Do I need to brace gate and if so how?

[flanajb]

I have built the following gate. 910mm wide * 960mm high and I want to know whether I should fit a diagonal brace. The tenons are very substantial and as you can see they have also been pegged through with 1/2" section and glued up with cascamite. I am just not sure how best to fit the diagonal brace given that end grain does not glue well?

 

[adzeman]

I would say yes. To act as a gallows it should be between 30deg and no greater than 45 deg. It does not have to go from corner to corner it can go from bottom corner up to the middle rail at 45 deg.and is in tension
A hanging brace is say between 45deg and 60 deg and is in compression. imagine your arm held out at 60 deg pulling up the bottom rail this is the action you are looking for. It needs a firm fixing into the bottom rail and another into the stile as high up as possible.

 

[flanajb]

I would say yes. To act as a gallows it should be between 30deg and no greater than 45 deg. It does not have to go from corner to corner it can go from bottom corner up to the middle rail at 45 deg.and is in tension
A hanging brace is say between 45deg and 60 deg and is in compression. imagine your arm held out at 60 deg pulling up the bottom rail this is the action you are looking for. It needs a firm fixing into the bottom rail and another into the stile as high up as possible.

Ok, but are you able to explain what is the correct way to fix the brace to the bottom rail and stile?

 

[Myfordman]

The brace should be in compression

 

[Jack (W)]

Maybe the following article will be of some help:

"Bracing situation - Design for compression"

http://thecarpentryway.blogspot.co.uk/2 ... n-for.html

Jack

 

[flanajb]

Maybe the following article will be of some help:

"Bracing situation - Design for compression"

http://thecarpentryway.blogspot.co.uk/2 ... n-for.html

Jack

Perfect! Thanks Jack

 

[adzeman]

I must admit to a bit of mischief when I stated in compression. When at college in a structures, the lecturer gave us a similar problem to solve. There were a few sign posts. The trap was the detail of the construction of the frame or gate. If the joints are all connected then what we are calling a brace is a strut and will be in tension, in other words the top rail and the stile are trying to spread therefore stretching the timber. Placing the brace over 45 deg still held but not as good as under 45 deg. Notching the brace into the top and bottom rails under 45 deg gave the best results but over 45 deg next to useless they buckled and popped out or the bottom rail sheared. Under 45 deg it basically crushed and we reclassified it as a prop or slanting post. The 45 deg related to the centre of gravity being within the area of the base. (Leaning Tower of Pisa) I think it is safe to say this member is in compression.

The best results were on the wider than height gates (Farm Yard) with a flat mild steel bar screwed to the surface it was the hinges that failed first but with band and crook hinges were virtually indestructible.

Since these experiments (and we all enjoyed making the models and destroying them). There were only 4 in my set that had been woodworkers. The results have stuck in my mind and have attempted to follow the principles in my gate constructions.