Dry 165 yr old tree slabs

[Stumper]

Recently, received (2) 40 inch wooden rounds (perp. cuts thru a tree trunk). I would like to work these into table tops, but I am not a wood craftsman. As a result, I'm turning to the group for guidance and advice.

The Story is that some 30 years ago, a 165 year old tree was killed by a steampipe break. As the men started to cut down this mighty white oak, my father had them cut him some 4 inch thick slabs. Once safely in our garage, he periordically poured ethylene glycol over the slabs - I can still remember the smell and sight of this process as a kid. Still in the first year or two, some checking began. So he put some epoxy into the emerging cracks, which I am sure helped arrest the process. In the last 20 years, the pieces have completely dried in the arid West. Today, the slabs have some surprisingly minor cracks, but none that threaten the stability.

My questions/concerns:

1) How can I end up with a nice table-flat surface?

At the moment, the surfaces are chainsaw-rough. I am planning to use my belt sander to get to ultimate smoothness, but am worried that it may result in a "wavy" surface.

2) Suggestions on any cracks/voids - fill with... or leave'm alone? My father mentions something about using the sawdust for fill...

Thanks in advance, Stumper

[bridger]

get a router with some balls. one of the 10amp+ models should do the trick. make a base for it that positions the bit at the center of an

8' sled. set the slab up with some nice straight 2x6 rails on a sturdy base and plane off the high points until you get a flat face. flip and repeat, then sand for finish.

[Morris Dovey]

| 1) How can I end up with a nice table-flat surface? | | At the moment, the surfaces are chainsaw-rough. I am planning to | use my belt sander to get to ultimate smoothness, but am worried | that it may result in a "wavy" surface.

You could use a router to cut the surfaces flat, parallel, and smooth.

| 2) Suggestions on any cracks/voids - fill with... or leave'm alone? | My father mentions something about using the sawdust for fill...

Sand the surfaces twice. Use the dust from the first sanding to make a filler to be smoothed by the second sanding. The pieces might even be more interesting if you accentuate the cracks rather than trying to hide 'em. How you go about this will probably be governed by intended use and desired finish...

-- Morris Dovey DeSoto Solar DeSoto, Iowa USA

[Dave in Fairfax]

Stumper wrote: snip of wood acquisition

Use a large hand plane set for a fairly fine cut from the edges toward the center to avoid tearout. DON'T sand. Finish with self-leveling epoxy table finish. That'll take care of the cracks, and give you a waterproof finish.

Dave in Fairfax

[gpdewitt]

They're talking about sawdust mixed with glue, finish, epoxy, etc., which is a legitimate technique for filling cracks and holes. You could also buy or mix up some black epoxy for the cracks, makes a dramatic look. If there are any cracks possibly threatening the structure, you could rout out one of those hourglass shaped holes and fill it cross-grained with a matching plug. Routing with a sled running on rails will work great. Belt sander with coarse grit will too, if you use a straight edge to monitor your work. Once you get close, you could also take it to a cabinet shop or a mill and rent their wide belt sander, you should be able to flatten and smooth it in less than an hour, should cost less than $35. Have fun, and post a link to pics when you're done!

[CW]

[Bruce Barnett]

Try it, and then use a flat ruler, mark the high spots with pencil. Repeat.

People use a smoothing plane to make a flat surface as well.

[Don]

What I've done is get it roughly flat on both sides using a 7" disk sander with 16 grit paper, then epoxy fiberglass to the bottom face for stability. Top gets a smoothing finish with the belt sander, trying to get fairly flat, but I don't try to get it perfect. Light coat of epoxy on the top, then my girlfriend paints something on the top (one is a gorgeous deer in the woods scene). A couple coats of Envirotex epoxy (slow curing, self-leveling) seals the top, fills the cracks, and adds dramatically to the contrast and depth of the painting. You have the advantage of a fully dry piece - I usually start the process when the wood is partially dry- before it starts checking too badly, and then spend several months on the above process, putting the final coat of epoxy on after the wood seems to have finished all it's moving and checking.

Don

[Stumper]

Thanks for the advice above. I think I understand the Router Strategy

- it's essentially using the router as a milling machine with flycutter. This is probably the right way to achieve a very flat surface. However, devising a rail system that you can move the router with and yet remain level and stable seems a complicated setup. I dont have the stuff for the sled, so its beyond what I can do at this pt.

The Planing strategy is pretty simple, but has several variations.

So here's my plan: go out an buy a power planer (3.25 inch). Figure that this has a bigger swath than a hand plane, so it may make achieving a flat surface easier and will be considerably faster than by hand. Now, I have never used a power planer. Speaking theoretically: I'll use a very low setting to slowly shave off the top surface of the slabs. Ruler technique to hit high areas preferentially.

Once the surfaces are pretty flat, I'll use the belt sander and progressively finer grits to take it down to smoothness. Before it gets super smooth, I'll eval the cracks/voids and determine the fill strategy. Either leave alone, fill with sawdust/epoxy mix, or even a contrasting fill. Then sand any fill used. Take it down to ultimate smoothness by misting the slab with water to raise the grain and then hitting it with the finest grit and a finishing sander.

My wife said she likes the feel the grain of the wood, so probably will not go with the self-leveling epoxy table finish. Rather an oil or wax finish at the end.

If there are cautionary points to this strategy, pls continue to give your opinions.

Thanks again, Stumper

[CW]

The router setup would be my choice and is not at all hard to make. If you go with the plane, work from outside toward the middle. If you run off the side, you will likely tear chunks out.

[Dhakala]

Before you decide that the router sled is too complicated, take a look at this:

[bridger]

that'll work. watch for dirt in the end grain- it'll kill your blades.

not an issue with an end grain cross section slab. end grain won't raise.

you might want something more than oil-n-wax for this table. end grain is pretty open, and the slab is cut the most vulnerable way- both in terms of moisture being able to penetrate into it and in terms of the consequences of moisture penetrating. poured on epoxy is an ugly thing to do to a nice piece of wood, for sure. consider a tabletop varnish. apply the first coat or six thinned roughly 50/50 with turps to get it to penetrare down into the wood rather than build up on the surface. depending on species you may need to use a grain filler as well. once the wood is well protected you can build a bit, rub it out and wax if you wish.