First dovetails (and "what did I do??")

[bott]

I’ve been working on building a trim piece for my galley sink... thought it would be a good time to attempt half-lapped rabbets and dovetails (actually, a dovetail set in a rabbet… something like that).



If anyone knows what to call that dovetail-type joint, please let me know!

But, they turned out awesome… I’m very excited and can’t wait to get varnish on them!

http://staff.washington.edu/bott/d2.jpg



Here's an close up, with sealer applied (the sink is covering the upper edge with the radius cutout, don't worry:cool:):


http://staff.washington.edu/bott/d1.jpg

And setting up the cut. Only half the thickness was kept, and set into a female cavity cut in the recieving part... rabbeted dovetail? I donno... But i like it.


http://staff.washington.edu/bott/d3.jpg

[Cuyahoga Chuck]

Ka--ching!
A reprint of a 1903 handyman's book says it's called a "dovetail halved joint". I think the book was written for a British audience.

[Concordia...41]

:cool:

You're a better man than me (and a better woodworker too). ;)

- M

[Bob Smalser]

Nice work.

These are the best-kept joinery secret out there. Fast, strong and classy.

[Kitlani]

I duh know?.......I wood've thought that a dove into a rabbit wouldn't go! Sounds kinky to me.:eek:

[almeyer]

Looks really great! Craftsmanship like that is the reason so many folks like brightwork.
Al

[bott]

Look good, and classic, old timey....
Wouldn't a tenon and mortise joint could do the trick? I have used bread board jointery too. On bread board joints, no glue required, just a dowel going through the tenon...

You would probably get a better answer from Bob Smalser (who, BTW I take great pride on getting a complement from, thanks!).

My personal reason is that the pieces were 1/2" thick... my smallest chisel is a 1/4" (and a firmer to boot, not a mortice chisel). I don't think that I could hack away evenly for the mortice with leaving only 1/8" on each side without blowing out.

[Bob Smalser]

Wouldn't a tenon and mortise joint could do the trick?

http://pic20.picturetrail.com/VOL12/1104763/5536778/70922287.jpg

Sure. Plus if you pin the tenon, the piece will remain functional even after the glue fails.

Routered dovetails are merely much faster to make. Add a stable wood like H. Mahog and a flexible glue like epoxy, and the likelyhood of that crossgrain glue joint ever failing is very low. I use routered dovetails in many applications where a M/T would normally be used.

http://pic20.picturetrail.com/VOL12/1104763/2594265/36609494.jpg
http://pic20.picturetrail.com/VOL12/1104763/2594265/36609507.jpg

And not just with a router, either. I dovetail large gate and other frames because of their strength in corner joints. That barrel-handled Bosch jig saw with its tilting base quickly whips these out in workpieces too big for the tilting-table bandsaw, which is another quick way to make through-dovetails:

http://pic20.picturetrail.com/VOL12/1104763/2594265/38470804.jpg
http://pic20.picturetrail.com/VOL12/1104763/2594265/38470815.jpg

None of these joints are as pretty as Bott's, either.

[Tom M.]

Let's face it, the glue isn't going to fail.

Glue always fails.

[Tom M.]

Keep trying. You'll get the hang of it.:D

Glue always fails. Thus dovetails, and thus pinned motise and tenon, especially in a structure that flexes

I built an epoxy glued lap boat. Still holding with no mechanical back up. But that's epoxy. I hear rescorinol holds too, but you have to have a perfect joint and perfect weather, and perfect clamping pressure. Any other glue is pretty iffy.

Take a look at some old furniture, or a boat that's been left to weather. Doesn't matter how well it was put together. Over the years, joints pull apart if they aren't held together mechanically.

That's how I see it:D

[paladin]

I gots some 200 year old glue joints that have been out in all kinds of weather and ain't broke yet.......

[Tom M.]

OK, learn me Chuck. Whatcha got?

[Tom M.]

Yes, it depends on what you are building. I'm not condemning glues. I guess the real question I have is: "Who builds as if the glue will always hold?" You are the one who said that it will in a mortise and tenon. I don't 100% trust it will. Mine are pinned, or wedged, depending.

Regarding edge gluing; hey, its strong, for a glue. My benchtop is glued with just Titebond. But I have enough allthread in the corner to clamp it together when I have the time. I have edge glued many tops that are still holding. But they don't hold much. The surface area is great, and the stresses are small. (Now I usually put a spline in there.) Mortise and tenon joints are usually far more stressed.

[Bob Smalser]

How long the glue joint lasts depends on what you're trying to glue. The more brittle the glue, and the greater crossgrain forces working against the glue line, the shorter its life.

We know round tenons shrink to an oval in the dry season, reducing the glue line to two skimpy sections that eventually break when you lean back in the chair. That's the whole reason easily-renewable hide glue is still around, although some chair makers are using thickened epoxy these days with success. Hide glue lasts for centuries in long-grain tabletop layups, yet eventually breaks after less than a century in most M/T joints found in furniture, because it is brittle.

Hot phenol glues are, in turn, very flexible, but plywood wouldn't work at all if the the lams were two inches instead of a 16th thick. The crossgrain forces are tiny in veneers but huge in thick planks.

Same with trying to glue a large oak M/T joint used in a barn beam. Regardless of the glue used, a two-inch-thick tenon six inches wide and 8 inches long exerts tremendous force as the oak moves seasonally, and oak moves seasonally more than most. Even if the builders had modern glues they would have learned to pin the joints.

Glues that held up for decades in furniture often break the M/T and dowel joints when the piece is moved to an unheated shed or garage, while the laid-up top remains sound. If the piece didn't get wet, it wasn't the glue, it was the increased wood movement that broke those joints.

Boat joinery has slightly different problems, as being either in or next to large bodies of water ameliorates some of the drying with humidity. But move a boat from Puget Sound to Arizona and you'll have problems with all the wood joints, not just the planking.

How long will an epoxy joint last in a one-inch half-lap a half inch thick in mahogany, one of the more flexible glues and stable woods? Probably forever. If not, that's why you used a glue with a proven record of repairability:

http://www.sawmillcreek.org/showthread.php?t=21822

[MattL]

Beautiful Bott. I'll strive to work like you :)

[bob goeckel]

i would love to do that half lap dovetail on my canoe seats i wonder how it would hold up on a light seatframe like that?