Replies

1. 
   JohnWW | Dec 04, 2003 02:00am | #1

   Ed,

   End grain to end grain shouldn't create any stress problems since the expansion and contraction of the two pieces should be about equal. 

   Generally gluing end grain to end grain is a weak joint no matter how you do it.  I'd suggest simply butting the two pieces together and using the specialty bolts that are used to join sections of kitchen counter top, they're installed from the underside of the top and are invisible from above.  The bolts will pull the joint tight and give the joint as much strength as possible.  You might add a couple of biscuits or dowels to help with the alignment but they won't add any useful structural strength to the joint. 

   No matter how you make the joint, put some sort of stretcher assembly underneath to take the load.

   John W.

   
   

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   Edited 12/3/2003 6:06:31 PM ET by JohnW

1. 
   Sphere | Dec 04, 2003 03:15am | #2

   John, I am not so sure about that. Those bolts are designed for subtrates lacking any directional grain...they probly would just pull a chunk out the end or ay best stress a crack...a floating tenon(s) is how i would go..but thats me.  Route 2 would be a long scarf so long to long is max...

   Edited 12/3/2003 7:17:22 PM ET by SPHERE

1. 
   numbfinger | Dec 04, 2003 03:49am | #3

   How about a loose tenon drawn tight with offset pins?

2. 
   JohnWW | Dec 04, 2003 08:07pm | #5

   Sphere,

   Here's what I was thinking when I made the suggestion to use counter top connectors for the joint:

   This is for a table top, size wasn't given but I was picturing a coffee table size as a minimum, maybe three feet long with the joint in the middle.  Any form of end to end joint, whether fingers or biscuits or tenons is inherently weak in this type of situation.  Eventually the table would, at some point in it's life, be loaded to the point that the joint would fail.  My guess is that, at best, any end to end joint can only achieve a quarter of the strength of the same size top made from a single continuous board.  This is just basic physics, no amount of fancy joinery or miracle adhesive will make up for the loss of continuous fibers from one end of the top to the other. 

   Given the basic weakness of the joint, I recommended a frame of some sort underneath the top to deal with the strength issue.  So now the top joint is mainly cosmetic, it just needs to hold the two ends together seamlessly and ideally not be visible from the edges.  The simplest way to do this is to use counter top connectors which allow you to fine tune the joint during assembly and pull it up tighter if the connection later loosens from shrinkage.  I always go for the simplest method that will achieve the desired results reliably, in this case connectors filled the bill. 

   The connectors reach at least a couple of inches into the end of each board, so there would be more than enough wood surrounding the connector to handle the tension, provided the top is properly supported from underneath.  If connectors work in weaker MDF counter top material, hardwood should easily be able to handle the stress.

   John W.  

   Edited 12/4/2003 12:20:48 PM ET by JohnW

1. 
   Sphere | Dec 04, 2003 11:11pm | #6

   Yeah whatever floats the boat...most counter tops are fabbed from HDF not mdf..btw.

1. 
   EPB | Dec 05, 2003 04:23pm | #7

   Hey , Thanks for all the opinions, keep them coming. I appreciate what everyone has to say. It is a cofee table size.thanks again Ed

2. 
   SCFrankland | Dec 04, 2003 06:07pm | #4

   Ed you can pick up a finger joint router bit and finger joint the ends together. Yo will get lots of strength from the glue surface.

   Scott C. Frankland

   Scott's WOODWORKING Website

   "This all could have been prevented if their parents had just used birth control"

3. 
   Routerman | Dec 05, 2003 04:52pm | #8

   Due to a lot of crummy thin stock, most of the surfaces I glue up (5' or longer) are brick-laid. I cut the stock up in 2 unequal lengths/length, lay the stuff out, arrow & number it. Now when its glued up each row of stock over laps the joint in the next, usually x 10" or more. The whole slab is pretty strong when laid up this way. The out side stix are still vulnerable to twist tho, so I rout a lock across those joints to keep them from twisting, a mending plate of sorts.

   Routers

4. 
   jazzdogg | Dec 06, 2003 05:41am | #9

   Decorative butterfly keys and a spline (perhaps a sliding dovetail spline).

   Whether you think you can, or you think you can't, you're right.