# Tenon sizes



## ACV (Sep 19, 2006)

Doing up some mortise & tenons out of Oak for chairs...

I have a 3/4 inch rail and was going to do a 1/4 inch tenon but am wondering I should up the size to 3/8....my tenon length is about 1 inch and the depth I am questioning myself with also.

If anyone would please give me their 2 cents on width and depth I would greatly appreciate it.

Thank you,
Allison


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## bobj3 (Jan 17, 2006)

Hi Allison

I would suggest using 3/8" wide ones, because the bit you will need to do the job is a bit stronger and you can but the slot in with a pass or two unlike the 1/4" bit that will take up to 4 passes, 1/4" bit do like to break off in Oak...not to say anything about the heating up on the bit...

If you are going to use the floating type tenons you can make your own with the Band saw,table saw,and round them over on the router table with a bead bit...

I try and keep 2 to 3ft. long ones on hand so can just cut off what I need just like dowel rods in fact in the same 4" dia. PCV tube for storage..I cut them off 2" long the norm and the slot is 1 1/16" in ea.board, the ones I like best are 1 1/2 wide...but I also have 1" and 2" wide ones for some jobs...

So to say if you make your own make 5 or 6 ,3ft or 2ft long ones at the same time they do come in handy for many jobs... and once your set up to make them they are easy to make, you can buy them pre made but they are not cheap at the Rockler store...

Pls. post a picture or two once you get the tables and chairs done I would enjoy seeing them plus a snapshot of your new shop tools,by the way how do you like your new 8" jointer ?


Have a good day Allison, keep the heater going in the shop  Xmax just around the corner...you only have about 22 days to get this job done 
have fun...

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ACV said:


> Doing up some mortise & tenons out of Oak for chairs...
> 
> I have a 3/4 inch rail and was going to do a 1/4 inch tenon but am wondering I should up the size to 3/8....my tenon length is about 1 inch and the depth I am questioning myself with also.
> 
> ...


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## Mike (Nov 22, 2004)

Allison, you are correct; as a general rule we make our tenons 1/3 the thickness of the material. In this case I agree with BJ that you are better off making the tenon 3/8" thick. Your 1" tenon length sounds right to me. Chairs are subject to much more movement and stress than a table of the same size. I believe in building items like this as "bulletproof" as possible.


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## ACV (Sep 19, 2006)

So...Thinking last night and seeing Bj's and Mike's posts...I am going to go with the 3/8 by 1 inch tenon...Now I am concerned with the length as one area I only have 3/4 inch to slide into but in the legs I have 1 1/2 inches.

Any suggestions on a depth?

Allison


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## bobj3 (Jan 17, 2006)

Hi Allison

Go with 1/2 the width of the leg, that's to say if the stock is 1 1/2" thick put the slot in 3/4" deep ,this is true also if the stock is 3/4" thick put the slot in 3/8" deep ,you don't want to remove the strength of the leg by remove to much of the leg and then on the 3/4" wide stock you may want to use 1/4" tetons ,the 3/8" wide slot will take alot from the strength of the leg and then put the slot in 1/2" deep for 1/4" ones...no fast rule you just need to use your head and take a hard look at the joint,you want to make it strong by adding the joint.  not make it weaker  that's to say the parts of the joint must fit right and tight,make a test fit b/4 you glue it up, it should be tight b/4 the glue is in place all the glue will do is fill the space and if it's lose the joint will fail in a short time,many use a gross dowel pin to lock the joint in place ,they work well and are hard to see if you don't want then to show..but they do look great sometimes if you use like walnut (dark wood) so they stand out...it shows you took the extra time to make a great chair that will stand up for a long time..1/8" and 1/4" dowell pins you can buy from the craft store or your woodworking supply outlet..




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## Mike (Nov 22, 2004)

Good point BJ. Cross doweling or "pinning" the joint locks the tenon in place, just another way to add security against joint failure. I used this method on the porch swing I built. The seat supports had half lap joints where the bottom and back supports joined together. By installing 3 cross dowels I greatly enhanced the shear resistance of those joints. The reason I brought this up is to illustrate that dowels that pin a mortise and tenon together can be small since they are only reacting to pull apart pressure as opposed to a half lap joint where the dowels are providing additional support to the joint.
Another possible method of increasing the strength of the mortise and tenon joint would be to drill a hole through the leg, install a countersunk screw into the tenon and then plug the hole with a dowel. Depending on the look you are going for you might use both methods with contrasting dowels and plugs.
Lots of possibilities, let us know what you decide on.


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## ACV (Sep 19, 2006)

Hi Mike,

I found a video on finewoodworking.com. Thank you to both you and BJ for the idea...my mind is racing with ideas now.

I do have a mortise bit and am wondering what kind of lubricant I can use...I am going to post this question in Tools & Woodworking.

Allison


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## bobj3 (Jan 17, 2006)

Hi Allison

"what kind of lubricant "
I sometime use wax,,,I take a candle or bar of paraffine and rub it on the router bit, putts a nice shine on the wood...but only if the stock is not going to get a finish...or stain....or any glue...then I use Johnson floor wax on the project..

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## Falegname (Nov 26, 2007)

These may may be pretty basic questions, but this is my first attempt at using mortise and tenon. I've looked in a lot of places and the recommended thickness of a tenon is 1/3 the thickness of the stock, but I haven't found anything about how long to make a tenon.

I'm making a headboard and footboard by gluing up two 7/8" x 3" boards to make each post. The rails(stretchers? not sure of the correct terminology) will be 7/8" stock joined to the posts with mortise/tenon into the 1 3/4" edge. Would a 5/8" x 1" tenon with a 1/8" shoulder be a good size?

The rails between the headboard and footboard are 5/4 x 5 1/2 x 76. I plan to use 6" bed bolts with the addition of a mortise/tenon. What would be the recommended size for the mortise and tenon?

Is there a general guideline for the length of a tenon? 

Thanks for the help


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## Hamlin (Dec 25, 2005)

Hi James,

The length can be any size you which to make. You may want to go with a 3/4" tenon. Bj and or others should pop in soon.


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## bobj3 (Jan 17, 2006)

Hi James

"Is there a general guideline for the length of a tenon?

Not that I know about,,,,I would say it depends on the load the tenon needs to carrier, the more the load the bigger the tenon.

Like your 5/4, I would suggest 3/4" thick by 1 1/2" long tenons, beds are hvy. or to say they must take on a big load, 500lbs. the norm if not more.
The sheer on wood is very high but only when it's loaded right and tight...like most fastners joints....

Like the wood barns of old, beam that was in the notch (teton pocket) with one drive in wedge pin ,it would locked the joint up tight for ever once in place.

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## jerrymayfield (Sep 25, 2004)

I make almost all my tenons 1-1/4" long. Thats how I learned long long ago.

Regards

Jerry


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