Monday, October 14, 2019

American Trestle Table - Part IX - Solid Wood Buttons by Hand

Or: Practice Cutting Tenons While Making Buttons.

Modern technology has given us many ways to attach a table top to a base. Traditionally a table top is mounted to a table base using buttons, which allows for seasonal wood movement very elegantly.
A button that holds on a table top.
Making buttons with a table saw is easy, but you either have to use plywood for a strong button, or make a million extra cuts into the end grain in order to make the grain go front to back. You might be tempted to do a quick and dirty job with a piece of solid wood, but if the grain goes side-to-side, your buttons will break and your top won't be  mounted for long.

I suggest you go ahead and try it with hand tools. It isn't that much more difficult, and I think the extra time used doing it this way can be justified: making buttons this way practices skills you will need in cutting tenons by hand - one of the most difficult jobs to do with hand tools. I have decided that next time I make a table, I'll make the buttons before doing any of the mortise and tenon joinery as a refresher course.

What is a button? It's just a little block of wood with a tab. The block is screwed to the table top and the tab goes in an elongated mortise on the base.

They can be any size, but making them consistent means you don't have to fit each button to an individual mortise on the base. Mine are 3/4" thick and 1 1/2" long, with a 3/8" tab (3/8" notch) that is 1/2" long. The width can be anything from probably 3/4" on up. Mine are 1 1/4" wide, because that's how thick the board that I sawed them from was.
Sawing 3/4" button stock from a 5/4 board.
Make your stick as perfectly as you can. This is good practice. It's not the end of the world if your buttons are different thicknesses, but other parts of your table might need more precision. This is a perfect opportunity to practice thicknessing stock by hand.

Once your stock is ready, plane chamfers that will be on the outside of the button. Making these two chamfers now will make your buttons look more consistent than if you do them at the end. There are a total of five chamfers that I made on my buttons, and the two main ones were done at this stage.

There is only one thing on a button that needs to be relatively precise, and that is the distance from the table top to the underside of the button's tab (in my case, 3/8"). Accurate layout is key. set a marking gauge to 3/8", and register it from the bottom side of the button. Even if your buttons wind up being slightly different thickness, this measurement will ensure all the buttons hold your table top on nice and tight. Set this marking gauge aside and do not adjust it again until all of your buttons are completed.

The very first button has the cross cuts marked with a ruler and a marking knife. After that, use this first button to mark the others so they all are the same.
Accurate layout is the key.
Accurate saw cuts are now important. One trick to assist is to make a little trench in the waste with a chisel. A crosscut saw now will track in that trench making this cut a breeze.
Notice that my "trenches" go opposite ways. I'm only carving away the waste.
Only make the crosscut for the tab at this point. Leave the button attached to the rest of the stock. This will help in removing the waste for the tab.
A saw tracks in this notch very nicely.
Once the crosscut is made, just like a tenon, remove the waste.
Sawing the waste.

Alternatively, split the waste. Paul Sellers has a nice YouTube video on how to do this.
Once the tab is done, then you can cut the button to length. In reality, the button will work no matter how ugly this crosscut is. However, try to do your best work for practice. Making a crosscut perfectly square is difficult, and a good skill to have.
Cut to length.
If you choose, you can clean up the back of the button with a shooting board. Here also is where you finish the chamfers: three on the backside of the button. This will leave a rounded surface on every corner that could be touched once the button is installed.

Regardless, take time now to square up the crosscut on the remaining bit of the stick. The rest of our buttons will come from this stick, and a square tab end will aid in looking neat (but is not strictly necessary).

Now we have a button that only needs a hole for the screw. The hole should be a little larger than the screw threads, so a screw can be pushed through the hole freely. I used counter sunk screws, so I added a countersink for the screw head to sit flush, and a tiny countersink on the table top side just to clean up the surface and ensure a stray fiber doesn't get in the way of the button seating flush to the table top.
My hand-powered countersink.
All that needs to be done now is to repeat the process for as many buttons as you'll need. I made twelve for my table, which is overkill.
Do they really need to look exactly the same? No, but making them this way builds many skills that are needed for other things.
To mount the table top, I made mortises in the corresponding parts of the table, drilled pilot holes in the top (ensuring not to drill all the way through), and screwed them in.
Done!
I think that solid wood buttons add a little flair to a boring part of the project. No one will ever comment on them, but you know they are there and that they were done right. I think the biggest benefit to using them is the skills you will hone. Face it: no one likes to practice things like tenons in scrap. Here you can practice making a dozen tenons exactly the same, and use the offcuts for a practical part of your project.

13 comments:

  1. Helpful! Quick question: Should one expect to lift and move a table by the table top after it's been assembled in this way?

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    1. I wouldn't expect it to be a problem. If there is far to go, the buttons can be carefully unscrewed and then re-attached later.

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  2. It should not be a problem if the screws are deep enough in the table-top.
    Sylvain

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    1. Hey Sylvain! Yes, one should make sure the screws are long enough. I used 40mm screws for a 40mm top along with 3/4" (18mm) buttons. They go in a little more than half way through the table top in my case. Plenty.

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  3. Replies
    1. Yes! Actually, I just finished it. Stay tuned for the grand reveal!

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  4. Brian,

    Good ticktock and really nice buttons. I'm ashamed to say lately I've been using "Z" fasteners I guess I'll have to go back to buttons. You have reminded how much nicer they can be.

    ken

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    1. Thanks, Ken! I never really knew that I had so much to say about simple buttons, but once I realized I was practicing tenons, I figured I'd have my say.

      Cheers!

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  5. Nicely done, Brian. One question for you, though. If the depth of the rabbet (that forms the tab on the end of the button) is 3/8", how far from the upper edge of the apron do you place the mortise? Is it 1/16" more than the rabbet depth? 1/8"? I've used this technique once before, but don't remember the offset I used.

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    1. Hey Matt! Thanks for the comment!

      It's not important for the mortise to be tight like a regular mortise, but the bottom of the mortise needs to meet the bottom of the rabbet very tightly in order to hold the table top snugly (not what you asked).

      I tried to make sure that mine were either perfectly flush, or just a tad over so the button holds the table firmly. I think if you offset too much you could risk breaking the button (or more likely the screw), or prevent the table top from sliding laterally with regular expansion and contraction.

      Short version: not much of an offset at all, but for sure not an overhang.

      Does that help?

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    2. Yes Brian, very much. Thanks a bunch.

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  6. Well done, nice job on these buttons. Truly the classic way to attach a table top. Can the table be lifted by the top? When was the last time anyone saw someone moving a table NOT by the top?? Yap, it will hold.

    Bob

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    1. Hey Bob! Thanks for the nice comment. The way I've constructed this table,there are eight screws holding the base to the top when it is lifted this way.

      Cheers!

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