Routing on end grain

[edmund]

is the spline decorative or does it help stabilise such a wide board?

The spline on the shelves is functional (originally I had thought it decorative), but I think it looks quite nice as well. The splines are in the original shelves to help limit movement in the wood (they still look pretty good after 124 years!), which otherwise is unanchored as opposed to a table top.

As I said I have no idea whether this would be appropriate/possible/a complete no no for a jointed 24" top - hence the posts.

Not sure I following waterhead's point about " a 24 inch mismatch in grain direction". If you chop one board into 3 pieces and joint it, surely the grain runs in the same direction - or am I being a bit dim here :?

Also, what's a "breadboard" end?? Some sort of moulding pattern at the end?????

 

[wizer]

http://www.knoxmountain.com/breadboard.htm

seems like a good explanation

 

[Chris Knight]

Edmund,

The mismatch I refer to is the fact of the long grain in the spline glued at right angles to the edge jointed boards in the table top. Seasonal wood movement owing to changes in humidity (and hence moisture content of the wood) can easily cause boards to shrink or expand a quarter of an inch in a two foot width. The exact amount depends on many things including species and the way the boards were sliced from the tree.

The fact that your venerable shelves haven't split is, I suspect largely down to luck, plus a number of other factors that almost certainly will not be reproducible in your proposed top.

You cannot stop wood movement except by keeping humidity constant. All you can do is limit its effects by design of appropriate joinery and the pace at which it occurs, by vapour resistant finishes.

 

[edmund]

I see. Like this http://www.ljoak.co.uk/range/full/Breadboard-Edge-Table.jpg

When would it be vital to use a breadboard as opposed to nothing? E.g. like this http://www.ljoak.co.uk/range/full/Oak-Mackintosh-Table.jpg

Number of boards used for the top? Method of joining top to frame? Both??

 

[edmund]

Seasonal wood movement owing to changes in humidity (and hence moisture content of the wood) can easily cause boards to shrink or expand a quarter of an inch in a two foot width... The fact that your venerable shelves haven't split is, I suspect largely down to luck, plus a number of other factors that almost certainly will not be reproducible in your proposed top.

Sounds like the spline will be a bad idea then. Will the amount of movement of wood depend on how well seasoned it is? I also suppose the advent of modern heating produces a significant effect on movement as well. Does shellac inhibited moisture ingress/egress?

There are 6 venerable shelves which are all flat as pancakes with no splitting or movement at all. The oak for one of the replacement shelves was already starting to cup (think that's the right one) slightly before I finished doing the splines. I'd also guess that the traditional quartersawn wood is more stable than modern quartersawn wood (which I understand is not true quartersawn).

Happy to leave table top unsplined - less work

 

[Chris Knight]

Edmund,

A spline could still be used as long as it wasn't glued along its full length. Were it to be glued at one end say , or in the middle with a glued portion of length less than say 4 inches, you should be OK. However, as noted in the link Wizer provided for breadboard ends, the relative movement is then discernible.

Personally I wouldn't bother at all with a spline. If you alternate the boards forming the top (rings on board ends alternating up and down), then any cupping of individual boards, cancels out to a degree (albeit creating a washboard effect in the extreme).

Quartersawn wood is far more stable than flatsawn stock and will not cup worth a mention, although it's true there is QS and then there is "real QS". The latter is a very wasteful cut and only worth doing on big trees so you won't find it unless you buy the tree and pay to have it cut that way. Still even what passes for QS these days won't cup to any degree.

Not all woods look good quartersawn. Unless it's like oak with medullary rays, it can look very plain. For oak it is the traditional cut for Mission (USA) and Arts and Crafts furniture. Your shelves belong in the latter category although the example you show is not in fact quartersawn.

The quality of wood available to us today is vastly inferior to that that was around 100 or 150 years ago. There is a lovely book called "The Wheelwright's Shop" ( http://tinyurl.com/e2qcs ) that tells how the strength of oak and elm so diminished at the turn of the century, that pieces formerly made of wood, now had to be made of iron.

When you think of how to fix the table top, you must also bear wood movement in mind and not fix the top so that movement across the grain is blocked. Search here and elsewhere for mention of eg "buttons" to help deal with this.

 

[MikeW]

Hi Edmund,

The values in the pic below demonstrate what you can expect White Oak to do, given ideal moisture conditions.

The first line shows what would occur if there was absolutely no change in moisture content within the board. This is a condition which will not occur ever. You can see that a 24" top will not expand nor contract.

The second line shows that if the boards were stablized at 8% moisture in every part of the board(s) (something which also not occur) just a rise of 4% mositure the top would expand a third of an inch in width.

The third line shows the reverse.

fwiw, if I were cutting that slot I would stand the board on end and pass it over the table saw, cutting to one side of center, about 1/3" to 1/2" in depth. Turn the board to put the other face against the fence and make that cut. Flip the board end for end, do both faces again. Raise the blade and do both passes again until final depth on both ends is achieved. This procedure centers the groove on the board and with a full kerf blade gives you a 1/4"+/- groove.

A link to a good site for shrinkage and other calculators is:
http://www.woodbin.com/ref/index.htm
and you'll find the shrinkulator down in the Wood and Lumber section.

 

[MikeW]

Edmund, being in a hurry can have its problems.

To cut something this wide and long, one needs to install a temporary tall (may 1' tall) fence to the existing table saw fence. Feather boards to hold the bottom are also necessary.

Mike

(edited: spelling can be bad when I'm in a hurry, too)

 

[edmund]

Thanks Mike and Chris. The more I learn the more I find out I don't know :-k Will put dunce hat on and do a bit more study this weekend

The Wheelright book looks interesting. Wonder why wood is less strong now. Grows quicker, less mature wood used, climate change, breeding???

Guess one of the shelves started to cup because it wasn't QS - am not going to redo it though. BTW was the first bit of woodwork I've done - last October, so I'm still pretty novice to it all, but certainly know a great deal more than I did then (plus have made my first proper bit of furniture since then).

Onward and upwards

 

[MikeW]

The more I learn the more I find out I don't know. Will put dunce hat on and do a bit more study this weekend.

The more any of us work with wood the more we learn--on every project, just about.

And btw, I would need the full dunce's costume, so don't worry. I'm not certain if any of us get to the top of the learning curve.

Mike
Someone who in his early school years really was set in the corner on a stool and had to wear a dunce's hat. :lol:

 

[Alf]

The Wheelright book looks interesting.

The Village Carpenter being offered with it is good too. :wink:

S'funny, I think I got a lot more made before I found out about all the things that could go wrong... :-k

Cheers, Alf