Cantilevered end grain to face grain joint

[Austin Perera]

Hi all,
I'm making a modern style valence in my kitchen to span a section over the sink between wall cabinets. I'm fastening an 8ft long 7" tall 8/4 walnut board to the wall against the ceiling. I'm then going to have a dozen 20" long by 6" high 8/4 walnut boards project out from the back board piece. So the boards or "arms" will be attached to the back board and floating out over the sink, just shy of the ceiling, making it look like a small suspended slat ceiling. I'm brainstorming the best way to attach the arms to the back board. They will only have to support their own weight. I'm thinking of doing 1/2" deep dados in the back board for the arms to glue the ends in. Then I was going to do a captured dowel joint by putting a thick dowel through the top of each arm so that screws through the back board will go into the arms and capture the dowels, since screws into end grain are a no-no. Thoughts?
Thanks guys
Attachment 512718
Valence screenshot.pngdowel screws.jpg

[Dan Barber]

With it only supporting the weight of the 20" piece of 8/4, I'd be fine just using 4- 3" # 10 GRK construction screws into the end grain at each piece. Do not drill pilot holes, let the screws do their job. Mock a piece up and see how much weight you can put on it, I think you'll be surprised. Stager the screws in an alternating pattern, not all in a line or parallel to each other, think a z shaped pattern.

[Jamie Buxton]

I'm with Dan on this one. Screws don't hold as well into end grain as they do into face grain. But they do hold. Compensate for the poor performance by using longer screws.

[andy bessette]

...They will only have to support their own weight...

Avoid screws in end grain altogether--always. Keep it simple. I would just epoxy the short pieces into standard depth dados. That will be sufficient without risking splitting them with screws in their end grain.

[Dan Barber]

Have you used modern construction screws in joints like this? I think you might be surprised. Also the dado will resist any tendency of splitting of endgrain in this joint.

[andy bessette]

Have you used modern construction screws in joints like this? I think you might be surprised. Also the dado will resist any tendency of splitting of endgrain in this joint.

First, I know better than to use screws in a joint like this; they don't offer much in terms of strength, and there are many better ways of creating a solid joint (dowels, dovetails, etc) and they are unnecessary in this case. Second, the dado can only help resist the splitting in one direction: across its width.

Personally I would use WEST epoxy (because I use it for all glue joints) and perhaps wire brads to help hold them in position while the epoxy cures. Simple, dependable, foolproof.

[Edward Weber]

A 20" long 8/4 board isn't that much weight to be overly concerned about.
Dado for appearance/cleanliness and put a few long screws in there and call it done.
You could also use something like a Miller Dowel

[Austin Perera]

Thanks guys. Would there be any issue with doing small pilot holes and coating the screws in some epoxy? I know you guys are the experts but I still feel nervous about sending #10 screws into walnut without any pilot holes :-)

[Dan Barber]

No need to drill or especially epoxy, you are really overthinking this. Your 20" long 2" x"6 hunk of Walnut only weighs ~ 5lbs. Construction screws don't work like a conventional old wood screw that acts as a wedge, forcing the fibers apart. These screws will hold. Let the screw do their job, they will be most secure that way. Drill a small pilot hole in the dado to help you get the screws in the right location and then drive them in with a impact driver. These are the type of screw I'm referring to in the below picture, available at you local bir orange store.

Screenshot 2023-12-29 082022.jpg

EDIT: If you have trouble driving them fully in or the rare chance of a split, GRK does allow for drilling a pilot hole. I don't think you'll need it, test on a pied first. GRK says the following:

"Installation troubleshooting of hardwood:
▪ GRK RSS does not require predrilling of the wood. However, if the fastener is not fully driving in very hard/dense wood such as mahogany or if there is excess torque causing the wood to split or causing the recess to strip. We suggest trying to predrill a pilot hole to facilitate installation in these cases. Pilot hole instructions below.
o If predrilling a pilot hole: For screws which will be loaded in tension, a pilot hole with a diameter of approximately 70% of the minor diameter of the screw may be drilled in the side member and in the main member to a depth of 50% of the thread length of the screw.
o For screws which will be laterally loaded, a pilot hole with a diameter of approximately 90% of the minor diameter of the screw may be drilled in the side member and a pilot hole with a diameter of approximately 70% of the minor diameter of the screw may be drilled in the main member to a depth of 70% of the thread length of the screw.

[Kevin Jenness]

Screws alone will be fine, add some glue for a little extra strength. Dados are superfluous except for positioning, and you will have to make stopped dados unless you want to show the unfilled channel at the end of the 6" wide struts in a 7" valance. Absolutely drill pilot holes in the end grain the diameter of the screw shank. GRKs are good screws but I would be confident using my shop standard #8 screws. There will be very little stress on these joints.

[Jamie Buxton]

Thanks guys. Would there be any issue with doing small pilot holes and coating the screws in some epoxy? I know you guys are the experts but I still feel nervous about sending #10 screws into walnut without any pilot holes :-)

I always use pilot holes. Particularly into end grain, where splitting may be a problem, pilot holes are a good practice.

[Mike Henderson]

I always use pilot holes. Particularly into end grain, where splitting may be a problem, pilot holes are a good practice.

I agree with Jamie. I'd do pilot holes - but that's just me.

Mike

[Lee Schierer]

I agree with Jamie. I'd do pilot holes - but that's just me.

Mike

I would also drill pilot holes the size of the root diameter of the screw being inserted.

[Dan Barber]

Stubborn crowd, pilot hole can't hurt. Here's a picture of a piece of 3/4" hard maple about 5 inches long with a #9 x 3-1/8" GRK R4 driven via impact driver with no pilot hole just now. If they don't split this, I don't think they will split the walnut at twice the thickness...

PXL_20231229_193743526.jpg

[andy bessette]

Stubborn crowd...

Hard to believe that so many "woodworkers" are recommending screws into end grain as a proper means of joinery.