Table leg tenons - to pin or not to pin

[Bill Brush]

I'm working on a coffee table and the legs and aprons are joined with mortise and tenon joinery. If you want to see it, pictures are here: http://www.sawmillcreek.org/showthre...ly-started-WIP

I've vacillated about cross-pinning the tenons ever since I started planning this project, but now it's time to make a call. The frame will be glued up tonight, so it's time to make a decision.

The tenons are 2 1/2" wide, 3/8" thick and 7/8" long. The mortises are 1" deep to allow for movement. If I pin them it would be a 1/4" pin in the center of the tenon.

So, what are the opinions? Does it make the joint stronger? Is it pointless extra work? Same color wood, or contrasting wood? (The finish will be Waterlox) Flush or proud of the surface? Straight or draw-bore?

[glenn bradley]

I would say it is up to you. In joint strength tests non-pinned were a bit stronger but, not enough to make me skip the pin as an assembly aid or as an aesthetic element.

[Jim Cunningham]

I can see no need to pin a joint on a table like that

[Harold Burrell]

I would say it is up to you. In joint strength tests non-pinned were a bit stronger but, not enough to make me skip the pin as an assembly aid or as an aesthetic element.

WHAT?!!! Seriously? I would have thought just the opposite.

[Jim Matthews]

It won't make the table stronger - anyone dancing atop will still fall through.
The only advantage pins provide is holding things together while the glue sets.

It won't improve the look of the table, which is already clean.
If you use liquid hide glue, you'll have more time to get things assembled.

Otherwise, you might consider gluing the legs together at each end, and joining them with the long rails tomorrow.
Keeping this many joints straight at once will require two steps, or two sets of hands.

Gary Rogowski wrote an article about this, and half way down mentions this.
I like to put a line of blue tape along each joint to catch squeeze out.

I saw Dave Marks do this, repeatedly on his TV show.

The best time to find out you need more clamps is before you apply the glue.
Did you already walkthrough a dry run?

[Van Huskey]

The table is too clean for pins in my view.

[Bill Brush]

It won't make the table stronger - anyone dancing atop will still fall through.
The only advantage pins provide is holding things together while the glue sets.

It won't improve the look of the table, which is already clean.
If you use liquid hide glue, you'll have more time to get things assembled.

Otherwise, you might consider gluing the legs together at each end, and joining them with the long rails tomorrow.
Keeping this many joints straight at once will require two steps, or two sets of hands.

Gary Rogowski wrote an article about this, and half way down mentions this.
I like to put a line of blue tape along each joint to catch squeeze out.

I saw Dave Marks do this, repeatedly on his TV show.

The best time to find out you need more clamps is before you apply the glue.
Did you already walkthrough a dry run?

Oddly enough I literally just finished doing a dry fit run. I was thinking "Maybe I should glue the ends together then do the long aprons separately." I even put the tape on the legs to catch the glue drips. Wow, that's weird.

My main thought with using a pin was that it wouldn't matter if the glue joint failed in some way, the table will stay together. As I'm learning more about wood glue I think this is an unrealistic concern. I think I'll forgo the pins on this one. Thanks!

[Chris Friesen]

WHAT?!!! Seriously? I would have thought just the opposite.

Adding the pins means a reduction in surface area for glue to bond. As long as the glue holds, it will be stronger without pins. In a few decades or centuries when the glue fails, it would be stronger with pins.

Personally I would have made the tenons as long as possible and then pinned it--1" is too short to pin in my books, though others might disagree.

[Mike Cutler]

I wouldn't pin it. If you didn't plan for it in the beginning, you'd just be setting yourself up for a mistake that could cost you time and effort already spent.
At most I'd install table corners underneath if I was worried about long term joint integrity.

Nice work.

[glenn bradley]

WHAT?!!! Seriously? I would have thought just the opposite.

I know, I was surprised as well. As Chris pointed out; interrupted glue area. Under the stress test the tenon split along the weakened length where the hole interrupted the fibers.

Capture.JPG

[Pat Barry]

Glenn, Those results don't look at all like you would expect therefore I don't believe them. For example, the miter is better than the wedged M&T? That is incredible and unrealistic. If that was anything better than the worst of the bunch it is plain unbelievable. What was the source of that data again?

[keith micinski]

I don't see strength being concern at all with that tenon. I make that exact table all of the time and I use 1/4 wide tenons and I actual do test everything out by getting up on it and jumping around. I sometimes like a pin for aesthetics maybe even a brass one. I like that table a lot but I usually like to use some contrasting wood in my tables so I think a pin may actually be a nice touch. That having been said no pin would not hurt that table at all because of the beautiful grain selection.

[Peter Quinn]

I think pins were essential in the best quality work when hide glue was the only option. Seems it didn't always hold up over decades like modern glues, so the mechanical connection was an essential backup. And a draw bore makes a nice clamp to boot. Metal used to be very expensive, thus clamps were precious and perhaps more scarce than we realize today. But if you have plenty of cheap (relatively) modern clamps and PVA glue, the pins will just weaken your tenons. Yet they still have some emotional appeal, no? You could certainly put them in from the back if you would rather not see them for design reasons, so that is IMO of little concern.

So pins or no pins? Pretty much your choice, because those tenons are going to be more than strong enough either way. I have some 100+ year old windows in my home I have been slowly restoring, all are pinned M&T joints, on many the glue has long since failed, but the pins hold the joints strong even when considerable rot has occurred. So if you are going to leave your coffee table out in the rain, definitely pin those tenons. Otherwise, trust your instincts.

[Paul Symchych]

Amazing coincidence. I am about half way through a virtually identical table built in lacewood. Dimensions are different because that is a hallway entry table but all of the details are identical.
I usually pin M&T joints because I like the look.
I haven't broached the question with them and most people don't care or notice but am inclined to use something subtle like walnut for the pins to provide a bit but not too much contrast to the lacewood.

[Bill Brush]

Personally I would have made the tenons as long as possible and then pinned it--1" is too short to pin in my books, though others might disagree.

If I had made the tenons longer they mortises would have intersected, something I wanted to avoid. The legs at the top are only 1 3/4" square. (They taper to 3/4" square at the bottom.)