Joint strength test

[Bradley Gray]

Water could be a good loading scheme.

[Ronald Blue]

After looking at it again the joint isn't going to gain much added strength even with the domino's glued. I will presume the board is 3/4" thick and there isn't going to be much strength no matter how you butt the ends in a side load test. Plus using a scale with a jack setting on it would be a much more controlled break. Pushing against it as you slowly increase the pressure. You would have to revise your setup. If you need to join two boards end to end a half lap would be much stronger. Or get a finger joint router bit and use that method. I think what you've established thus far we already knew and that's that this type joint is never going to have much strength in a side load situation.