Until a YouTube vid the other day, I’ve never seen this before: the guy joined two pieces together by drilling matching holes in the two, hammering nails half way into one piece, then cutting the heads off, lining it up with the other piece and hammering it home. It’s probably done all the time, because I guess it’s kind of obvious. New to me though. Is there a name for it?
Are you sure he wasn’t doing that just to mark the centres for holes drilled to take dowels? Because that sounds like it would be quite a weak joint if it’s just nails like that.
No just nails and glue. I’m thinking it would be ok for some more decorative work where strength wouldn’t be as much of a factor.
Maybe, or if the glue is actually providing a significant amount of the joint strength once cured.
I’ve never heard of the technique before; since it seems similar to a dowel joint (but with cut nails in place of the dowels), I would have thought it might have a dowel-related name, if it has a name at all. It sounds like a terrible bodge, if only because you have no real control over how deep into each side the nails will penetrate, if you’re hammering on the outside of the wood.
I’m with @Mangetout
I assumed we were talking about this:
https://www.familyhandyman.com/article/nail-dowel-centers/
I don’t even know how well wood glue would stick to a nail – IOW, how much strength the adhesion part would provide.
If it’s a ridiculously low-stress joint, then … yeah … okay.
Wanna’ post the video and the time (min:sec) where we can see it ? I’m curious.
Yeah, I suppose in that specific application (the joint will not experience any stress at all as it’s affixed to something else), it seems to work, It’s really just an inferior version of a dowel joint though - I’m actually surprised, after he went to all the trouble of measuring, marking and drilling for what would be a perfect dowel setup, he then used nails. It’s a bodge. I guess if you don’t have any dowels, it sorta works.
Yeah. I think it was mostly as an alternative to dowels or biscuits, and primarily to get good alignment of the boards.
Not a lot of mechanical strength provided (I would guess), nor needed.
Also: he didn’t properly square off the end of the short piece of timber - you can see that it doesn’t meet flush with the long piece when he hammers it down - that’s the weakest part of the whole thing because even though he smooshed a bit of glue in there, it means at best a thick glue line inside the joint, which might be quite weak.
‘Gluing Brads’ and a butt joint. Or a butt joint with gluing brads. You normally use brads or pin nails inserted from the outside, but cutting the head off a nail is a way to make a headless nail, and inserting from the inside is a way to work with thicker pieces of wood. Another way to work with thick pieces of wood is pin just the corner, by driving a nail at angle through the end.
Normally you use thick pieces of wood for strength, and butt joints for cheapness, and if you want to make a butt joint, you drive big nails through it.
Maybe didn’t want the nails visible. The glue holds it and the nails are primarily to hold it until the glue sets.
But he goes ahead and drives big screws through the top.
Glued wood joints, if made with proper wood glue properly applied, are extremely strong—often stronger than the wood itself, though it does depend on joint geometry too. See Matthias Wandel’s testing (and more in the “see also” links at the bottom).
I didn’t notice that the first time I watched it, but you’re right. That doesn’t look like a proper glue joint to me.
He did pre-drill the holes, so that provides a bit of depth control. It looked like the holes were still a bit smaller than the nails (because he had to hammer), but it’s still probably easier for the nail to slightly widen the hole on the side with depth remaining than to deepen the hole at full width on the side where it’s bottomed out, even being pointier on that end. I wouldn’t mind seeing an X-ray picture or a physical cross-section of such a joint to be sure, though.
The glue is to attach the two pieces of wood directly to each other, not each one to the nails.
That’s what I thought, but then he clamped it. Maybe they’re more to hold it in alignment, rather than to hold the pieces pressed together? But he did have to hammer to get the nails into their holes, so I’d expect them to provide more than zero strength against getting pulled back out.
I noticed that, too.
The reason I speculated about glue sticking/not sticking to a nail was that seasonal movement of the rest of the board could leave the nails very loose in those once-tight holes, so any added strength to the joint could easily vanish with seasonal movement.
[I don’t know where this guy is. Maybe the humidity is dead stable all year long, but … if not … Dowels or biscuits would move with the wood, +/- difference in species and grain direction – in any case, more than nails , and that’s not counting some absorption of glue with dowels/biscuits.)
Which was a piece of why I really figure it was either a misguided (if well-intended) effort to add strength, or just about alignment.
Drilling the nail holes is so the wood doesn’t split. Could have done clamping as an added measure.
Good point.
Yes. Did anybody say/imply otherwise, or that he shouldn’t’ve pre-drilled? I don’t see how drilling the holes for the nails and clamping for the glue are alternatives and/or supplements to each other.
You haven’t seen that before because that guy is a hack.
ETA, he’s not wearing a mask for dust protection, he’s wearing it so nobody recognizes him 
ETA r2. If you want to join wood in that way, you use mortise and tenons. Given how wide the cross members are, you would use a centered 4" wide tenon 2-3" deep with a haunch in a groove on either side.
Many mentioned that they thought the drilling the nail holes were for alignment/guiding. Normally you don’t need to clamp something if you nailed it. I can see someone clamping in addition to nailing for extra certainty even if not necessary. The headless nail might not provide the holding power of a regular nail.
This. The nails help keep the boards from slipping while they are clamped up. Totally unnecessary if it was properly constructed. He ends up driving a bunch of screws through the top to put it all together anyway.
Always clamp a flat glue joint (or any glue joint, if you can) to ensure that the pieces are as tight together as they can get and stay that way until the glue dries. If there is a slight warp to the surfaces this ensures they are tight together. Nails don’t necessarily do the job, since the can slip in the holes. screws are more reliable this way, but then the whole point of glue may be to avoid unsightly screw heads.
I recall a discussion of aircraft glue (as used to make old fashioned wood and canvas aircraft) that said tests with cured glue joints (and evidence from crashes) often showed the joint so strong that the wood itself would splinter beside the joint before the joint failed. Glue be strong.
Drilling a pilot hole for relief is a good trick to avoid wood splitting if the wood is very thin where the nail goes in. But the whole point of the trick is to align two boards precisely, I presume - so drill and insert the nails in one board, line it up with the other and hammer to create a dent to tell you exactly where to drill the corresponding hole(s) - then drill, glue and hammer and clamp. The nails at most prevent cross shear along the joint along with alignment (like dowels or biscuits also do), and the glue provides the real strength. However, for best strength, dowels or biscuits will also hold glue and provide joint tension strength.