Round the tenon or square the mortise?

[Roger Reynolds]

Round the tenon or square the mortise?

I am building a bed with 3/4" wide x 1-1/2" deep x 5" long blind M&T joints. The mortise operation was done with a forstner bit and the tenons will be done on the table saw. Do you prefer to round the tenon or square the mortise on one this large? - or doesn't it matter?

-Roger

[David Mueller]

It's easier in my opinion to round the tenon to match.

[Tom Hintz]

I also would round the tenon because it is way faster and has no significant impact on strength with a decenet fit.

[Mike Cutler]

I'm a square the mortise guy. For me, personally, it is easier to mark and align everyting off of straight lines. I have rounded the tenon also, but I prefer to have the mortise square. I don't think it matters either way though

In the example that you outlined. I would probably round the tenons.

[Cliff Rohrabacher]

I have always felt that somehow it matters that the sides of a tenon fit snugly into the mortise. However, I suspect that this notion is entirely imaginary and the effort I put into such a fit probably serves no purpose other than to satisfy my sence of order.

The grain interface on the edges of the tenon/mortice joint is endgrain-to-sidegrain( as I use a router to mortise). There is not one thing the glue will do there other than find space for sqeeze-out..

The surface area is at best minimal. The probability that a snug edge fit will support the frame and prvent racking is - well- improbable at best. This especially since the tenon sholders will butt hard up against the other piece providing plenty of racking resistance & combined with the moment arm described by the tenon and the shoulders.

So then why do I insist on making all four surfaces fit snugly? I guess it's my sense of how the universe should be ordered or some wacky Zen thing or maybe I just like the way it feels when I shove it all together. I do know that when all the surfaces fit snucly the frame parts are more self supporting in a dry fit assembly.

I ought to do a project with round mortises and square tenons leaving a gap. I should do this just to see if I suffer nightmares or the earth opens up and swallows me. Maybe my hair will fall out.

[Andy Hoyt]

I've done both - on furniture and in timberframing. Both work fine.

But to me, a square mortise speaks to the care and attention to detail summoned to the fore by the maker.

Sadly however, once it's built only maker knows.