Redfish Posted October 9, 2015 Report Share Posted October 9, 2015 In one of Mark's video's he demonstrates how to cut double mortise and tenon joints. He cut the mortise with a plunge router. I noticed he did not square the rounded ends of the mortise. Is it necessary to square the mortise holes if you will be using a non-rounded tenon? Thanks! Quote Link to comment Share on other sites More sharing options...
Tpt life Posted October 9, 2015 Report Share Posted October 9, 2015 It can be much faster to round over the edges of a tenon than to square the mortise. It is a perfectly acceptable alternative operation. Quote Link to comment Share on other sites More sharing options...
Brendon_t Posted October 9, 2015 Report Share Posted October 9, 2015 Nope. Just a waste of time. Quote Link to comment Share on other sites More sharing options...
Redfish Posted October 9, 2015 Author Report Share Posted October 9, 2015 So you'd just have to make sure that your tenon is the same length as the mortise from center to center, not the farthest quadrant of each end? Quote Link to comment Share on other sites More sharing options...
Tpt life Posted October 9, 2015 Report Share Posted October 9, 2015 I'd want as snug a fit as possible. I think this means yes to your question. The radius of your tenon edge and mortise end should match closely leaving you with an end to end match. Just to throw this out there, this is all the Domino is essentially. The tenon is loose rather than fixed, but the joinery is used a lot. Quote Link to comment Share on other sites More sharing options...
Brendon_t Posted October 9, 2015 Report Share Posted October 9, 2015 I take a different view that if I remember right, I heard from Shannon on WTS. The edge grain part of the tennon are not where the strength comes from. I pare it down not caring if there are gaps on each side. I've actually found it helpful if I need to adjust the height of a stretcher. Quote Link to comment Share on other sites More sharing options...
Barron Posted October 9, 2015 Report Share Posted October 9, 2015 The Domino has three settings for width of the mortise to allow adjustments when fitting the joint. I frequently use the tight setting on one side and the slightly larger setting on the other side and never have had a problem. Marc in some of his videos, like the Roubo build shows how to quickly round off a tenon to fit a mortise cut by a router, if you want a tight fit. Quote Link to comment Share on other sites More sharing options...
TerryMcK Posted October 9, 2015 Report Share Posted October 9, 2015 With square mortices if the tenons fit on all edges snugly then you do get more glueing area making an even stronger joint. However most people just get the fit right on the tenon faces. This then gives a little leeway to adjust the tenon sideways in the mortice by sliding it. It only takes seconds to square one off with a mortise chisel or even a regular bench chisel.You don't have to square mortices off but if you don't you will have to chamfer or roundover the edges of the tenon. Either way you will still have to do some work. Choose whichever method is easy for you. Quote Link to comment Share on other sites More sharing options...
thewoodwhisperer Posted October 9, 2015 Report Share Posted October 9, 2015 (edited) I usually wind up rounding over my tenons. While to do agree with my buddy Shannon that the real glue strength of a mortise and tenon comes from the long grain cheeks meeting the long grain mortise faces, I think it's always best to get that tenon pretty snug in the mortise. So I wouldn't make a habit of dropping a short square tenon into a rounded mortise. For most things it would be fine, but it would bug me knowing I've got a 1/4" gap above and below my tenon. I usually round my tenons manually for a pretty snug fit, and then give it just a wee bit of breathing room vertically for final positioning. Edited October 9, 2015 by thewoodwhisperer Quote Link to comment Share on other sites More sharing options...
estesbubba Posted October 9, 2015 Report Share Posted October 9, 2015 If you want perfect round mortises and tenons straight from the router:https://www.leighjigs.com/intro_mortise.php Quote Link to comment Share on other sites More sharing options...
Mick S Posted October 9, 2015 Report Share Posted October 9, 2015 I usually wind up rounding over my tenons. While to do agree with my buddy Shannon that the real glue strength of a mortise and tenon comes from the long grain cheeks meeting the long grain mortise faces, I think it's always best to get that tenon pretty snug in the mortise. So I wouldn't make a habit of dropping a short square tenon into a rounded mortise. For most things it would be fine, but it would bug me knowing I've got a 1/4" gap above and below my tenon. I usually round my tenons manually for a pretty snug fit, and then give it just a wee bit of breathing room vertically for final positioning.I agree. Even when I use a Domino, I rarely use anything other than the narrowest setting. In places that I need a little wiggle room, I plunge the Domino to both right and left of my mark, leaving maybe a mm extra. The wider slots are too wide, IMO. Quote Link to comment Share on other sites More sharing options...
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