remember that going through all the "trouble" to build a familky heirloom dictates thinking in the long term. 14 years is not long term. In hindsight I recognize that now.

The designs that I now use are either a floating dovetail keyway or a mortice and tenon with floating dowels.

The dovetail takes patience as with any worthwhile joinery but is well worht the time and effort. You need to clamp the top vertical and make a jig that will not allow your dovetail bit (or your straight bit w/ m&t), to exert any side to side movement between the two straight edges of your jig. Don't use a single straight edge thnking you can keep the router from drifting it is almost impossible. you need to be working with a thisk top here. 3/4" is acceptable but not ideal because then you are using bits so small that there isn't enough meat for the joint to be effective. Of course a router table or Incra type system is also ideal and makes it tons easier when routing the dovetailed spline portion of the joint, becuase making a jig to do this (trust me on this) can be an excersize in futility although that's how I did it the first time, before I wised up and used my router table.

The mortice and tenon is almost as effective and certainly easier. Just make sure the tenon length is 1/4" or so shorter than the mortice, and that you glue only the middle dowel. The other dowels need to reside in slotted mortices in the tenon, but make sure you don't leave too much space, or too little, between the slot and the dowel so that when the breadboard portion of the top expands and contracts, it doesn't get too losse, or on the other extreme, wreck the joint.

Remember how the wood will expand and contract with respect to the dowel and slotted mortice; the slot is not going to open up very much width wise when you properly orient the grain; that's good. But it will open up lengthwise; that doesn't matter much given proper clearance between the dowel and the slot ends so that too is good. What you want to remember is that the breadboard, and thus the dowel, is going to make it's movement toward and away from the end grain of the top, so the mosr critical element in the design is the placement of the dowel holes in the breadboard with respect to the slot palcement in the tenon.

hope it makes sense I didn't proof read.

Edit: i just did proof read it. ;) I would like to add that I have never actually incorporated either joint in a top as thin as 3/4", because even from the beginning of using a breadboard design in my chests I had thought that 3/4" would be the extreme low end on the thicjness i would want to attempt the design. i suppose I should have said that IMO 3/4" thickness is too thin for these jonts for realistsc long term service life. i have always used 4/4 and thicker for these tops for that purpose and also to minimize even further the cupping/warping out of flat, which is prevelant in big tops - -which is of course the mainpurpose for choosing a breadbaord design in the first place.
The oil is all in Texas, but the dipsticks are in D.C.

SwampDonkey

I use 7/8" planed stock and I've used dovetailing on the last two projects. I use a 1/2" deep x 1/2" wide at the tip of the dove tail bit. Make sure you have good quality bits for the really hard woods. The end grain is easier to dovetail (cuts faster) then the edges of boards. My bread boards are usually done on a wide board and I cut them off with a table saw at 1-1/2 widths, leaving 1/16 or 1/8th extra to run over the jointer to true up the edge. Be careful when slotting ring porous hardwoods though, there isn't much tolerance in the dove tail joint. If it's real tight, you might split it.

As Kevin suggested (I think he did) about gluing, if the boards are long just glue the ends of the bread boarding. I glued the whole length of the table top I made (30 " deep) and it's a struggle when your working against setting time and the glue itself. :D :D

Use as wide a board as you wish as long as it's not a warped board and it's been drying for a long time. Can't see no problem. All my wood is air dried 3 or more years. What I have now is all over 6 years air dried. I like boards 6-10 inches wide as a personal preference, that's all. A lot of my work I have to use stuff smaller than 5 inches wide. ;) Now wait a minute, I ain't in the same league as the New Yankee Workshop guys, but I ain't no Tim Allen neither. ;)
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

TexasTimbers

Best to glue just the center dowel or center of the DT joint so the joint can float so the expansion of the top will not tend to tear things apart. ;)
The oil is all in Texas, but the dipsticks are in D.C.

SwampDonkey

She won't budge. ;D Actually the desk top has shrunk 1/32" over a 31 inch surface. I think it's within tolerances.  ;) Once 4-5 coats of diamond finish is applied she'll never move agin. ;D ;)
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

ohsoloco

Donk, I hope that top doesn't end up splitting on you.  My parents have an old cutting board that has glued breadboard ends on it, and a really nice split down the center of it.  Of course, it was probably finished with oil (long gone) and often wetted and dried with repeated washings. 

I love using breadboard ends on most of the things that I build.  Most of the tops are also only 3/4" thick, and I've never had any problems with them.  One thing I did on my last piece (a coffee table) was to use breadboards that are a little thicker than the actual top, since the seasonal movement will "break" the polyurethane finish anyway, this makes it less noticeable, and adds a little more character to the piece.  Just off the top of my head, I think I made a tenon about 3/8" thick probably 1/2" long along the entire ends of the top, and three longer tenons maybe 1-1/2" long.  I glued the middle tenon only, and just dabbed a little glue on the two outside pegs then they were almost "home" to keep them in place. 

Paschale, I wouldn't be afraid to use two 10" wide boards, I always use the widest boards I can, and I may have to try the planer sled myself so I can use even wider ones. 

I just want to see a pic of the finished table with a fresh hickory nut pie on top  ;)

SwampDonkey

As the old saying goes, 'Ya pay your dime, ya take your chances'. ;D
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

Furby

Quote from: kevjay on January 12, 2007, 05:38:50 PM
Best to glue just the center dowel or center of the DT joint so the joint can float so the expansion of the top will not tend to tear things apart. ;)

Can you explain how that is possible?

sfixx

Gluing only the center of the slot allows the opposing grain directions of the woods to avoid binding. They should have a snug fit along it's length: the dowels for the Mortice and Tendon run vertically through the breadboard, glued to the breadboard end cap but floating in an elongated slot in the tendon. Hope this helps...

Pictures:



Best Wishes,

Steve

Furby

I understand the concept, just not how you ONLY glue the center of a dovetail slot.
At the very least you must glue at least half the length in order to glue the center, or am I missing something?

Almost forgot..... Welcome to the forum Steve!

pigman

I am thinking that on a standard mortise and tendon breadboard it is necessary and possible to glue  only at the center, but on a dovetailed breadboard it would only be possible to glue one end. Sliding that dovetail would spread the glue all along one half of the dovetail. I suppose a person could drill a hole in the underside and try to squirt some glue into the center of the dovetail. smiley_headscratch


Bob- just trying to learn

Gosh, Furby is faster than I am
Things turn out best for people who make the best of how things turn out.

Furby

Sorry Bob.
I guess a few of us are stumped on this.

SwampDonkey

Say I got 5 boards across the width for the desk, I run the first two boards on the end, dab some glue where the third piece comes to and add the last two boards down the dovetail and no glue. Maybe that is what they mean. That would be safe for not so dry wood. I've seen a fellow try to use wood within a year and his stuff splits a lot. Too impatient. If your using air dry wood, ya gotta wait at least 3 years, mines been air drying for at least 6 years.
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

SwampDonkey

I've not only dovetailed and glued the whole length of the dove tails, but I also glued biscuit joints between the boards. Who knows, maybe it will all far apart. This butternut is semi-diffuse porous and soft and I think it can move a lot more than say cherry. It has large pores that are uniform across the grain pretty much. Anyway, time will tell. ;)


"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

sfixx

With a Dovetail you don't use glue, just one dowel in the center inserted from the underside that doesn't penetrate the top. Sorry Furby, I thought that you were asking a more basic question...

Steve

pigman

I just knew I would learn something new. SwampDonkey gave me an idea. Slide the boards on the dovetailed breadboard before gluing them together. Then put a little glue in the center of the dovetail joint before clamping the boards together. 8)


Bob
Things turn out best for people who make the best of how things turn out.

SwampDonkey

Before (flush fit)



After (1/32" movement in one week)



Yes the ruler is graduated in 1/16th's, but it only moved half that. ;)
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

Don K

The only thing I can offer is to alternate growth rings on your wide boards, that way they can oppose each other if they should get into a wrestling match.   ;D
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beenthere

SD
Sorry to see that. Gonna trim it back now, or let it ride it out?
Any idea how much moisture the top lost to shrink that 1/32" ?
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Sprucegum

That much movement can be the difference between summer and winter humidity, or a wet year and a dry. If you shave it back now, next year the end will be too short.

Let'er ride I say.

Furby

Gonna be a real trick if you are bread boarding both ends with a dovetail slot isn't it Bob?
It's not a bad idea, but I know there is no way I could do it.
If one board is off say 1/32" in length, it would mess ya up wouldn't it?

SwampDonkey

I'll touch it up before I apply the finish. At least this time of year the movement is in one direction. When she's sealed with 4 or 5 coats of diamond finish, it won't move significantly. Actually 1/32 isn't much (1/10 %) and butternut does not shrink (Vol %) as much as most other commonly used hardwoods.

Vsh%= V0-V1 x 100
             V0

V0 is initial volume

V1 is final volume or volume at a future measurement
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

SwampDonkey

You can do a 'dry run' Furby, to see how she all fits before committing the glue. ;)
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

pigman

Furby, I was saying it could be done, but I don't think I am good enough woodworker to get it done right. I thing I will just keep using the regular breadboards. I believe in the KISS method. ;D

Bob
Things turn out best for people who make the best of how things turn out.

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