Constructing an island benchtop

[Peter Watkins]

G'day,

I am a new member to the forum, although I have had the pocket jointer for a number of years, I just didn't get around to joining you.

Anyhow - my wife and I are in the process of downsizing [in fact we are currently building our 3rd "Last House"] - as part of it I have been dobbed in to make the island bench out of timber - all edge jointed and glued out of 1 1/4" Tasmanian Oak - it is 10' long and 3'4" wide with an overhang of approx 1' - which is currently unsupported

My query is - should I have concerns about the unsupported span [1 and 1/2 boards wide]? A mate - who was a cabinet maker - expressed worries about it sagging. I intend to use 2" screws and a Sika Tech Grip epoxy glue

What does anyone think?

Peter

[Roy Coulman]

Hi Peter.  I haven’t seen any replies to your question, so maybe you’ve already finished the project.  If not, here are my thoughts.

1-1/2 unsupported boards would concern me even though they are edge jointed and glued.  I’m guessing the screws are in pocket holes, and that will help.  However, rambunctious kids and careless adults can place a lot of weight on the unsupported boards.  The joint of the first board will be affected most, followed by some slightly different forces on the second joint.

For some structural insurance, I suggest adding some biscuit joiners in the first and second joints.  Biscuits, in your application, provide 2 things.  First, they provide more surface area for glue.  Second, when the glue sets, they provide strength that will resist separation when weight is applied along the unsupported area. Yes, pocket screws do this too, but the kind of leverage the joint will experience will strip a screw out of the boards long before a biscuit will let go.  As a bonus, biscuits help keep the board surfaces in alignment during the gluing and clamping process, so less sanding is required.

So my suggestion is to do all you are doing, and add some biscuits to the first and second joints.  Please post a photo of the finished product!  

[Peter Watkins]

Roy, Thanks for the advice - you are echo-ing my concerns. I'm debating a metal angle as I have already glued and screwed the bench

I will post it when I finish

Pete

Roy Coulman said:

Hi Peter.  I haven’t seen any replies to your question, so maybe you’ve already finished the project.  If not, here are my thoughts.

1-1/2 unsupported boards would concern me even though they are edge jointed and glued.  I’m guessing the screws are in pocket holes, and that will help.  However, rambunctious kids and careless adults can place a lot of weight on the unsupported boards.  The joint of the first board will be affected most, followed by some slightly different forces on the second joint.

For some structural insurance, I suggest adding some biscuit joiners in the first and second joints.  Biscuits, in your application, provide 2 things.  First, they provide more surface area for glue.  Second, when the glue sets, they provide strength that will resist separation when weight is applied along the unsupported area. Yes, pocket screws do this too, but the kind of leverage the joint will experience will strip a screw out of the boards long before a biscuit will let go.  As a bonus, biscuits help keep the board surfaces in alignment during the gluing and clamping process, so less sanding is required.

So my suggestion is to do all you are doing, and add some biscuits to the first and second joints.  Please post a photo of the finished product!