Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

My father-in-law is about to cut down a large Ash tree (on the insistence of a neighbour). At the same time, we need a dining table, and quite like the idea of a simple wooden slab on legs.

Unfortunately I only have basic knowledge of woodwork, and know almost nothing about seasoning the wood etc. Hopefully there is someone here who knows about this stuff!

There is a local sawmill willing to cut up the tree as required. And I'm able to make the metal legs etc.

What we want to end up with is a thick (about 10cm if possible) chunk of wood for the table top. If this can be done in a solid piece (or 2) then great.

The question is - how to go about this? Should I just ask the sawmill to cut a slab of the required size? Is it better to ask for smaller planks that will together make the required size? Should I leave the top to 'season' after it has been cut? How can I expect the wood to behave as it matures? (I don't mind some cracks and a slightly rustic feel - but not a twisted table top or legs that no longer touch the floor properly).

Lots of questions I know - any advice appreciated!

share|improve this question
add comment

3 Answers 3

Sorry, but I think you may be looking for trouble here. I'm a bit of a perfectionist in my own work, and you may well be willing to accept something more rustic than I'd tolerate. Even so, there are things you will want to do.

This will take some skill to do well, and a lot of time to season that top, and some luck to hope that it does not warp and split too badly. A thick piece of wood will take time to dry until you can be confident that it has stopped moving around. I'd want to give it a year at least, and in a place where both sides will have equal opportunity to lose their moisture at the same rate. Otherwise it will warp or split. Find a spot to store the wood that will avoid it warping under its own weight. For example, if you just stand it against the wall in your garage for a year, next year you will find it bowed under its weight. Worse is if you put it on a pair of sawhorses, as then the bow will be serious. So you might want to store it in a spot where it is supported by wooden stickers every foot to let air in. I might even add stickers on top, then weights on them to try to keep it flat.

And slow drying can be better than a fast dry. So, for example, suppose you put a fan next to the wood, hoping to dry it quickly? A bad idea! This will draw out the moisture near the surface of the wood quickly, but leave the center wet. Splits and checks will form before you can blink an eye. As a wood turner, I've learned to coat the surface of a partially turned bowl completely with wax, letting it dry very slowly over the course of a year. Then you finish turn the warped bowl next year if it has not split or warped too badly.

Dealing with wet wood fresh from a tree is very different from working with wood from a lumber yard, where they were able to dry the wood in stacks in a controlled process. Then you get to select only the wood that is not warped anyway.

Drying the wood can be helped in several ways. First, there are waxy coatings specifically designed to coat things like endgrain. Woodturners use them a lot. This will indeed help reduce end checks. The idea is to prevent the end grain from drying more quickly than the rest of the board, which would then cause end checks.

Another product is also useful, pentacryl. Again, it is available from wood turners supply houses. The idea is it gets into the cells of the wood and keeps them stable in size. It won't be cheap, as you need to completely soak the wood with it. I recall reading that some turners will actually dunk a bowl into a tank of the solution, letting it be completely absorbed into the wood. But it does seem to work from what I've read. (I've never used it though.)

Once it has dried (a moisture meter is a useful tool to test that) then you will need to flatten the top. Some of the tables you see of this kind are made by individuals with access to huge pieces of woodworking equipment, able to flatten very wide boards. If not, then you will use a hand plane and need a good eye for flatness. A long jointer plane is nice for that. (You can buy planes in antique stores, and they are surprisingly inexpensive.) Again, it depends on how the wood has moved after cutting to know what you will need to do.

There are also tricks with dovetailed keys that one can do to deal with any splits, preventing the splits from going any further. In fact, if done artfully, these can be very pretty, the mark of a skilled woodworker at work.

As for the legs, personally, I like the look of a set of wooden trestle table legs. The nice thing here is it actually decreases the probability of the top warping at the corners being a problem. If you have a top held up by posts at the 4 corners, then any warping will be magnified.

Next, consider what you will do at the bark edge if you were planning on leaving it natural. Removing the bark is best, especially since this is where beetles thrive. Ash borers will vacate once the tree is dead, but there are also powder post beetles to consider. Don't bring them inside your house.

Finally, consider how you will finish the top. A thick slab like this should probably have the same finish on top as the bottom, as otherwise you will again have warping issues. Water will enter the pores of the wood, causing it to swell with changes in humidity. (One humid day will not matter. But seasonal changes will cause problems.) A thick top that is sealed on one side will be an issue.

So while I don't want to completely dissuade you on this table, I'd also suggest you do some research into the idea. And don't expect that you will have something to use next week.

share|improve this answer
    
Great information, thanks for taking the time. Yes, it does look like I might be biting off more than I can chew. Perhaps I will try anyway, and risk a failed experiment - I can always use extra firewood ;) –  UpTheCreek May 17 '12 at 11:10
2  
There are always pics in the woodworking mags that show beautiful tables done this way. They have a minimalist look to them that belies the great deal of knowledge of wood and how it moves and works that was employed in their building. The end result is nice though, and the knowledge that you did it yourself is worth the shot. –  user558 May 17 '12 at 11:20
    
@woodchips What about seasoning the log, before cutting it up? Would it be better to let the log lay until it cures naturally, then cut it up into workable pieces? –  Tester101 May 17 '12 at 11:56
1  
@Tester101 - actually, that is a fairly bad idea in general. A whole log will often get a big split, with a crack going all the way to the heart. As the log dries, you will see differential drying rates, with the water leaving through the surface. But the surface of the wood will dry much more quickly than the interior. As it dries, it shrinks, then splits along the line of least resistance (with the grain.) merrimacloghomes.com/shrinkage.htm –  user558 May 17 '12 at 13:36
1  
@Tester101 - another problem with leaving the wood on the ground is decay. While spalted wood is incredibly pretty IF you get it just right (you might like a bowl I've done), spalted wood is also a fungus infested wood that has essentially begun the decay process. The point is, stuff gets into the wood that will start it rotting in a short enough time. So really, it makes sense to slab the wood & remove the bark to reduce the bugs burrowing into it. Put it someplace good to dry and cross your fingers. Cutting the wood also relieves those drying stresses that will turn it into firewood. –  user558 May 17 '12 at 13:43
show 1 more comment

IF you have this sliced, you might want to coat/paint the ends with wax/paint or something to keep it from drying on the ends faster than the center.

A recommendation I remember a LONG time ago was 1 year per inch of thickness to dry a green wood. Best done in the actual location it will be used - or for instance, the basement of the home if it is not damp there (same humidity as the rest of the house).

Allow extra dimensions for shrinkage and working the rough cut down to the working thickness you desire.

My grandfather used to work a good deal of raw tree wood into furniture etc and he had better results letting it dry quite a long time depending on wood species. Putting some good amount of weight on the slab(s) (10cm is pretty thick) with some spacers to allow air flow will help with warp, cupping etc. Try to get extra slabs in case some crack etc. Ask your sawmill operator for advice. DO NOT dry this in the sun.

share|improve this answer
    
Good points here. –  user558 May 17 '12 at 19:07
add comment

If the lumber mill will saw the tree for you, see if they'll dry the boards as well. If not, you will need a cool, dry place to store the planks for a few years(!) - a barn or shed is ideal - and be aware, the planks will warp a bit while they're being seasoned, and will need to be milled flat at the end of it. The wikipedia page on wood drying is insanely thorough, and interesting reading from beginning to end - but here's the section on air drying. (Entire books have been written on the subject of seasoning lumber. They may be worthwhile if you're serious about the endeavor.)

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.