When I had a glue line open (on air dried white oak coincidentally) it was due to over tightening the clamp on the end of a table top. I likely starved the glue line and the stress associated with differential drying of wood between exposed end grain and towards the core caused the failure. I have returned to the old school technique of springing my glue joint on solid glue-ups of any significant size. Extra down pressure on the wood midway through edge truing easing off at ends. Keep your jointer super sharp. I resist the temptation to just glue it and squeeze it if there is resistance to the joint to coming together in a dry fit.
That said, an on site hand-planed wedge and Titebond II after swabbing the joint liberally with rubbing alcohol or acetone to remove oil would do the trick.

I'm actually surprised by the sheer size of your solid-slab glue-up that you haven't had more failures on the rest of them. I wouldn't have the balls to guarantee anything remotely like this. Just sunlight shining on half of it through a window is going to make it move and move a lot. If I were you I'd start thinking about leaving town (just kidding) .

Seriously, fix it anyway you can but don't think for a second that your "Dutchman" patch is going to please anyone. Geeze man, even concrete requires expansion joints and engineered floor tiles and plank need room to move.

I'm sorry but a big glue-up like this (especially on oak) is only practical and proper when manufactured as "butcher-block". I would rethink and re-engineer your product if I were you.

jim,

thanks for the kind words. we've had plenty of success with large glue ups as a lot has to do with installation. again, this is our only failure out of a few hundred and the only one that "could" be our fault. i haven't checked the installation and the homeowner already admitted not oiling the top for 6-8 months.

what do you mean by "butcher block"? i'm familiar with the term but it is often misused or used in place of wood countertop. this is an edge grain top (as stated above) so the majority of the expansion/contraction will take place in thickness, since the pieces have been turned on edge. we've done plank constructed tops at much larger widths (93" is our widest to date) without issue.

i'd prefer to keep this less about what a dummy i am and focus to technical merits of my proposed fix. i'm married so i'm well aware of my shortcomings!

No disrespect intended, I don't know your methods but you obviously do. I would be afraid to do thisyself with no traditional joinery or anything other than a bit of glue to keep things together. Are there any transverse splines or perhaps interior threaded rod? I see no splined end-capping either, just exposed end- grain with the customers' job to keep it oiled and sealed?

It's the size of these slabs which scares me. Any open joints along the edge spoils the whole enchilada. Can you honestly say that you're not a little apprehensive about all the rest?

When we make these, they are often 2" thick or better. We will rip 8/4 rough to 2-1/4" then face and edge on a joiner, then plane to a consistent 1-3/4" x 2". We then match up for grain or randomness, and glue in one or more sessions, using bar clamps. If we start with flat sawn lumber, then the 'edge grain' that makes the surface is more like quartered or rift. This is the most common type we are asked to make.

We also do end grain tops, where all the upper surface is the end of what is essentially short blocks of wood. 1-3/4" x 2-1/4 x 3" long blocks. We will glue long strips, then send them all thru the planer - on the 'side grain' sides - to level all the joints, then glue for the other dimension.

The end grain is like the true original block that the butchers used for chopping up animal parts. Maple is also traditional for that use, and it was made with end grain since it is easier on the knife edges. A few cracks did not present a problem. If iron rods were used, they could also go thru the long leg tenons to help keep them in place during rough daily use.

Iron rods or similar have been suggested in previous Woodweb and other discussions on wood tops. To 'keep them from splitting' or to 'prevent warp' or other wishful thinking. If you think thru seasonal movement, you will see that rods will do more harm than good, unless they are allowed to completely float.

The tops will still move a considerable amount with changes in RH. A quick look at the Shrinkulator will help indicate what that movement may be on a seasonal basis.

What caused Mr Google's open crack? Can't say. I'd lean towards lack of glue on one bit of one edge. Maybe starvation with 'too much clamp pressure' (please define?). Maybe too high a moisture content. Likely since we are seeing the opening at the end grain, where wood loses /gains moisture more rapidly. Or something else. Or - most likely - two or more of the above.

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To David R Sochar: Okay I've been caught using terms I don't fully understand. I have never really understood the concept of "glue starvation". In theory I suppose it means that excessive glue pressure squeezes all or too much glue from the surface leading to a failed bond. In practice we all try for an imperceptible glue line - zero thickness? My experience with solid glue-ups and veneer too much pressure leads to local failures. Defining too much clamp pressure? I don't know I just yell not that tight! It depends on surface area, edge prep, tolerance...
To the original poster: Seeing as you have had a 100+ successful tops I know you don't need any advice on assembly but I am curious about your process and machinery.

google,

To get back to your original question, in post # 5 Mike hit the nail on the head.

Due to it's size and probably the distance from your shop, taking the top back to the shop and re-ripping the failed joints and re-glueing isn't an option.

Going beneath the top and with dowels as he suggested re-stabilizing the joints will let you make the cosmetic repair from from top surface.

The difficult part will be convincing your customer this is a legitimate way of dealing with the issue.

Good luck,

Mark

Is ripping on site with a track saw an option for you?
I'd love to see a photo of the complete top.

tom - our process is similar to dave's.

dave - glue starvation might the be answer. i have had to remind my guys about not tightening the clamps and then untightening them to make adjustments during glue up. they know this is bad stuff but occasionally forget. the other part is that we essentially start at one end and work our way down. if we don't move fast enough the glue can slide onto the floor, leaving little to hold the pieces together. neither is a day-to-day worry but either, combined with slightly damp wood, could be the culprit for this top.

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We did a huge tavern bar top several years ago. Now you've got me wondering about what it has done. Think I'll have to drive out there and see.

I wanted to comment about how fantastic your countertops look. i can see why you've made so many of them...I'll take two. The glue-ups truly are ambitious but that's what make these so special. Wood is good no matter how you slice it and you're cutting no corners that I can see. I love your work and apologize for critical comments. You obviously know your stuff.

I think the method you describe early in this thread about running a circular saw over the particular split on joint then filing it with splinter and using an epoxy adhesive may be your best quick fix option because to do it properly by re-ripping it along the joint and re-gluing it you would actually lose 1/4" because as you can see there is another crack developing along another joint which moisture Is definitely going to widen unless sealed properly. Your finisher may need to aesthetically 'touch up' the surface of the repair area so that there are no small crosscut kerf lines indicating a saw blade was there and everything just blends in one direction.

The problem with this type of construction is that the length and weight of this entire build. Youre treating this countertop like a massive butcher block and using the same joining and finishing techniques that would be used on a small 12"x12" board. And even those boards can split and warp because they're never sealed completely. You can't as they are food grade functional.
This thing is massively bigger in size and used as a countertop which is prone to unequal wieght stresses imposed upon it, heat, water, etc. and all this without dowel or some type of tenon joinery which kudos to you is all pretty incredible. I think however that you need to ditch this mineral oil finshing stuff and finish these pieces properly. They are too big and heavy to treat like they're simple cutting boards. If you want to go less toxic, use a water based sealer but seal them like you would any heavy duty piece of wood furniture. They are beautiful tops and I doubt that customer is going to start carving food or cutting vegetables directly on them. Are they really going to want to look at knife marks permanently cross stamped every time they look at their countertop? That's what cutting boards and butcher blocks are for. Leaving anything to the responsibility of the customer that affects the actual structure of your product (not just minor aesthetics like dry looking leather) is not good business in my opinion.

Just my two cents

First of all, its a beautiful top!

I have huge sympathy for you, and have been there myself. If you work with wood long enough, you'll bump into failure at some point. Sounds like your record is pretty dang good.

Lots of good suggestions. I would underscore those that have you ripping along the cracks, and regluing - if you are lucky, those wont carry through the length of that monster. Sharp blade in a tracksaw would obviate transportation, change in moisture, etc, problems.

A couple of questions I haven't seen. Forgive me if I am duplicating:

* Is the circular end sitting on a solid panel, or is it open underneath like an apron? You could have moisture transfer issues.

* Is it fastened down in such a way as to restrict movement? Some guys would be tempted to put screws at 3 and 9 oclock, which would pretty much guarantee cracking.

* Is the panel balanced? I realize oil is not quite the same as lacquer or varnish with regards to transfer, but it is still a consideration, and I would want top and bottom coated similarly.

At any rate, it is definitely salvageable, in my opinion. One in a hundred is rate I certainly wouldn't be ashamed of. Best of luck.

karl,

i don't know anything about the conditions of the install as we didn't install it. obviously, when i make the repair, i'll address anything done incorrectly then.

i've always wondered about balancing the panel with mineral oil. we certainly apply oil to both sides before it leaves the shop but most applications would make it very difficult to reapply oil to the bottom side. i guess it migrates through the wood with the help of gravity? we've done plenty of mineral oil tops without other problems and i seriously doubt anyone is oil the bottom side.

thanks.