# End Joint 2" Black Walnut Slab



## generic (Jan 9, 2014)

I purchased a set of black walnut slabs, air dried and then stored them in my shop to dry/acclimate for another year. As they dried one slab decided to warp at a large knot. I am gluing the slabs together to make a table out of them. Figuring the bend is mainly due to the knot (and less than perfect milling) and assuming there wasn't a good way to remove the bend, I cut the slab at the bend and planned on using a flush trim bit in my router to square the surface and glue the the ends back together.

After the fact I have been getting concerned about the strength of the joint as it will be about 18" from the end of the table. I have had a couple thought on how to reinforce it:

1. Use bowtie biscuits on the top surface.

2. Cut bolts in from the underside and epoxy them in.

3. Since the finished slab will be 1.5-1.75 inches thick, mill out on the bottom side along the joint, say 1" deep and 3 inches to either side and glue in a 6" wide board that would span the joint.

I was wondering what others have done and your thoughts on the above ideas. I am not concerned about the underside as it will not be seen.

Thanks in advance,

Eric


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## Unknowncraftsman (Jun 23, 2013)

Too me it your post reads like your thinking of making a structural joint on end grain across the width of the table.
If I'm reading correctly I don't believe you would be able to hide the joint on the top.
If there wasn't a similar joint on the opposite end it will look off. 
Good Luck


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## generic (Jan 9, 2014)

I am not overly concerned about seeing the joint on top. If I can't line the grain up and make it look right, I can carve out a "stream" flowing out of the void being infilled with epoxy. My main concern is making sure it holds together if someone leans on or picks up the table.


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## Unknowncraftsman (Jun 23, 2013)

Cool sounds like a adventure. 
Nice looking boards quartersawn with long sweeping lines. I like it.
Good Luck with your build.


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## Jake229 (Jan 14, 2020)

Hi Eric,
While I personally have never tried it, I have seen where people will route out for a significant piece of steel on the bottom side. Actually, they used it for attaching the legs to the slab. Please post your decision and pictures if you wouldn't mind. I for one would enjoy seeing the finished project!

Have fun with your project!
Jake


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## RyanGi (Jan 13, 2021)

I think I'd do some nice big bowties. Big, since the slabs are pretty big and they'll look nice and proportional. I'd probably also route in a couple dados on the underside and tie them together with straps like you mentioned…

Pretty slabs!


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## ibewjon (Oct 2, 2010)

How about a large half lap joint? The grain may be a better match and you will avoid the end grain joint.


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## Nick424 (Aug 24, 2016)

I would try your plan #3. Just be sure that the grain is running the same direction as the slab when you glue the piece or pieces in. I think 3/4 inch would be plenty thick for the patch.


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## bigJohninvegas (May 25, 2014)

> I am not overly concerned about seeing the joint on top. If I can t line the grain up and make it look right, I can carve out a "stream" flowing out of the void being infilled with epoxy. My main concern is making sure it holds together if someone leans on or picks up the table.
> 
> 
> 
> ...


So I am a little confused as to where the 18" cut line will be? This photo is a beautiful pair of book matched slabs.

So are you going to glue them up as pictured? In that case, perfect. As you mentioned jointing them, or flush trim the two edges. 
Then try to find someone with a Domino XL for that large of a slab. Large dowels if no domino is available. 
Adding some bowties would look nice too. But the real strength would come form the Domino, or dowel. 
And are you talking about filling the large void with epoxy? That too would look good. Add some stability. 
Good luck.


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## therealSteveN (Oct 29, 2016)

Your post reads END joint, do you mean for it to be EDGE joint? The pic would make it seem you have a plenty thick enough bookmatch. Edge would just need to be trued up, so you have good approximation, that alone will remove some of the fault.

I can see some form of epoxy, color dependent on taste, to fill the void.


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## generic (Jan 9, 2014)

Sorry for the confusion. This picture shows where I had to cut the one slab and the joint in question. To answer some of the above comments, yes, I will be gluing the two slabs together and infilling with epoxy. I am still in the slab flattening process. One side is flattened and I am thinking now is the time rejoin the piece I cut off.i may even join the two planks together before leveling the bottom side.


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## JackDuren (Oct 10, 2015)

You need to clean up the edges to make a good joint.


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## generic (Jan 9, 2014)

I understand that the face edges all need to be be trued up before gluing them together. I haven't gotten to that yet. I feel I need to complete the butt joint first, then true the faces up.

Joining the slabs together seems like the easiest part in my mind. It's the butt joint, flattening and epoxy infill that have my mind working overtime on. I have never done any of those before now. LOL a smart person would have likely started out with a smaller project with cheaper wood, but I have never claimed to be smart. ;-)


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## Jake229 (Jan 14, 2020)

> I have never done any of those before now.
> 
> - generic


 Good morning sir,
Those are the best projects! Pushing yourself towards expanding your knowledge set. You need to embrace the challenge. I still think that 3 steel plates routed out on the bottom will work best. Or as someone else said, plywood, although I believe the steel would be best!

Most importantly, have fun!
Jake


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## 1thumb (Jun 30, 2012)

Dog bones or similar?


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## generic (Jan 9, 2014)

Jake,

I had not thought about routing steel, but I am definitely considering it now.


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## bndawgs (Oct 21, 2016)

What about maybe a 1/2" thick spline 1" wide to join the two pieces? And then maybe do 2 bowties to help reinforce the joint as well.


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## generic (Jan 9, 2014)

I thought about a spline, but from a google search on the benefits, it doesn't look like biscuits or splines improve the strength like I thought they would.


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## bigJohninvegas (May 25, 2014)

> I thought about a spline, but from a google search on the benefits, it doesn t look like biscuits or splines improve the strength like I thought they would.
> 
> - generic


Correct, the grain direction of a spline, or biscuit in this sort of application has no strength. That's where a domino, or dowel come in. Or a Bowtie as well. All have the proper grain direction to give it the need strength. Only hidden vs exposed, and there will be no way to hide the butt joint, so even if you were to use domino or a dowel, some bowtie work to embellish the joint may make it look better.


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## skogie1 (Sep 1, 2014)

I would use some steel channel. I've done this for a couple of projects. Drill out some holes in the channel to allow bolts to pass through, probably 2 for each piece you're joining together. Route a dado to accept the steel channel. Install threaded inserts into the slabs to hold the bolts. Take your time with the inserts as you want them lined up accurately with the holes in the channel and you want them straight. Attach.

If you think wood movement might be an issue then use slotted holes on one side. I don't think it will be an issue if I understand the grain orientation right. I think the steel channel is running the same direction as the grain so it won't be a problem.


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## MPython (Nov 30, 2018)

I think a spline with the grain running the same direction as the grain in the slabs would be plenty strong. There would be no risk of the spline failing along a grain line. I would make it at least 2" long so you'd have 1" of glue surface in each section of the slab. I've used "short grain" splines like this in similar applications, albeit on a smaller scale, and found them to be very strong.


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## generic (Jan 9, 2014)

My concern with using channel is that the channel would be installed in it's weakest orientation. Unfortunately my engineering mind tells me channels are strong when placed on edge, with the webs being seperated the furthest and thus generating the greatest resistance to bending moment. with the wide park flush with the bottom surface, it has the least resistance to bending.

I am still working on flattening. My time tends to be limited. I am leaning towards going with option 3 and then on top, route out a free formed channel and infill it with epoxy. My thought being the epoxy will act as a structural bond/support as well as hide any discrepancy in wood grain at the joint.


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## ibewjon (Oct 2, 2010)

Just wondering, if the channel installed flat is weak, what is the table for?


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