I think this would take some experience and skill to make this joint fit right and tight. It tightens as it is tapped in. The wedge would have to be the exact length and width needed.

that is quite easy to make...

by the 2nd try you'll have it down to a science..

Ron, do you think chopping out the mortise would be best? I think it would be a good joint for bigger timbers, but for everyday joints not so much. One of the bigger problems is figuring out the dimensions on the wedges. They would have to be perfect. 

 

We will let Stick do that.  LOL

cut a conventional mortise and fitted tenon but a tad short...

slot the tenon..

slope the mortise 2~3° as shown..

draw out the mortise..

lay the tenon on the drawing...

experiment w/ the wedge tapers and thicknesses...

remember.. you are going for good and snug, not tight...

 

tip...

drill a hole where the slot ends near the tenon's shoulder.. make the hole about twice the dia as the slot is wide to help control unwanted splitting...

make your wedges single taper w/ the flats to the center and the tapers to the outside...

Edited October 16, 20187 yr by Stick486

40 minutes ago, Stick486 said:

tip...

drill a hole where the slot nears the tenon's shoulder about twice the dia as the slot is wide to control unwanted splitting...

I did not understand this part.  It may just be me operating in some sort of fog this morning though.

12 minutes ago, Cal said:

I did not understand this part.  It may just be me operating in some sort of fog this morning though.

If you drill a small hole at the base of the tenon it will not split through as the wedges are driven home. Probably not necessary on this specific tenon because there is a lot of meat there, but's really handy with smaller delicate tenons and relatively larger wedges.

The hole relieves the stress as the wedges drive the split tenons apart, theoretically the hole will stop it from splitting through to the exposed piece. Think of it like saw cutting lines into concrete slabs, if the slab starts stress cracking, theoretically the stress cracks should stop at the saw cut line.

If the wood wants to split beyond the shoulder of the tenon, the hole should stop it from going beyond the shoulder.

3 minutes ago, John Morris said:

If you drill a small hole at the base of the tenon it will not split through as the wedges are driven home. Probably not necessary on this specific tenon because there is a lot of meat there, but's really handy with smaller delicate tenons and relatively larger wedges.

The hole relieves the stress as the wedges drive the split tenons apart, theoretically the hole will stop it from splitting through to the exposed piece. Think of it like saw cutting lines into concrete slabs, if the slab starts stress cracking, theoretically the stress cracks should stop at the saw cut line.

If the wood wants to split beyond the shoulder of the tenon, the hole should stop it from going beyond the shoulder.

that's the ticket...

I think I got it now, thanks for the explanation John.

Just now, Cal said:

I think I got it now, thanks for the explanation John.

I edited for better clarity (I hope)...

might want to have a look/see/read...

Check!

not difficult at all but  please DO NOT bring the piece to me for repairs some 20 years later when the glue  fails.  You wouldn't want to take have to  that joint apart.  There is no  non destructive way to do it.

 

it's called a "stop drill", much used in metal working.  stops cracking and eliminates a stress riser.

35 minutes ago, Cliff said:

not difficult at all but  please DO NOT bring the piece to me for repairs some 20 years later when the glue  fails.  You wouldn't want to take have to  that joint apart.  There is no  non destructive way to do it.

 

Excellent point Cliff!!!!!!

Yeah, there's no easy way to deconstruct that joint. But then, that's the whole idea, no? I used that process to fasten the side stretchers of my Morris chairs to the back legs. The fronts were through mortises. 

"well, ma'am, sorry to hear about your broken table, but with the joinery, there is no way i can fix this and hide my work.  you should consider buying a new table, that i'll make for you.  it'll be really nice."

I don't see the point of such complexity in M/T joinery. If the mortise and tenon are sized properly for project and machined to fit snugly, then when glued and clamped, they should never come apart, yes? 

hat

 

37 minutes ago, hatuffej said:

they should never come apart, yes? 

no..

but that one won't...

14 hours ago, Stick486 said:

cut a conventional mortise and fitted tenon but a tad short...

slot the tenon..

slope the mortise 2~3° as shown..

draw out the mortise..

lay the tenon on the drawing...

experiment w/ the wedge tapers and thicknesses...

remember.. you are going for good and snug, not tight...

 

tip...

drill a hole where the slot ends near the tenon's shoulder.. make the hole about twice the dia as the slot is wide to help control unwanted splitting...

make your wedges single taper w/ the flats to the center and the tapers to the outside...

"cut a conventional mortise and fitted tenon but a tad short..."

 

Stick, are you saying don't taper the sides of the mortise? In the picture, it shows layout lines for the mortise and they look tapered.

I think the origins of this joint are very old and use horse hide glue. Very clever and very dependable. A very simple and strong joint. Research called the "Snork" joint.

1 hour ago, hawkeye10 said:

Stick, are you saying don't taper the sides of the mortise? In the picture, it shows layout lines for the mortise and they look tapered. 

I'm saying ''DO'' taper the sides...

15 hours ago, Stick486 said:

slope the mortise 2~3° as shown..