Mortise and Tennon

[Gary Sutherland]

As a fairly new woodworker, I would like your opinions about traditional and loose tennons. I've never seen this discussed specifically, 'tho I may have missed something.

I see David Marks using his multi-router quite often to make loose tennons, and it seems quicker and easier than traditional M/T (I know quicker is not always the answer).

Except for through tennons, when would you NOT use loose tennons? I'm interested in either practical of philosophical reasons.

Also, what do you think of the Multirouter? (Unfortunately, it's not in my immediate future$$). How would the Multirouter (very pricey) compare in usefulness to a horizontal mortiser like the Rojek or Laguna (only fairly pricey).

I'm not trying to establish that one method is always preferable to the other, just curious about your experiences and views.

I saw David Marks at a WW show, and was going to ask him his opinion, but there were so many people waiting to speak to him that I wasn't able to.

Thanks for your comments....

Gary

[Alan Tolchinsky]

Hi Gary, I started using loose tenons and I can't off the top of lmy head think of where you could not use them. I make my mortises with a router and jig and it's been very easy to use. Then I size up the tenons with a planer for the width and cut to length. So far so good. Maybe we could discuss the advantages and disadvantages of them. Alan in Md.

[Jim Becker]

There is no strength difference and loose tenons are "easier" to work with--no figuring stock to be longer to accomodate a tenon; just "butt" joints in effect. Aside from the through tenon situation you already identified, I don't think I'd use loose tenons for angled tenon situations where milling the mortise in one or both pieces might be more difficult. But that's me...

[Mark Singer]

There have been previous posts on this. Here are some links:

http://www.sawmillcreek.org/showthread.php?t=5753&highlight=loose+tenons

http://www.sawmillcreek.org/showthread.php?t=5741&highlight=loose+tenon

I have used the "loose" method on chairs and it has worked well for angled joints. The key for angled tenons is always proper layout whether loose or traditioal.

[Mike Cutler]

Gary. A well done loose tenon is a very strong joint. It has all the requirements that are necessary for M&T joinery. If it fits tight and and is properly sized and located, it will work. The only application That I believe it is not suited for, is a haunched tenon. This is the M&T joint at the top of some table legs or posts that has to support a lot of shear load. But in all fairness a traditional M&T is not strong enough either in this application. I'm a traditional M&T guy, I learned to size and cut them 30 years ago, so it's just what I do. It's not right or wrong just what I'm comfortable with.
One nice thing about loose tenons is that the joint can be made very quickly with a router and 2 bits. If you had to do a lot of joints this would save alot of time.
I've looked at the "Bead-Lock" system, but there appear to be too many variables for me.
If you go with loose tenons my only advice is to make sure that the tenon is the same material as the mortise pieces, this way the glue joint is predictable. My .02 fwiw

[Mike Cutler]

Mark. The tenon stock in the photo seems to have a series of grooves running the length of the stock. What was your intended pupose for these grooves? Nice sofa by the way

[Jim Becker]

Mark. The tenon stock in the photo seems to have a series of grooves running the length of the stock. What was your intended pupose for these grooves?
I'm not Mark and don't play him on TV, but the grooves give any excess glue a place to go and relieve any "suction" while fitting the joints.

[Mark Singer]

Jim is correct! .....Again! Like dowels the surface texture be rough...bandsawed teture is good and the scoring increses the strength by allowing even coating of glue and the ability to"pump" the excess out when the tenon is tapped into the mortise. Glue should be placed on the head of the tenon and its sides to insure it will push the glue into the mortise.

[Mac McAtee]

See this thread:

http://www.sawmillcreek.org/showthread.php?t=7469

[Mark Singer]

It seems obvious, but a friend of mine made this miastake....the grain should run parallel to the mortise stock for strength....10x difference!

[David Rose]

Yup! The first tenons and mortises that I cut with a Leigh FMT were a "suction fit". Just a little excess glue, even allowing for extra depth in the mortises, clamping rails and stiles blew out a side wall on every stile! And it didn't take a lot of pressure to do it. Hydraulics are powerful. :D It was correctable to reasonable standards fortunately. With a sanded in wiping varnish finish they were well hidden, but I won't make that mistake again... I hope. :o

David


I'm not Mark and don't play him on TV, but the grooves give any excess glue a place to go and relieve any "suction" while fitting the joints.

[Kirk (KC) Constable]

Hmmmm...as often happens, I'll be the lone voice of dissention. :-)

While a loose tenon may be just as strong, or in some cases even stronger than a traditional tenon, it seems like cheating to me. Since I started doing this for money, I tend to look at things from a 'buyer's' perspective...and if I were buying a piece of custom furniture, I'd expect 'traditional' joinery. So I don't do loose tenons 'on principle'.

Unless you're set up with a multi-router (or similar gizmo), I'd also question how much 'easier' it is than the traditional joint. I think that all depends on what you're used to doing...kinda like hand-cut vs machine-cut dovetails. Lotsa oldtimers say they can cut a box of dovetails by hand faster than you can with a jig...and experience has everything to do with that. Cutting a properly fitting tenon can be frustrating at first, also. I'll go out on a limb and say if we throw cutting the leg mortises out of the equation, I can cut the tenons on four pieces of a table apron and put it together faster than you can using loose tenons.

KC

[Mike Cutler]

Kirk. I think I need to clarify a point. When I stated that the joints were faster and easier with a router, I was approaching it from the perspective of Gary being new to woodworking and not having alot of machines, fixture and jigs in place already to make the joint. With the router, a lot of tenon stock can be made upfront and cut to length easily once the mortises have been done. But you are correct, the joint can be made very quickly using other techniques.
I perfer to make the M&T joint in the traditional manner, I don't use the neander methods, tho' I'm completly capable of them. I just don't have the time. But sometimes it is fun to get the marking knife and chisels out and have some fun, theraputic also.
I've never used the spline groove technique that Mark detailed, I'll have to try it someday. I've always left space at the bottom of the mortise and painted the shoulders and cheeks of the tenon as well as the inside of the mortise with glue prior to assembling the joint. With respect to Mark, it seems that most of his work is custom, one off type pieces that require solutions a little outside the realm of the traditional.
David. I had looked at the FMT, and was wondering just how tight a fit it made. It would appear from your post that it is very tight.
To add to the initial question of this post. What are peoples opinion of square vs. rounded shoulders on tenons? I've read that the rounded shoulder is supposed to place more uniform stress on the mortise member than a traditional four square tenon due to the radius of the shoulders distributing the force more evenly.

[Mark Singer]

I agree with Kirk in principle....it is important to learn to make motise and tenon joints both ways. In one of my links to a previous post I state that I oftem prefer to make the joint the traditional way and enjoy the precision of layout that is required. The recent "pool enclosure" thread had about 250 traditional M&T joints, that would have been impossible to do by the loose tenon method do to the small cross section of the slats.
http://www.sawmillcreek.org/showthread.php?t=11313&highlight=pool+enclosure
If you master both techniques and can do the with hand tools and machines then you have many options. The templates make repeating the joint easier in most cases. When you are making 250 traditional mortise and tenon joints, you need to devise a machining method that is precise and repeatable. There is nothing wrong with this and if fact creating the solution is the essence of fine woodworking. Without a shortcut and fast repeatability ,the joint , often is deleted and a nail gun approach to appling the slats is chosen. This makes for a lower quality joint and project. Loose tenon joints are sometimes the perfered method and will still make a joint that is strong. If a new woodworker is comfortable with one metod or the other its fine at the beggining...but eventually knowing both techniques are essential...it is the primary joint in furniture construction

[David Rose]

Mike,

I should have said more about the FMT probably. As I got the machine, the joints were looser than I wanted. They are very easy to adjust with this rig. Easy to within .002 with a single screw to turn that has calibration marks. I liked the way they felt with a nice suction fit. The radiused ends of the tenons are left a little short for a slight movement adjustment and to allow for some glue squeeze out. I had minimized that too. There was just no place for the excess glue to go! But it was all my fault and part of my education with mortises and tenons.

David