tabletop construction

I will soon be building a table top (approximately 36" x 72") out of kiln dried, native, Texas mesquite. Since mesquite rarely comes in long lengths I have decided to rip the 3'-5' boards (4/4 thick) into 1 1/2" wide boards and glue them together edge side up--with one butt joint for each 72" board. I will stagger the end butt joints so that no two are beside each other. With this in mind, I respectfully ask the members of this forum for answers to the following questions: (1) will glueing the boards together "edge side up" eliminate lateral expansion/movement? (2) will I need to use biscuits for such a glue-up or will jointed boards and glue be strong enough? (3) is there a better way to construct such a table top out of such boards?
Your suggestions have never been more anticipated or appreciated.
Dick Pewthers Austin, TX
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Well you have a good amount of gluing work ahead.
A face joint of 1.5inches will be very strong. Biscuits or dowels do not add any strength to such a joint since you have so much surface area being glued. They do help alignment. In my experience dowels help alignment more than biscuits, but take longer. Biscuits may be faster for you and should help with the vertical alignment to minimize sanding or planing once glued up.
I suggest you use a good straight edge to support the first few sections in order to get the assembly started out straight. Although you could edge joint later, I think you would hate any visual joint lines which are not straight.
I think the butt jointing will not be a problem. Manufacturers of table tops made in this fashion normally finger joint the boards. I do not know if this adds strength, but may make it easier to handle the strips in the manufacturing process.
I have a purchased table top of about 36 x 48 which is made of strips of beech or some light wood which is made from random short lengths glued together using finger joints for the strips. The strips are then face glued to each other.
I have not observed any movement issued with this table top. It is not a high quality piece, but it shows no signs of splitting/cracking. It has been finished with water based varnish. It sits in a heated room.
If your wood is dried to the average moisture content of the room in which the table will be placed you will eliminate future cracking.
I think the main movement issue to address is the fastening of the table top to the table frame. The overall assembly will expand and contract, so you need to allow for this movement in the attachment. Places like Rockler and other hardware stores sell special brackets for attached a table top which allows movement. The bracket is screwed to the top and has a lip which sits in a groove in the frame. This holds the top down, but allows for the top to move with moisture changes.
Dave Paine.

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Do you already have the mesquite? Is that a conscious choice or is it something you had easy access to? It seems like your construction choice will be a lot of work that will eliminate the opportunity to show much wood figure. If you haven't committed already, perhaps reconsidering wood choice or looking further for bigger pieces of Mesquite should be considered. I remember a local dealer got some pieces of mesquite that were 8-10' long.
Bob Davis Houston, Texas
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Wouldn't a 3' X 6' table top 1-1/2" thick be heavy as hell? Do you really need all that beef or are you trying to compensate for voids in the mesquite?
I remember Norm Abram making an armoire (I think) out of New Mexico mesquite a couple seasons ago. He compensated for the voids by filling them with black epoxy and that gave the piece a distinctive look. It was easily machined by his power tools.
Seems to me you could reduce your weight by one third by gluing your 4/4 stock edge-to-edge and working with the character of the mesquite.
I think butt joints in the top will be OK as long as they're cut with all the faces either up or down on the same miter saw. That way, if there's any error in alignment, they'll all be even so should fit perfectly together. BTW, the joining ends that form every butt joint will have to be trimmed on the miter saw.

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I built a reloading bench top using hard maple this way. Biscuits help with the alignment but not necessary for strength. The wood will still expand and contract but at least it shouldn't warp.
The butt joints won't be a problem strength wise but are hard to pull tight if you try to glue both pieces at the same time. 72" clamps are hard to deal with over top or around all your other clamps. With this in mind, it would be well worth the money (very little money really) to get an 8 foot piece of 3/4" pipe and build yourself a clamp to span the table. Get that butt joint as tight as you can, it'll be ugly if you don't.
One way to make your wood go farther would be to make the it thinner, attach it to a piece of particle board (or plywood) and then put a taller piece on the edge to give the appearance of a top that thickness. I did that with the table top that I'm typing on right now, again out of maple.
If you have a planer, make 3 sections 12 inches wide and then put them through the planer before the final glue up. Could save you ALOT of sanding. Just make sure your final 2 glues lines are perfect.
Hope this helps.
Bryan
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wrote:

Consider making perhaps 12" wide "planks," run these through a surface planer, then glue up the planks with biscuits.
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I missed the original post, but:
Wouldn't edge gluing this into something resembling a Texas butcher block rather hide the beauty of using mesquite in the first place? Seems to be somewhat of a waste of the scarce wood. Edge gluing, with staggered but joints, sort of like a wood floor, should work well. I don't think that you really want to try to do to much to fool the eye into thinking it's something that never existed in nature.
I'd deal with the movement in the attachment to the base of the table, and let it be.
Patriarch
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I have made two small tables by using 1 1/2 inch plywood strips and glue/nailing together. They are strong enough for a 300 pounder to stand on. I was after the laminated look of the plywood edges and just used wood putty for voids.
Getting the first piece square was crucial since it was an end table and the sides intersected with the top.
One thing to consider is how you will get the top flat and even all the way across. I spent hours with a plane and belt sander getting mine fairly flat. A friend did the same table and took the top to a cabinet shop to get it run through a large planer or sander to get it even. Cost him some green but it saved him time.
Good luck with the top. It would be interesting to see how the mesquite turns out.
RonT
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There is no rule against making the boards run side to side instead of end to end. I suspect a little more work doing it that way, but it would certainly work and require much less work than you are planning. Build a simple ladder frame and lay the short boards across the frame.
OR
With a more funky look, you could "stagger" the boards using more bracing underneath the table top and run the stock end to end. That requires a good bit more work but it will certainly work. I would skip the edge side up routine.
Dick Pewthers wrote:

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Dick Pewthers wrote in

Dick,     If you haven't bought the mesquite yet, I can probably fix you up. I am just down the road from you in Llano, and have KD mesquite in the sizes you need for just such a top without all the splicing in both 4/4 and 8/4 Kiln Dried to 6-8% MC. Most of the wood is 8"+ wide. The wider boards will show off the beauty of the mesquite much better than the narrow strips. I build mesquite furniture also and can give you a hand with info on the methods I use if you are interested.         I am harvesting some huge trees right now that will yield 12 - 14+" wide boards over 8 feet long, but will be about mid to late February before they are out of the kiln since they are still out on the ranch I am cutting on in log form at the moment.     I have a price list at http://www.tbird-hardwoods.com
--
Michael Burton
Thunderbird Hardwoods
  Click to see the full signature.
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