Thread: Closing a big bridle joint, case hardening?

Kinda hard to picture what you're referring to. Images help a lot.

I've had issues with hand cut M&T joints before too, my solution was to cut a groove in the tenon and then put a wedge down the groove once the joint was together. THat way you aren't relying just on the glue for strength, you also have the wedge providing a mechanical force to the joint and the other bonus is that it ensures the tenon fits nicely within the mortice walls.

Good Luck

.3 mm isn't much in a wooden joint. Am I getting this right? If that is the problem then just glue it up and the glue will fill the gap and it will hold forever.

Agree with Len.

Just be aware that the glue type could make a difference, there is more to the glue world than white/clear PVA.

If it were mine, and I had a concern, I would probably use a polyurethane glue. It does foam up a bit which fills any gap, just to make it easier on yourself, remove any excess before it fully hardens.

Originally Posted by Bob38S

Agree with Len.

Just be aware that the glue type could make a difference, there is more to the glue world than white/clear PVA.

If it were mine, and I had a concern, I would probably use a polyurethane glue. It does foam up a bit which fills any gap, just to make it easier on yourself, remove any excess before it fully hardens.

The foaming action of Polyurethane glues such as Gorilla Glue, and Selley's Polyurethane glue, is a side effect of the chemical reaction that occurs as the glue reacts with moisture in the timber during the curing process. The foaming action of polyurethane glue is not intended by the glue manufacturers to be an adhesive that can span gaps !

According to the manufacturer, Gorilla Polyurethane Glue can fill gaps (note that the manufacturer uses the words "fill gaps" and not "span gaps" - two very different thngs) up to 1 or 2 mm, BUT, the glue can only provide a strong bond when the two parts being glued are appropriately clamped in close contact with each other. Polyurethane glue foam has minimal strength, mainly as a result of the foam consisting mainly of bubbles of air. This is easily confirmed when you note how easy it is to cut off the polyurethane glue foam that squeezes out from joints.

To separate the facts from the fiction created by the glue manufacturer's advertising and marketing organisations, have a look at this independent discussion and review of the properties of Polyurethane Glues; the article was published by Popular Woodworking Magazine. http://www.popularwoodworking.com/ar...yurethane_glue

In the case of this bridle joint that is a bit loose, I'd simply glue up with PVA, Polyurethane, or Epoxy, and clamp firmly to hold all of the joint's faces in good contact, and leave the clamps in place for 24 hours - longer in cold weather with slow curing epoxy. Just remember to select an outdoor rated glue if the item will be exposed to the weather.

Hope that info helps.

regards,

RoyG

Thanks for that info.

I usually use Titebond III, have used polyurethane occasionally without problems and not fully investigated the advertised gap filling.