Tenon w/router?

[Robin Cruz]

I saw a snipet online of Norm Abrahms show 2011 for an outside chair (not the whole show). For the rear legs, he used an mdf template with router openings to make the mortises.

How do you make the tenons that have round sides? Or is he using loose tenons?

My project is a rocking chair. Is using loose tenons going to be less strong then a normal mortise/tenon approach?


Any thoughts?

[Greg Robbins]

Make a normal tenon and round over the edges with a rasp.

[Mike SoRelle]

I've seen Nahm use a router to make mortises a couple of times, but he usually squares up the corners with a mortising chisel afterwards (this is actually how I do motises alot of the time)

I've seen some guide templates for cutting integral tenons using a router, but I never tried it.

I think the general consesus is a tenon is a tenon whether it's integral or loose, the only caveat being that with a loose tenon joint you have two chances to do something to screw up the glue joints (not enough glue, overclamped, etc) instead of one.

Mike

[Robin Cruz]

Thanks. Sounds like loose tenons would be a lot easier then.
Does the glue type matter that much for a chair? Will yellow glue or Gorrilla poly make a strength difference?

I've seen Nahm use a router to make mortises a couple of times, but he usually squares up the corners with a mortising chisel afterwards (this is actually how I do motises alot of the time)

I've seen some guide templates for cutting integral tenons using a router, but I never tried it.

I think the general consesus is a tenon is a tenon whether it's integral or loose, the only caveat being that with a loose tenon joint you have two chances to do something to screw up the glue joints (not enough glue, overclamped, etc) instead of one.

Mike

[Mike SoRelle]

Thanks. Sounds like loose tenons would be a lot easier then.
Does the glue type matter that much for a chair? Will yellow glue or Gorrilla poly make a strength difference?


In an effort to not restart that holy war I'll direct you to this thread http://www.sawmillcreek.org/showthread.php?t=83665 the original question related to dowels on chairs, but your question is essentially the same since the dowels are just loose tenons in all reality.

My personal preference is hot hide glue on chair parts, but that's just me and YMMV.

Mike

[Mike Henderson]

I do my tenons on the table saw. If I have to cut a complex tenon (one that angles one or two ways - especially for a chair), I use a commercial tenon jig on the table saw. The tenon jig only cuts the side cheeks so you have to trim the ends by hand (with a chisel).

If I made the mortise with round ends (router, slot mortiser, or even drilled out), I just round off the tenon with a chisel (usually) or a rasp (not as often).

I prefer regular tenons but I think loose tenons are plenty strong enough.

Mike

[Greg Hines, MD]

The advantage of the loose tenon is twofold. First, you cut your workpieces to final length, without having to add on the length of the tenons. Second, you can produce a long line of the tenon stock with a router table, and then cut them to length as you need them. Generally, you round over the corners of the tenons and then you don't have to do anything with the rounded ends of the mortises.

Doc

[Mike SoRelle]

The advantage of the loose tenon is twofold. First, you cut your workpieces to final length, without having to add on the length of the tenons. Second, you can produce a long line of the tenon stock with a router table, and then cut them to length as you need them. Generally, you round over the corners of the tenons and then you don't have to do anything with the rounded ends of the mortises.

Doc

Sometimes I just cut my tenons slightly narrower and leave the rounded parts open, since the edges would be long grain to short grain, they really aren't a good glue surface anyway.

Mike

[Travis Shopbell]

I have been making mine with the table saw including the compound tennons with some special jigs I build out of scrap wood and the mortise I ave a straight shank router bit set up in my drill press at high speed It isnt fast but that is how I built my first rocking chair well really my first wood project
http://i302.photobucket.com/albums/nn93/deeremanphoto/DSCN0455.jpg?t=1210372130

[Greg Hines, MD]

I have been making mine with the table saw including the compound tennons with some special jigs I build out of scrap wood and the mortise I ave a straight shank router bit set up in my drill press at high speed It isnt fast but that is how I built my first rocking chair well really my first wood project
http://i302.photobucket.com/albums/nn93/deeremanphoto/DSCN0455.jpg?t=1210372130


Nice chair, and welcome to the creek.

Doc

[Chris Padilla]

Allow me to get the holy war going! :D

I would think that loose tenons to be stronger than integral tenons and the reason is glue. Loose tenons will have twice as much glue as an integral tenon.

We've all seen joints with modern-day glue in stress tests that all seem to break at the wood rather than at the glue joint. Hence, glue is stronger than wood. Hence, I think loose/floating tenons to be stronger than integral/traditional tenons.

To bring in more fuel on this potential holy war, Jim Lindsays's Dowelmax stress tests showing how dowels are stronger than traditional M&T joints reiterates this point in my eyes. The dowels are glued on both sides, like a domino, but unlike a traditional M&T joint. So I believe that dowels or dominos or loose tenons are all stronger than traditional M&T due to the glue. I would love to see Jim do his stress test with a loose tenon....

[Steve Flavin001]

matched round tenons nd mortises. :D

[glenn bradley]

Make a normal tenon and round over the edges with a rasp.
That's what I do . . . or a chisel if they're smaller ones.

[Kevin Groenke]

Allow me to get the holy war going! :D

I would think that loose tenons to be stronger than integral tenons and the reason is glue. Loose tenons will have twice as much glue as an integral tenon.


I want to believe this but I'm having trouble getting there in some situations.

A particular instance in which I feel that dowels/loose tenons are inferior to a tenon machined on the end of a piece of stock is when a mortise (for a loose tenon) is machined in the end grain of a piece of stock with inadequate side wall dimensions (such as a chair stringer or rung). In such a situation I believe the strength of the joint will be compromised and the likelihood of the rung/splitter failing along the grain would be higher than it would be with solid stock.

I actually fit ind easier to cut tenons than mortises anyway. Through and wedged through tenons are pretty: through dowels.. not so much.

Michael Moore of Victoria, BC has designed a fantastic jig (think woodrat only simple) that uses a plunge router to mill straight, angled and compound angled tenons in ~15 secs. I've been meaning to make one but, of course, haven't gotten around to it.

-kg

[Jesse Cloud]

The advantage of the loose tenon is twofold. First, you cut your workpieces to final length, without having to add on the length of the tenons. Second, you can produce a long line of the tenon stock with a router table, and then cut them to length as you need them. Generally, you round over the corners of the tenons and then you don't have to do anything with the rounded ends of the mortises.

Doc

Another advantage is that there is no shoulder to the tenon, so you are almost guaranteed a good fit against the mating piece.

[Frank Drew]

There are some good reasons to use loose tenons in some situations but I don't think they're stronger than integral tenons. Think about it: We've all seen glue joint failures allowing a tenon to pull out of a mortise... tables, chairs, etc. This failure could theoretically happen to either end of a loose tenon joint (admittedly more easily to the cross grain end). But the likelihood of an integral tenon "pulling out" of the wood it's part of is practically nil, so for all but the rarest of circumstances that end of the joint won't ever fail in that manner.

The examples of glue joints being stronger than the surrounding wood are true, but aren't relevant to this question; any force that would break the wood before the glue line would apply equally to joints with loose or integral tenons.

[Andy Richards]

I saw a snipet online of Norm Abrahms show 2011 for an outside chair (not the whole show). For the rear legs, he used an mdf template with router openings to make the mortises.

How do you make the tenons that have round sides? Or is he using loose tenons?


I saw the same show. He used a rasp to round the tenon edges.