Pegged Tenon? - Page 2 - Woodworking Talk - Woodworkers Forum
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post #21 of 35 Old 09-26-2014, 09:20 PM Thread Starter
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All very clear. Im still sort of confused on the best way to go about cutting the hole the tusk will go into. I dont have a drill press
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post #22 of 35 Old 09-26-2014, 11:25 PM
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Break out the chisels

I need cheaper hobby
etsy.com/shop/projectepicfail
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post #23 of 35 Old 09-27-2014, 12:24 AM
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Quote:
Originally Posted by epicfail48
Break out the chisels
What he said. Might drill a big hole to waste it out first.

Al


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post #24 of 35 Old 09-27-2014, 01:20 AM
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Quote:
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What he said. Might drill a big hole to waste it out first.

Al
Pft, if you wanna do it the easy way sure :P

I need cheaper hobby
etsy.com/shop/projectepicfail
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post #25 of 35 Old 06-23-2019, 01:10 PM
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I've seen this joint called a "tusk tenon" or a "keyed mortise and tenon".

https://www.bloodandsawdust.com/sca/tusktenons.pdf

The "tusk" is the vertical wedge.

The secondary mortise that the vertical wedge goes into is the "key mortise".

So I guess that means the tusk could also be called a key.

A "wedged mortise and tenon" is a different joint, it involves cutting a mortise and tenon so that the mortise is tapered, so the tenon slides easily into the mortise, but with slits cut into the tenon that you then hammer wedges into to expand the tenon while it's inside the mortise and lock it in. This is generally a permanent joint, unlike the tusk tenon, which can be knocked out for dissassembly:

https://www.popularwoodworking.com/p...ise-and-tenon/

All that said, language is seldom ever as clean, simple and organized as people would like it to be, so it's quite possible someone, somewhere in history called the one joint by the other's name, and you can find plenty of people calling the tusk tenon a wedged tenon.

I've seen a number of ways to cut mortises.

The main one people recommend is drill out the bulk and then chisel out the rest. It's annoyingly hard to do a clean job in pine, I guess the grain is too large and wavy because it tends to split. I've done that I guess 20-30 times and it's no fun so I've done a lot of looking into alternatives :-).

Other options are:

A router and a template and clamps, maybe with a chisel to clean up the corners later.

Note, a neat trick for routing deep mortises is to route from both sides with bits long enough to overlap, doing the first side a top-bearing bit that rides along the template edge, and the other side with a bottom-bearing bit that rides along the clean bottom edge left by the top-bearing bit.

A slot mortiser, which is basically a router in a specialized jig to make it easier and faster.

A hollow chisel mortiser, which is basically a drill press with a drill bit encased in a four-sided square chisel. In the videos these all work like voodoo but I'm always skeptical of demos. I've never used one, but as far as I can tell this is just a glorified version of drill & chisel by hand. I.e. the chiseling aspect is still pretty much the same, though the lever action and the drill press mechanism maybe make it easier.

Note, there are also slot mortiser add-ons for regular drill presses, but every comment or review I've ever seen of them has been negative.

A chain mortiser, which is basically a plunge chainsaw. Very popular in Japan.

Or if you want to make large mortises and have more money than sense and 3-phase power a swing chisel mortiser (which is how door factories mortise out the doorknob mortises).

Or of course a CNC router. With a CNC you could use a smaller bit and get sharper corners. Using a router normally the rule of thumb seems to be that you need a router bit that's the width you want your mortise to be, which of course means the larger your mortise width, the larger the rounding is in the corners.

The traditional way, using a straight-sided mortising chisel, check out this very cool video by Frank Klausz:


I have a nice Sorby mortising chisel and I've experimented a little with it but it's slow going in harder woods. That may because they're hard :-). Also, I'm generally doing very large mortises compared to most people (1" x 4" x 4", etc). Or I may just need to work more on my chisel sharpening skills.
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post #26 of 35 Old 06-23-2019, 01:39 PM
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So, you 've tried everything ......

I have as well.... all except a chain mortiser which is expensive, used for larger mortises in thicker doors and especially timber framing.


I bought a top of the line bench top 3/4 HP Powermatic hollow chisel mortiser thinking it would solve all my issues. It did not. It was fine for mortises 1/2" and under but even they were difficult on the first starting hole. You need to have it set up exactly correctly for it to work best. You are still pressing a square chisel down around a round hole to make square sides. This takes a lot of force and leverage is key. That's why a huge rack and pinion is a part of a hollow chisel mortiser, unlike a drill press.


I ended up using a plunge router with a self-centering jig I made myself. That went really fast and smooth and the corners were easily square up with a mortising chisel. This is my "go to method" now.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #27 of 35 Old 06-24-2019, 01:10 AM
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I didn't say I *tried* all of those, I don't have *that* much money... just that I did a lot of reading and those are the different approaches. I'm generally doing large mortises, so some of those don't really work for me (it's very hard to find a hollow chisel mortiser that's larger than 3/4", etc).

At the moment I'm in the middle of building a Matthias Wandel pantorouter, though that's pushing the boundaries of my meager woodworking skills, mainly because of the need for precision.
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post #28 of 35 Old 06-24-2019, 11:21 AM
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Here is a good demo on using a tusk tenon joint for a bench.

Gary
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post #29 of 35 Old 06-24-2019, 02:27 PM
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I've built multiple projects with pegged tenons and I'm a big fan of them because I like the look and they are incredibly strong if done right. The dining room table below is one that I built a few years back. It has two stretchers with pegged tenons at each end. I roughed out the mortice for the peg with a jig saw and cleaned it up with a template, router, and flush trim bit. The corners were cleaned up with a chisel and the angled face was done with a chisel and clamped guide block. I chose 3 degrees for the wedge angle and it worked great. If your peg is horizontal, as mine were, I highly recommend strengthening the tenon by drilling up from the bottom and gluing in a dowel. Wood is not particularly strong in shear, and with a horizontal peg, the two surfaces subjected to shear do not have a lot of area unless the tenon extends a long distance beyond the wedge. The situation is somewhat better with a vertical peg as in the previous post since the shear surface is much larger.
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post #30 of 35 Old 06-24-2019, 06:23 PM
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the tusks should be in the vertical position so that gravity will hold them in place. In most cases, as the table moves, rocks etc from normal use, the tusks should get tighter but will easily pop out with a tap or two with a mallet.
If mounted horizontally, luck hold them in place.

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post #31 of 35 Old 06-24-2019, 07:03 PM
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When chiseling pine, your chisels must have a very keen sharp edge. Pine compresses very easily when your chisel is not sharp enough. Try taking smaller shavings and a shorter depth per pass when you chisel. When doing a through mortice, chisel from each edge to finish the mortice midway through to keep from blowing out the opposite side. As you slice through the pine the summer growth (light color) grain is very soft, and the winter growth (dark color) grain is sometimes as hard as oak when you chisel through it. When your chisel is not sharp enough to shear through the dark grain...it compresses the soft grain...and it shreds its way through it instead of slicing through it. When morticing using a chisel, the wood will compress which pushes the chisel toward the wood facing the flat side of the chisel. which compresses the wood on the flat side. About finish sizing the mortice... Leave about a 1/32" of wood until you have completed the basic mortice, and then pear the last 1/32" to the line to complete your mortice. Hope this helps you.

I also agree with Tony B, about the direction of the tusk. It will stay tight.

Gary

Last edited by gmercer_48083; 06-24-2019 at 07:07 PM.
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post #32 of 35 Old 06-24-2019, 07:42 PM
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Quote:
Originally Posted by Tony B View Post
the tusks should be in the vertical position so that gravity will hold them in place. In most cases, as the table moves, rocks etc from normal use, the tusks should get tighter but will easily pop out with a tap or two with a mallet.
If mounted horizontally, luck hold them in place.
Unless you make the wedge angle two big, it is friction that holds the wedge in place. In other words the wedge is self-locking (a standard problem first year engineering mechanics students do i.e. calculate the angle range for which the wedge is self locking.) Any contribution one might get from gravity with a vertical peg is negligible in comparison to the other forces involved. Sorry to get all technical but the orientation really doesn稚 matter.
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post #33 of 35 Old 06-27-2019, 11:04 PM
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No matter how your calculations work out, we are dealing with wood. The coefficient of expansion of the tenon walls and the wedge are different. The temp. and humidity changes compounds that problem. Aside from the advanced mathematics involved, which most of us cant do, consider this.... as people move and lean on the table and bump the table, over time, the wood on the tusks and points of contact on the mortise will compress. This compression will lead to a loose tenons. In the traditional method of vertical tusks, if the tusks become loose, gravity will make it slip further down into the mortise and re-tighten itself.
As for the horizontal tusks, luck is what will hold it in place considering the wide end of the tusk is heavier than the narrow end. The unbalance of weight will ultimately lead to the heavier end falling on the floor. At best, a wabbeling table base.
For thousands of years, or at least many hundreds, craftsman have been using tusk tenons successfully Most of them couldn't write or spell their own names and certainly couldn't do the engineering math. They simply made a vertical tenon with one side sloped to create a wedge shape. Then they did their best to duplicate the same angle when making the tusk (wedge) the same way I make mine. If it comes loose, i will never know because gravity will be on my side and the joint remains tight. Tight enough that I need a mallet to bump it out of position.
Then again, I may just be lucky.

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Last edited by Tony B; 06-27-2019 at 11:13 PM.
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post #34 of 35 Old 06-28-2019, 12:31 AM
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Guess I知 a really lucky guy - wish it carried over to lottery tickets. If your saviour in all of this is the weight of a wedge that might be measured in ounces compared to forces that are three or four orders of magnitude bigger then go for it. I知 not saying vertical isn稚 good, I知 just saying horizontal is not a problem either and the difference in the forces involved is negligible. Frankly I don稚 care to drag this out anymore - as with anything, you are free to believe what ever you want. I値l continue to do horizontal because I like the look and have never had a problem and neither have the many tens of thousands of other builders over centuries. You do what you want and I値l do what I want and we値l get along fine, maybe. That's more up to you than me.
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post #35 of 35 Old 06-28-2019, 10:15 PM
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I like horizontal because it means the mortise is a lot shallower and easier to cut, and I don't think I'm that good a woodworker yet :-).

Having said that, I use this for furniture that is in odd circumstances, uneven ground that means there's a lot of odd directional force. For that, I kind of wonder if the double horizontal tusks works better.

The main reason you use two horizontal tusks, according to what I've read, is because a single tusk ends up being a pivot point. But I suspect two horizontal tusks also ends up having a lot of surface area pressing against the wood around the mortise in both dimensions, keeping the joint stable.
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