How many dominos in a joint

[Brian Runau]

Gluing a butt joint together for an outdoor table top. 1-1/2 x 5" material. No major load on it, more for strength and alignment. Two large 50mm enough for the joint or do I need to use 4? thanks. Brian

[Randy Heinemann]

8 mm or 10 mm Dominos? Small table or larger? I assume you will use waterproof glue (something like Titebond III)? Do you own the Domino 500 or the 700XL?

Strength is due to a combination of depth of the Domino into the wood and the actual size. I would go as deep as possible so, if you have the 700XL, longer might be better, or 2 12X??, whatever length will fit.

Also, how the table top is constructed makes a difference. If the table is smallish and the use is more for setting drinks on rather than heavy duty use, 2 should be enough. It's really hard to say for sure without a picture of a similar table or a drawing. I have always felt that Dominos are as strong as standard mortise and tenon joints (since they really are mortise and tenon joints, just loose tenons), so think about how the mortise and tenon joint would be constructed.

Some of my concerns about strength are solved when I almost always overdesign things. If it makes you more comfortable and there is the space where the joints are, put more. It won't hurt and will give you a chance to use your Domino more.

[Michael Burnside]

I would use 4. Two top half, two bottom half.