Worktop bracing

[Designer1]

What's everyone's thoughts on using metal braces on large widths of worktops?

I've had a pine top bow on a piece I made about a year ago now. Luckily it is just a personal piece. It's made from 20mm PSE redwood, a width of about 400mm front to back and about a meter wide. It's bowed about 4mm up at the front over the 400mm.

My personal thoughts are that the wood wasn't sufficiently dry when it was milled and joined together and the top has dried more than the base which has caused it to bow. I'm going to be making another one from 36mm rough sawn milled down to around 30mm thickness and router in a channel for some 5mm flat bar underneath with some oval slots in to allow for expansion and contraction of the wood, then put in a threaded screw through the oval hole in the flat bar into an insert nut in the wood.

What's everyone else's preferred method for making worktops?

I have made a fair few before but usually from more stable hardwoods such as euro oak which haven't moved at all. Perhaps it's just because it's pine and tends to move a fair bit anyway.

Thanks, Designer 1

 

[baldkev]

I resized a table for a customer once, pine, 40ishmm thick and it was maybe 900 x 2m... they wanted to add about 200mm, so i used 4x2 pse, thicknessed it, cut the too down a glue line in the middle, and added the new bits. The original had a 25mm x 4?mm angle iron mounted underneath near each end and it was rebated into a 5mm slot so just the thickness of the plate was visible. Seemed to have worked so i did the same....

 

[Designer1]

I resized a table for a customer once, pine, 40ishmm thick and it was maybe 900 x 2m... they wanted to add about 200mm, so i used 4x2 pse, thicknessed it, cut the too down a glue line in the middle, and added the new bits. The original had a 25mm x 4?mm angle iron mounted underneath near each end and it was rebated into a 5mm slot so just the thickness of the plate was visible. Seemed to have worked so i did the same....

Thanks just what I wanted to hear, it's a good job you realised the metal flat bar was there before you cut down the glue line

 

[Designer1]

Angle iron*

 

[baldkev]

Yep, i had taken it off the base and carried it outside

 

[Cabinetman]

It sounds like you know your business, but just to check, how wide were the planks you joined together, and did you reverse the boards each time as in cups and bridges? Ian

 

[baldkev]

Hi ian,
Yes i alternated end grains
I found a finished picture from their house, but unfortunately have none of the in progress to show angle iron or end grain ( plus the lighting is poor ). The whole top was beltsanded and refinished in osmo with the white tint. We decided not to try to stain down the new bits in case it looked worse. I had suggested tea staining, but customer said no

 

[baldkev]

Oh yep, the width. The original table was about 900 and i added 2 pieces of 4x2 planed, so total width just under 1100 now

Edit just to add that i used biscuits to align the tops nicely on clamp up and used the angle iron supports to aid keeping flat during glue up. I had a 4' level clamped across the grain one end and a 3 foot the other end, centrally. I could have used a 6, but the original timber would have been 20 plu years old, so stable.

 

[Jacob]

What's everyone's thoughts on using metal braces on large widths of worktops?

I've had a pine top bow on a piece I made about a year ago now. Luckily it is just a personal piece. It's made from 20mm PSE redwood, a width of about 400mm front to back and about a meter wide. It's bowed about 4mm up at the front over the 400mm.

My personal thoughts are that the wood wasn't sufficiently dry when it was milled and joined together and the top has dried more than the base which has caused it to bow. I'm going to be making another one from 36mm rough sawn milled down to around 30mm thickness and router in a channel for some 5mm flat bar underneath with some oval slots in to allow for expansion and contraction of the wood, then put in a threaded screw through the oval hole in the flat bar into an insert nut in the wood.

What's everyone else's preferred method for making worktops?

I have made a fair few before but usually from more stable hardwoods such as euro oak which haven't moved at all. Perhaps it's just because it's pine and tends to move a fair bit anyway.

Thanks, Designer 1

Main thing is to not hold it tight down but to let it move. The trad method with table tops is the "button"- slightly loose in a slot with room to move. 1000s of examples on line, this is just one How to Attach a Table Top with Traditional Wooden Buttons | Popular Woodworking Magazine
You don't need many - just enough to keep the top feeling solidly in place and strong enough to lift it by the top. Small table 4 might do it.