Large Forestry Forum redwood display table for sawlex.

[Jeff]

Burlkraft gave the Forestry Forum a couple slabs so we could make a huge table for taking to show at sawlex.  We have been throwing around ideas on how to limit some checking on the top. not small checks, but the great big spread open movements.  We discussed screwing vertical grain supports underneath and gluing them on the ends.

I was just playing with photoshop to show this idea and see what ya'll thought. Rather then having cross peices that show, routering in channels and pockets across the top and using all thread to secure it. Put one every 2 or 3 feet. 

Do you think this idea has any merit?

[Furby]

You could use some butterflies instead.
If ya use the bolts, put em on the bottom. ;)

[Dan_Shade]

how about a vacuum bag dryer thingy?

I've seen Den Socling allude to helping a woodworker making a large slab table top for Jerry Seinfeld that way.

If it can be done, what an awesome way to do it and document it for the group!

[metalspinner]

I don't think you can stop a large crack from happening other than kiln drying it.  If you were going to keep an existing crack from getting larger, I think the all thread idea is good.  One addition may be a spring on one end of the rod between the nut and washer.  This will still allow a little movement.

I also like Furby's idea on the butterflys.  They are very attractive on the show side.

One idea I have been playing with for a large outdoor table slab is to rout a dovetail groove across the slab.  Then install a sliding dovetail bar several inches tall in the slot without any glue.  I wonder if this will help prevent warping across the top while still allowing movement.  Of, course, you will see the bar at the ends of the slab.

[Ianab]

Whats the moisture content of the wood now?

Thats going to determine how much shrinkage will occur.
I would be very wary about constraining the movement of the top in any way, thats sure to cause checks at some point. If you are worried about end splitting as it dries out more, try wrapping the end foot of the slab in plastic to slow the drying at that point.

The good news is that redwood has very low shrinkage values, so it's about the easiest wood to dry big slabs. The age of the log should help too, it must be at least semi dry by now.

Cheers

Ian

[TexasTimbers]

You would be convicted of Defacement of a Historic Slab if you allowed them to be seen from the top. I'm not sure what I think about it yet anyway. It seems to me it has been drying for only a few years didn't Steve say it was only cut down 10 years ago? MC must still be pretty high in the middle of that huge chunk of wood.

What thickness is the slab?

[Tom]

Since the log has been laying there, bucked, all these years, I would be tempted to keep it involved with mineral oil and hope that any water inside would be replaced.  The mineral oil would help protect it from erratic drying.

Mineral oil can be purchased from a feed store a lot cheaper than from a pharmacy. 

[Corley5]

Stumpy checked the wood with his meter as we were sawing.  Once we got into the log it was a pretty consistent 20%.  The outer portion that had been the top side was very wet but not very far into the log.

[Corley5]

It seems to me it has been drying for only a few years didn't Steve say it was only cut down 10 years ago?

Near as we could figure it was cut down around 1960.  One spectator said it had been in the area around 40 years having been in that location for 10 or so.

[Sprucegum]

If you're gonna be manhandling this thing from show to show I think you should put hidden all-thread just like you have drawn. One at each end about 8 or 12 inches in would not only stop the checking, it would keep the top from busting in half when you drop it  :-\   

[Jeff]

The slabs already have long end cracks. I just dont want then to get real bad. Bad means, destroying the slab.  I want to maintain as much length as possible as this is part of the awe of looking at the chunk of wood.  Cracks don't bother me, chunks falling off do.

[Furby]

Here's the kicker...........
If you put the bolt in as drawn, and you go too long with the bolt, the wood can cup and pop the bolt out.
Same sort of thing if you were to put the bolt or bolts in the wrong place along the length of the check.
Too far towards the end and you could cause the check to open up farther along due to stress.
Putting one bolt near each end will most likely end up helping to split the entire piece from end to end.

[low_48]

I would really caution about glueing anything to it. The first lesson of furniture making  is do not glue anything in a cross grain direction. Even fastening too tight in the cross grain direction is asking for trouble.

The latest method being used by the woodturning community is to soak the wet bowl blanks in alcohol,(remember, this is for the wood and not the turner). I think that at 20 percent this might not be too effective.

My favorite method to slow drying is to wrap the wood with paper to slow the moisture exchange. Maybe if you wrapped the ends with brown paper it would slow the end drying and limit checking.

With less than a month before the show I would consider using WATCO oil after any sanding or planing. If the ends see plenty of oil the checking will be minimized as well. WATCO will work okay with the 20 percent moisture.

I read some of the new posts while typing this. Maybe you something like this for storing and shipping. http://woodcraft.com/family.aspx?familyid=321 You cut the 2x4's and add the hardware. It will prevent cupping and will keep pressure on the ends.

[Sprucegum]

How thick are the slabs?

You could do butterflies on the bottom side if you don't like the bolt idea. If you do use bolts don't let Furby tighten them  ;) you just need enough tension to hold the wood where it is, you can't put those cracks back together once you got'em.

Another trick you might try is to fill the cracks wih epoxy resin - not always garranteed to hold though.

[Jeff]

The slab is 3 inches thick, 5 foot wide and 19 foot long.

[Gilman]

Jeff,
I'm sure your bolt idea will help.  You just want to make sure your bolt axis is in the neutral axis of your table (1 1/2" for a 3" board)  This will keep from loading the beam unevenly.

How about the bolts for now until it is dry and then add butterflies top and bottom once it is dry next year?  That way you can have a new table two years in a row.  ;)

If you use 1/4" bolts I have some 1/8" stainless steel rectangular washers I made a long time ago for a similar application.

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They're kind of shapped like the above but without the dashes and gaps.  ;D

[Wyatt]

Jeff,  my opinion would be do nothing or dry it now. Putting bolts in would work if it were dry. Putting them in now, when wet will cause the wood when drying to split next to the bolt (one side or other or both). When dry, a combination of bottom bolts and top dutchmen would do fine. Google George Nakashima, a pioneer in slab furniture, did it that way all his life, now his daughter runs the business. For the uniquness of the slab you have, end checks are part of the look and feel of the piece. If worried about breakage, screw some battens on bottom for transporting and handling and take them off when there. Dean

[Jeff]

Dean, that just may be the way I go.  The slab needs to be at Sawlex, so I'll be doing something with it this weekend to make it into a table. Everyone that comes to Sawlex will be able to see it.

[Gilman]

Jeff,
Do you have any pics?  Does Burlkraft have any of the slab being made?

[Dave Shepard]

Well, if this thing is going to be a table, why not build a frame underneath it and attach it with short lags on the bottom. This way you could incorporate some cross pieces to limit the expansion across the slab. And while you are at it, you could put a set of wheels in the middle so you could move it like one of Jim Rogers timber movers. I don't know the bdft weight of redwood, but this must weigh over a half-ton.


Dave

[Jeff]

I can get some photos tonight when Tammy gets home, and if it isnt raining. We'll uncover it and get a few shots.

[Jeff]

I'm guessing it weighs around 600 lbs?   Pure guess...

[low_48]

Well, if this thing is going to be a table, why not build a frame underneath it and attach it with short lags on the bottom. This way you could incorporate some cross pieces to limit the expansion across the slab. And while you are at it, you could put a set of wheels in the middle so you could move it like one of Jim Rogers timber movers. I don't know the bdft weight of redwood, but this must weigh over a half-ton.


Dave

"Limiting the expansion" is like trying to limit erosion. Mother Nature just ain't going to have it! Something will always give, bow, or crack more, if you try to limit wood movement. A sliding joint is the only way to reinforce it, not limit it.

[DWM II]

I wish I could tell you something that would help, but it sounds like it just needs to dry as naturally as possible. Good luck with it and regardless it'll be a fine piece of wood no matter the little characters it develops.

[Furby]

And the tool box says.............
Green weight would be 1111 pounds.