Through tenons

[Greg Guarino]

I'm between projects at the moment and I'm contemplating the next one. I try to design in a new technique here and there to improve my skills. I've been flirting with the idea of through tenons. Given that I have yet to make even a blind mortise and tenon joint, this may be premature, but I'm tossing around ideas in my head.

I've got some ideas about how I could make tenons given my limited tool set, and I figure a plunge router (which I don't have yet) and a template would take care of a *rounded* mortise. I'm wondering how you guys square off the mortise. I assume that unless you have a dedicated mortising machine, you use some sort of chisel(s), but what kind?

Do you use anything special, or just regular chisels? I've seen a corner chisel, if that's the right term. I don't mean the kind they sell for hinge mortises. It's a fairly long chisel with two cutting edges at a right angle. I also see square chisels, which look very much like the hollow chisels that are used in dedicated mortising machines, but with a handle to be struck with a mallet. Lastly, I've seen mortising chisels, which seem to be twice as thick as regular chisels.

Thoughts?

[John McCoy]

Greg Guarino wrote in news:mdv0o8$gf9$1@dont- email.me:

Regular chisels for me. If it's a thru mortise, cut in from both sides so the cut is clean at the edges. If the chisel strays a little in the middle of the mortise it's no problem.

Corner chisels look like a neat idea, but they're hard to find and hard to sharpen, so a regular chisel is just simpler.

John

[Scott Lurndal]

For tenons, you can't beat a sharp backsaw and a shoulder plane.

A mortising chisel is both necessary and sufficient.

Mortising chisels are much beefier than standard bench or beveled chisels (they're designed to pry the chips out of the mortise).

[dadiOH]

Step #1 Decide whether you want square corner or rounded mortices.

Step #2 Cut the mortices. If round, a plunge router works fine. Cut the tenon square, use 1/4 round router bits to round off tenon edges. You can't use the router to get all the way to the shoulder but what remains can be done by hand easily with a knife, rasp, whatever. You could also use loose tenons, easiest of all. Size the tenons according to the 1/4 round over bits available; i.e., if tenons are 1/2" thick, use 1/4 radius bit; if 3/4" thick, use 3/8" bit; etc.

If square, you can remove most with a drill bit or router, squaring up with a hand chisel, knife or file. You could also saw out the corners with a scroll or coping saw. You could do the whole thing by hand as John explained (there are special, longer mortising chisels for that purpose). You could drill them square in a drill press with mortising bits...those are a bit in a hollow chisel...the bit removes most, the chisel shears off the corners as you lower the bit, same as a dedicated mortising machine. On a drill press, you need a fence and a mortising attachment to hold the work solidly in place.

[John McCoy]

"dadiOH" wrote in news:mdv7n2$fte$ [e-mail]:

OP was speaking of thru mortises, so he'll probably want them square. I don't think I'd do a rounded mortise unless I was going to do a very long tenon, and put a peg thru it on the outside.

I think it was actually Scott who suggested a mortise chisel. Cutting mortises that way takes a fair bit of practice.

While all the methods you list are good, for someone starting out with limited tools I would go with either a router and template, or drilling a sequence of holes, and in either case using a normal bench chisel to clean up.

John

[Swingman]

Something else to think about if you want to do floating tenons with a router.

It's possible to do floating through tenons, with the visible part square, giving you a traditional through tenon look.

Because I use a Multi-Router for most of my floating tenon joinery, I've done this a few times:

In the one shown I did inset the square part in the stile/leg using a dedicated mortising machine for a shallow (1/4") square mortise, but you don't have to.

Just make the visible square part of the tenon long enough for the look you want, insert in both parts, glue and pin the joint with a contrasting pin, and Bob's your uncle.

The part is that difficult to make once you get started, and there is more than one way to skin the cat to fabricate them.

I make them square, then round-over the square edges of the floating tenon with a pattern makers file to fit the round mortises cut in the stock with the Multi-Router.

Traditional look and strength, modern tools...

[Leon]

AND to expand on that a bit.... you can also do trough tenons and sand them flush with the piece that they are going through, the exposed side. Don't worry about appearance. Cut a false tenon to glue over the actual flush sanded through tenon. It can be slightly larger than the actual mortise to cover the "real" joint lines.

Great idea! And affords the sticking out portion of the tenon to be a longer length than my suggestion above.

[Greg Guarino]

Well I'd probably never have thought of that. But for the uninitiated, what's the advantage over the traditional tenon? Just that the rounded mortises are easier to make, I assume?

[Leon]

Absolutely and the over sized square portion that is visible does not have to fit into a mortise.

[Greg Guarino]

I was thinking about that. Karl's drawing shows a loose tenon that does need to be inset in a mortise that is squared off, at least to a certain depth. I see that you could do away with that, by making the "square" part only as thick as the visible section. But it strikes me that that would make for a very thin edge, unless the visible section is to be thicker than usual.

[John McCoy]

Greg Guarino wrote in news:me552k$gj5$ [e-mail]:

That would be what I'd say. You can cut the mortise with a router, or by drilling the ends and a series of in-between holes on the drill press (and chop out the bits between with a chisel). Either of those are available to someone just starting in woodworking, who wouldn't have a mortising machine, mortising attachment for the drill press, or old style mortise chisel.

The disadvantage is that it's obviously machine-made. If the tenon is visible, and you want to emphasis your hand- craftsmanship, then it has to be square. So you either make a square mortise, or you do as Leon suggests and make a faux tenon as a trim piece (which, honestly, to me sounds like more work than making the mortise & tenon square).

John

[Swingman]

Nope, You don't need to do that all.

As I said, I just do it that way on occasion.

[Leon]

Yes, the visible part would be larger to your liking and would cover and hide the actual mortise and tenon. For strength, floating tenons do not have to a perfect fit except with the cheeks of the tenon being the same as the mortise. Length is not so important, you have plenty of contact glue surface on both sides of the tenon. Floating tenons typically do not completely fill the mortise anyway, this gives you wiggle room. In fact the Festool Domino has three width settings for it's fixed width Domino tenons. Exact fit, and two progressively wider than exact fit mortise settings.

[DerbyDad03]

..and with a little creativity regarding the shape, you could really have people scratching their heads as to how you got it "through" the wood. ;-)