Buttons

[PaulH]

Please forgive this basic question , but if buttons are designed to allow for movement in a table top, how do you prevent the table top from moving around (albeit slightly) when the table is lifted, bumped into or whatever?

As you can tell, I'm relatively new to this, but learning a lot from reading this forum, which I do daily! Thanks to everyone.

Paul.

 

[Offcut]

PaulH,
I haven't used buttons before but I would think that the design allows you to screw them into the table top sufficiently to not allow movement when handled and bumped, but will allow movement in the wood across the grain which would happen and a rate not usually detected by the eye. If you fix it rigidly - screws etc there is no allowance for movement.

Someone will correct me if I'm wrong

Andy

 

[Colin C]

Offcut, you are correct

 

[engineer one]

the buttons are indeed designed to allow for the table top with grain in one direction move with natural expansion and contraction, against a base which has grain in a different direction.

since the buttons fit in the groove, and are screwed, they will allow for the wood movement, whilst stopping the top being moved in the day to day jumble of life.

i guess the real answer is that it has been done for years, and no one has come up with a better solution, just different, like metal tongues.

but the engineering thought is that you have buttons in all four sides, so any movement by knocking is likely to be counter acted by their being an opposite movement because of their number.

hope i have not muddied the waters too much.

don't forget to orientate the buttons and their tenon to take advantage of the strength of the wood, and not include a potential breakage point at the corner of the tenon.

all the best
paul :wink:

 

[Waka]

I need touse some buttons on the top of my Comp piece, never used them before, anyone got any pic's thay might find useful.

 

[PaulH]

Thanks for the responses above.

Paul - If you take a typical rectangular top sitting on a frame with the grain running parallel with the longest side, then the "long" sides will be resting on a rail that has grain running in the same direction but the "narrow" ends will be perpendicular. So should you only use buttons on the "narrow" end (grain perpendicular) or on all four sides? If only 2, can you fix the top rigidly on the other 2?

Also, I'm not clear what you mean regarding the orientation of the buttons and their tenon to take advantage of the strength of the wood - can you please expand?

Thanks again to all.

Paul.

 

[engineer one]

ok in most tables i have taken apart, there are always four buttons,
or a similar device.

as for the grain orientation of the button, remember what you were always told about tenons, that where the tenon is cut you should make sure that you have the grain lengthways other wise there is a chance of the tenon breaking at some time in the future because of the bending moment.

a lot of people these days tend to make their buttons by routing the thin piece on a longish piece of wood, and then cutting them of individually with either a chop saw, or the bench, that way they are all the same depth.

does that help???
paul :wink:

 

[Steve Maskery]

For a quick an effective way to make buttons, go to the Resources area of my site.

</plug>
S

 

[Alf]

I need to use some buttons on the top of my Comp piece, never used them before, anyone got any pic's thay might find useful.

Few here (overkill? Who said overkill...? :lol: ) Also here and a few buttons in use here (okay, so I just like some of the pieces if I'm honest...).

Cheers, Alf

 

[Waka]

Alf

Thanks I get the picture.

 

[engineer one]

would you believe it that today on discovery real time 252
norm was making an older style round table, and he used buttons.

what he did say was make sure that your slots do not go all the way into the corner to ensure they do not weaken the tenons on the legs.

i think it was from the 1998 series.

paul :wink:

 

[PaulH]

Paul - yes that is helpful regarding the orientation question. Thanks.

Paul.

 

[Sgian Dubh]

Paul, there isn't a lot of movement as others have said, and you've got the picture of buttons and how they work. But here's how to fix the top at a particular location.

Let's say you want the top to expand and contract about the centre point and, that the long grain of the top follows the long rails. Make a stopped groove at the centre point of the short rail on the inner face. If, for discussions sake, the button is 35 mm wide, make the length of the stopped groove 35 mm too. This fixes the button position and fixes the centre point of the table/cabinet top.

Make any additional (stopped?) channels for the tongue of further buttons on the shorter end rails longer than the 35 mm width of each button and centre the button in the length of the groove to allow for movement. The further each button is from the centre point, the more you need to allow in the rail groove length for movement.

Of course you can fix the position of a table or cabinet top at other points, such as at the front or at the back using this (and other methods) causing all movement to be towards the opposite edge of the table top.

You might, for example, fix the top of a hall table that stands against a wall at the show front side allowing all expansion and contraction to occur towards the rear-- the wall side. That's just an example, but you could think of other situations where you might reasonably choose the fixed point in the table top width about which expansion occurs. Slainte.

 

[PaulH]

Perfect - I understand now.

Thanks to all who replied to my query.

Paul.