Strongest right-angle butt joint

[BenBen]

I am working on a black walnut coffee table and will be what I would equate to as framing the top along all four sides with 6/4 by 3" boards. The joints will be simple right-angled butt joints, they didn't want miters at the corners. My question is what is the strongest way to join these at each of the four corners? I can get at least two biscuits in at each corner, would that be sturdy enough? I think a half-lap is out at this point because I didn't account for the overlap that I would need and won't have enough extra wood to spare. Any mechanical options such as right angle brackets underneath (although the thought makes me cringe)? I just want to make sure it is strong enough to support carrying/moving the table.

Thanks,
Ben

 

[willarda]

If you read FW not too long ago on the strength of joints, you will find out surprisingly enough that a simple butt joint is not too bad. If I remember correctly, it has about half the strength of a M&T. which is saying quite a lot. I think for non-stressed situations (a coffee table top would qualify), just butting the wood together would be pretty useful. This depends quite a lot on how wide the two joint members are (the wider they are, the more prone they would be to efects of wood movement). Adding a spline or a biscuit would magnify the strength considerably.

 

[Mike Davis]

Loose tenons would be stronger than bisquick. Or dowels if you don't want to set up a router.

 

[rbdoby]

Biscuits will work, a floating tenon would be better. I'd use pocket screws hidden on the inside of the frame. Be sure to use the set up and screws for 1 1/2" stock.

Rick Doby

 

[PeteM]

If your making a solid frame how are you going to allow for movement of he field?
Is it a floating panel? If not and the frame is solid and the center field expands something's gonna give.

pete

 

[BenBen]

The center will be floating to account for expansion. I will connect the center pieces to the frame with dry tongue and groove joints. At least that is my plan...any rationale as to why this may not work?

 

[timf67]

Biscuits will work, a floating tenon would be better. I'd use pocket screws hidden on the inside of the frame. Be sure to use the set up and screws for 1 1/2" stock.

Rick Doby

+1 I know it isn't much better than angle brackets, but I have always been happy with pocket screws and you can get walnut plugs to hide them.

 

[Bas]

A couple of biscuits or a few dowels should do just fine. A half lap or loose tenon would be stronger, but even with "just" biscuits, you'd still have to pound the frame repeatedly with a large hammer to break the joint. I don't think that's considered "normal" usage for a coffee table (unless you have kids.... :rolf. The occasional lifting does not represent much of a strain.

 

[CrealBilly]

A couple of biscuits or a few dowels should do just fine. A half lap or loose tenon would be stronger, but even with "just" biscuits, you'd still have to pound the frame repeatedly with a large hammer to break the joint. I don't think that's considered "normal" usage for a coffee table (unless you have kids.... :rolf). The occasional lifting does not represent much of a strain.

Or grand kids :gar-La; A wise man once told me "kids can ruin an anvil" he was right you know...

 

[Joe Scharle]

How would a bridle joint look in your design? I can't think of anything stronger if well made.

 

[BenBen]

How would a bridle joint look in your design? I can't think of anything stronger if well made.

It would look nice, but I don't have the extra lumber I'd need (without downsizing somewhere) to cover the overlap needed for the bridle joint. Thanks though.

 

[Jeff]

Since you're already committed size-wise you'll be okay with pocket screws. Kreg has a pretty good video at their website that's informative.

Legs and aprons are fastened together as one unit, then the top is affixed to that. Pre-drilling and clamping is helpful to prevent jacking when driving the screws.

 

[Tarhead]

I use a Domino machine for this type of joinery.
http://www.festoolusa.com/products/domino-joining-system/domino-df-500-joining-system-574307.html

A router, spiral bit, edge guide for the mortises and some 1/2" scrap hardwood and a roundover bit for the floating tenons will accomplish the same results and not cost a few house payments. Just takes time and skill at setting up.

 

[Alan in Little Washington]

Are these "sides" aprons that are below the table or sides above the table? Will the legs attach to the table or the aprons? If the "sides" are aprons do they wrap the legs or butt the legs.

If the "sides" are just aprons that attach between the legs, the typical way to do this is with M&T. If the aprons wrap the outsides of the leg then you can attach them to the legs with glue and screws, or use pocket holes screws to join the aprons together before attaching the legs to them.

If these "sides" are above the table and are 6/4, there are a number of options- sliding dovetails, dowels, loose tenon, twin biscuits, etc. As sides, there will not be a lot of stress on them to pull them apart.