Failing glue joints - why?

[julianf]

Im trying to glue up three simple boards, size about 14.5mm x 65mm. Im wanting to glue them on the short face (the 14.5mm one).

Theyre only about 50cm long.

Yesterday, i tried cascamite structural, mixed as per directions. Took out of the clamps this morning, and the drips were still mushy.
Joint failed as i tried to flatten off on the jointer.

The wood is some unknown hardwood - looks a bit like oak, but probably isnt.

Ive planed the edges to clean them again, and now theyre in the clamps again with some random PVA. Im tightening the clamps to a bit under the limit of what is achievable with one hand - ie fully tightening them up firmly, but its not like ive put a crow bar on them.

Is it just that i cant glue two joints in a 195mm x 14.5mm sheet? Ive watched videos where it seems entirely achievable, so i dont know where im going wrong?

 

[Woody2Shoes]

Hi - two possible causes that spring to mind, maybe:

Low ambient temperature?
Shelf life exceeded?

Cheers, W2S

 

[kevinlightfoot]

Are you trying to glue end grain?

 

[RobinBHM]

old glue or low temperature.

UF glue like cascamite is very temperature dependant, which is why its commonly used in heated presses, high temperatures have a short cure time (minutes).

 

[julianf]

Glue is recently purchased, so i hope within date.

Temp may be an issue - i left it to go off in an unheated outhouse.

I watched a few you tube vids which suggested i may be clamping too hard.

Im not trying to glue end grain.


Should a glue like cascamite go glass hard when set, or should you be able to mark it with your fingernail?

I assumed it set chemically (like 2 part epoxy) but it seems more like it dries?

Thank you all for the continued support!

 

[transatlantic]

Test a piece indoors.

 

[Cordy]

It should set like glass; with a white tint

The remains of your glue from glue-up could have been left in same out-house to check

If you try again, try to leave the joint in a warmer room

 

[MikeG.]

Bring it in the house to go off in the warm overnight, and don't take the slightest bit of notice of any tosh about clamping too tight.

 

[hawkeyefxr]

I use Titebond or Gorilla Glue as i had a fail joint in the summer. I made some test pieces of 2in wide about a foot long, I just lapped the ends so there was a 2*2 joint area. With Titebond the wood itself was destroyed, the joints stayed put. Gorilla Glue was the same, i like this glue as you only apply the glue to one surface and just spray the other surface with water.
Having said that i would not glue up in the temps we have been having for the past couple of weeks, i would take it indoors where its warm.
Casamite i have yet to try but i like the sound of it.

 

[bench_monkey]

Cascamite is massively temperature dependant in my experience, over tightening is a load of old cobblers as well. As long as you’ve got the pieces all level and alternate your clamps so you don’t bow it you can crank her up. Rough the edges to glue with a sanding block, I always try to biscuit or domino for extra glue surfaces. Put plenty of glue on (but not stupid amounts) and give her what for on the old clamps. If the wood feels oily, give the glue surfaces a quick wipe with thinners before gluing (let that dry before gluing). This isn’t fool proof but in my experience these are my tips.


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