Thread: Cracked Tenon

You can glue the crack in the following manner;

Twist the timber so the crack opens further. Lay a thick bead of glue on one side of the crack, then use a vacuum cleaner hose on the other side of the crack to suck the glue through. Use plenty of glue so that the crack surfaces are completely covered. Then cramp up the wood hard; return the vacuum cleaner and prepare to deny all knowledge of how the hose has become gummed up internally...

I've successfully used this to repair mortises with pegged through tenons where the pegs were hammered in way too hard. Your timber appears to have cracked at right angles to the grain; so I'd be happy to finish the job and put it to work.

If you feel additional strength is needed you could insert a dowel or two right through the width of the timber. Do it well and it could even be a decorative feature!

I would have thought you could just turn it into spoons and start again.

OK I had a bit written about how to glue up cracks but I think your problem is the way you have oriented the wedge. A bit hard to tell from the pic but the wedge should pull the shoulders of the rail onto the leg. Not spread the tenon to fill the mortice.
Regards
John

John it cracked as I chiseled the mortise so I don’t think the wedge split the tenon

What is the timber? It looks like Radiata, 'cept it may be a bit green (colour) looking. My point is that glue is supposed to be stronger than timber, and if it's Radiata then glue should be way stronger. I've successfully repaired a fair few cracks with glue and clamps and usually they can hardly be seen, as long as it was a nice clean crack. As Chief Tiff says, a couple of dowels will add much extra strength (it's a shave horse - only you will know - you'll stop seeing it after as short as 4-5 years)

I'll be the heretic, I would open it up a bit and use superglue. It looks like it might be possible to put a few screws in it as well.

Here are some more visuals to explain the scenario of the joint.
Timber is beech for the swing arm. Crappiata for the footplate. Unknown hardwood peg.

will take advice ( except Shane’s ) and glue but not screw. Probably use dowels.

My my problem is that this may go outside the shed and show that I’d be better off leaving it at home and practicing my flat woodwork. That’s the trouble with delusions of grandeur I guess.


any ideas to fix mortise gaps ?

Originally Posted by Pac man

My my problem is that this may go outside the shed and show that I’d be better off leaving it at home and practicing my flat woodwork.

Nah, simply a matter of getting the narrative right. You found the timber in a dumpster outside a joinery right? Take it from there.

Originally Posted by Pac man

any ideas to fix mortise gaps ?

Epoxy & Pine dust?

I recommend adding the dowel.

I like the Chiefs idea of using a vac to suck the glue through into the crack; I'll have to try that!

I've had similar problems in the past and my work-around is to drill a hole where I'll fit the dowel, but initially using a smaller sized drill bit and only drilling down to the depth of the crack, not all the way through. Making sure I can blow air into the hole and it vents out through the crack.

I then dilute a small amount of PVA with water, about 50:50 - exact doesn't matter, so long as it's runny enough to pour down the hole and then use a nail head or similar to "piston" the glue into crack. (You can try to blow it through... but you need a good set of lungs!) Clamp and let dry.

Later, I redrill the hole all the way through at correct size to fit the dowel. As the Chief said, it's easy to make the dowel into a feature.

Originally Posted by FenceFurniture

Epoxy & Pine dust?

Bigger tenon?

I’d just glue it and not add anything else to the split.
I was wondering if the tusk tennon is just so you can assemble and glue once or does it have to come apart for transport or adjustment ? If it’s just for assembly and being glued then you could add an extra fine wedge into the footrest mortise adding pressure to the crack while your glueing up . After the first crack glue up is done and dry .
Rob

Originally Posted by auscab

I’d just glue it and not add anything else to the split.
I was wondering if the tusk tennon is just so you can assemble and glue once or does it have to come apart for transport or adjustment ? If it’s just for assembly and being glued then you could add an extra fine wedge into the footrest mortise adding pressure to the crack while your glueing up . After the first crack glue up is done and dry .
Rob

Has to come apart for the assembly to be removed for transport.

Originally Posted by Pac man

any ideas to fix mortise gaps ?

trim the mortice to square and make a new peg.

There's no reason that the peg can't taper on three sides

Yep, totally agree with Ian on the mortice matter.

The mortice is perfect. The peg doesn't fit

Straight square sides will make it easier to get the new peg to fit well though.