Page 1 of 2 12 LastLast
Results 1 to 15 of 16

Thread: Need slab advise

  1. #1
    Join Date
    Apr 2010
    Location
    Westfield, Indiana
    Posts
    95

    Need slab advise

    About five years ago I purchased some Tatajuba slabs, air dried for eight years, thirteen years by now. I had in mind a Nakashima style desk and dining table. The slabs are about 3 1/2 thick 16-24" wide, and weigh about 300 pounds each. They were so unwieldy that two people could barely lift one. So I never dived in and did anything with them, they just took up floor space. I thought of ways to lighten them like drill big holes in the underside. But what if that causes them to warp? The other day I got the idea to find someone who could resaw them into book matched slabs each about 1 1/2" thick. Sounds impossible but finally I found a fellow out in the middle of nowhere who cuts native hardwood slabs. He has a horizontal bandsaw that is powered by a 4 cylinder Kabota diesel engine. Worked like a charm. Afterwards he showed me this huge pile of KD walnut slab pieces 3" thick which were cut offs and hunks of slab not big enough to sell as full slabs. It was a pile about 4 feet high. He asked if I would give him 100 bucks for it and get it out of his way. Being a turner as well as furniture guy I envisioned the turning blanks I could make. I whipped out my wallet and with his help loaded it onto my truck. I ended up with 36 turning blanks 6-20" diameter. As a bonus I milled enough lumber out of it to complete the cut list for the trestle I plan to build for the Tatajuba table. I'm going to build the modern trestle table in FWW#235.

    Now here's where I need advise, never having gone the slab route before. As can be seen in the photos the slabs have a series of crescent shaped checks in them as well as a few minor longitudinal cracks. Since I have a can of bronze dust which in bygone days was used to bronze baby shoes (that's another long story), I was thinking of mixing some bronze dust with epoxy and filling the checks. Will this work or just create problems down the road? I know that butterfly keys are used for longitudinal cracks, but will these curvilinear transverse cracks require keys, or just epoxy. I plan to joint the inner edges of each slab and attach them in the middle with a double row of biscuits and then a series of butterflies on the surface. Is this reasonable? I will trim the ends off so that the table only measures about 76" long and 44" wide. That will lighten it up a tad as well and I think the husky trestle will support it.
    I would greatly appreciate and suggestions.
    Attached Images Attached Images

  2. #2
    I have used epoxy in circumstances almost identical to yours and it has been fine, for 15 years anyways. Use high quality epoxy, not quick set but slower set.

  3. #3
    Join Date
    Mar 2003
    Location
    San Francisco, CA
    Posts
    10,304
    Like Chris, I've used epoxy to fill big cracks in walnut. I like the idea of loading your epoxy with bronze. I *think* that the usual wood-sanding process should be able to handle the bronze content, but I'd certainly try it out on some other piece of wood (maybe those ends you're going to trim off?) before I tackled the real pieces.

    Another filler you might consider is crushed gemstones -- turquoise, malachite, etc. Turners regularly used this material to fill big cracks. The material is easily acquired from turner's supply places. The stone is selected for color (of course), and for compatibility with the usual sanding abrasives.
    Last edited by Jamie Buxton; 09-18-2016 at 10:11 PM.

  4. #4
    Join Date
    Apr 2016
    Location
    Tasmania
    Posts
    2,162
    Glenn, as the other guys said, epoxy is a good way to go. Bronze tends to be a bit wear resistant so I would get most of the sanding done before filling the voids. I am doing a small job where the filler is epoxy with added aluminium flakes. Looks great. Cheers
    Every construction obeys the laws of physics. Whether we like or understand the result is of no interest to the universe.

  5. #5
    I'd just use epoxy.

    Unsolicited aesthetic advice: I wouldn't bronze it. Just use a clear or blackened epoxy. I would also arrange the slabs as you have, with the feather in opposite directions. And There's no reason to add butterfly ties, IMHO. The feather and the checks provide so much visual interest, that keys across the joint would just be gilding the lily. That grain match is good, and the seam has a chance at becoming invisible; I wouldn't draw attention to it with keys.

  6. #6
    Join Date
    Dec 2012
    Location
    Bedford, NH
    Posts
    1,286
    I must be missing something , but why not just mix sawdust from the wood with clear epoxy to achieve the same coloration?
    Thoughts entering one's mind need not exit one's mouth!
    As I age my memory fades .... and that's a load off my mind!

    "We Live In The Land Of The Free, Only Because Of The Brave"
    “The problems we face today are there because the people who work for a living are outnumbered by those who vote for a living."
    "
    Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill

  7. #7
    Join Date
    Apr 2010
    Location
    Westfield, Indiana
    Posts
    95
    Thanks for the replies everyone. I'm glad to see that nobody seems to think that butterfly keys are needed to stabilize the slabs and Prashun has a good point that keys would make things too busy. After having had the slabs resawn to reduce weight I see that an added benefit is that I now have a 46" wide top with book matched figure. The feather figure is a full 76" long which may be close to some sort of record. I don't want to louse this up by adding distracting details. I have used sawdust in epoxy before and it's an option and would make the cracks inconspicuous. I was thinking that bronze colored filler would be decorative but complementary and not distracting. I'm not sure it would be much harder to sand that plain epoxy. I'll do a test now on a crack in a section of wood which I don't plan to use and post a photo within 24hrs.

  8. #8
    Join Date
    Apr 2010
    Location
    Westfield, Indiana
    Posts
    95
    I mixed 1/4 tsp bronze dust with 4oz epoxy and filled cracks in a waste piece. When hardened I gave it a quick belt sanding then wet sanded it with WATCO Teak oil and 400grit. Results below. I'm anxious to get opinions, go or no-go on Tatajuba, bronze epoxy and Teak oil?
    Attached Images Attached Images

  9. #9
    I think Prashun called it.

  10. #10
    Join Date
    Mar 2003
    Location
    San Francisco, CA
    Posts
    10,304
    Well, I like the bronze a lot. Black epoxy is boring.

  11. #11
    like, jamie, I like the bronze.
    Be the kind of woman that when your feet hit the ground each morning, the devil says, "oh crap she's up!"


    Tolerance is giving every other human being every right that you claim for yourself.

    "What is man without the beasts? If all the beasts are gone, men would die from great loneliness of spirit. For whatever happens to the beasts will happen to man. All things are connected. " Chief Seattle Duwamish Tribe

  12. #12
    Join Date
    Apr 2010
    Location
    Westfield, Indiana
    Posts
    95
    I'm leaning toward bronze myself although I haven't filled any cracks yet. My wife and I were able to heft the slabs onto the Big Grizz jointer and joint one edge on each. They came out better than I expected. I did some glue testing on scrap pieces of Tatajuba. I cleaned the wood with acetone to remove any resin then did a test glue up with Tightbond III. Turned out extremely strong, couldn't knock it apart with a big hammer. I put a double row of biscuits in the table slabs and glued them up. The glue line looks better than expected and I don't see any need for keys from a strength standpoint. Next I need to commit to the epoxy fill..
    Attached Images Attached Images

  13. #13
    Join Date
    Aug 2013
    Location
    Princeton, NJ
    Posts
    7,254
    Blog Entries
    7
    Fwiw, I would not use so many biscuits on a future project, if you need alignment a shallow tongue and groove would do better and offer much less risk of cracking.

    There is a lot of grain runout in the edges, so adding a shallow mortise for those biscuits very close to the top and bottom edges creates a place for that grain runout to crack.

    Many slab tables are not joined but left as a split top, that is done for a few reasons, one is that it is hard to join large figured slabs which will not move evenly at their edges. The second reason is that it makes the top unwieldy, needing two people to move it and finally it doubles the amount of wood movement that your battens will need to contend with.
    Bumbling forward into the unknown.

  14. #14
    Join Date
    Apr 2010
    Location
    Westfield, Indiana
    Posts
    95
    Thanks Brian, you make good points. I guess I got lucky, the glue is dry and it turned out very well so far. The reason I used all those biscuits is that I was afraid that the great weight and leverage of the two big slabs would pull the joint open when it's moved. You're certainly right, it is quite cumbersome to move. I think when it's done I'll put the base in place in the dining room and invite five friends over for dinner. When they get here I'll ask them "by the way would you help me carry the table top in from the workshop so we can eat?" Also good point about wood movement on the battens. I may try not even fastening the top to the base. The 150# weight should preclude any tipping or sliding.

  15. #15
    Join Date
    Aug 2013
    Location
    Princeton, NJ
    Posts
    7,254
    Blog Entries
    7
    150lbs is nowhere near heavy enough for the top not to slide, and if cups even slightly it will move with great ease.

    The top has to be located using dowels or another locating system, but being that it is so large across the width you'll have to devise a way to do that while allowing for wood movement. I've done this before using interlocking battens (the ones which engaged the top allowed for movement).

    It's actually much easier to attach the top to the base, and allow for movement in the attachment.

    The top will need to be battened to remain flat in my experience. The battens will not prevent giant movements in the table top, but will help it go through seasonal change minimizing distortion.

    You are wise to have had these re-sawn down to 1.5", that will make life easier.
    Bumbling forward into the unknown.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •