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How to secure through mortise

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Forum topic by pete79 posted 03-22-2011 06:33 PM 2070 views 0 times favorited 11 replies Add to Favorites Watch
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pete79

154 posts in 2608 days


03-22-2011 06:33 PM

I’m working on building the bench in the image below. I’m now working on the stretchers that have a through mortise joint to attach them to the legs. I wasn’t planning on making a tenon on the stretcher, and I’m curious if simply making sure the joint is snug will be strong enough, or if I should consider pinning it with a contrasting dowel or even using some other method. I’ve never used a through mortise joint before, so any guidance would be great.

-- Life is a one lap race.


11 replies so far

View fussy's profile

fussy

980 posts in 2518 days


#1 posted 03-22-2011 11:50 PM

Pete,

You can pin it, but unless you’re careful you’ll end up splitting the tenon. What I would do is start the tenon in the mortise then apply glue to the rest of the tenon. This way the glue will be distributed throughout the mortise without the exposed end of the being messed up with glue. You definately need to secure the joints.

Steve

-- Steve in KY. 44 years so far with my lovely bride. Think I'll keep her.

View chrisstef's profile

chrisstef

15677 posts in 2473 days


#2 posted 03-23-2011 12:18 AM

If you want to get fancy you could wedge the tenon, i think i saw that done before. Id imagine that you could cut out a slot in the end of the tenon (the side that will be exposed) and using a wedge insert it into the slot expanding the tenon against the mortise. I think id slap some glue in there as well. I’ve got absolutely no experience doing this and i may even be talking out of my a** but that was the first thing i tought of.

BTW i like the design.

-- rock, chalk, jayhawk

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TheDane

4997 posts in 3130 days


#3 posted 03-23-2011 12:39 AM

On through tenons, apply glue to the tenon, leaving the end that will be exposed dry … don’t apply glue to the mortise.

I would suggest draw-boring … you drill a hole through the side of the mortise, insert the tenon, mark the center of the hole on the tenon cheek, then remove the tenon and drill a hole approx 1/32” closer to the shoulder of the tenon. Chamfer the end of the pin … when you drive it through, it will draw the joint tight.

—Gerry

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View stefang's profile

stefang

15512 posts in 2801 days


#4 posted 03-23-2011 01:10 AM

I second the Dane’s suggestion, but your bench will be a whole lot stronger/rigid with a shouldered tenon. I’m sure you know that, but I couldn’t keep from saying it.

-- Mike, an American living in Norway.

View Lee Barker's profile

Lee Barker

2170 posts in 2317 days


#5 posted 03-23-2011 01:24 AM

I’m not sure exactly what you’re asking, Pete.

As I reread it I am thinking you’re asking about the center stretcher which travels between the end stretchers and you’re wondering what that joint ought to be.

I also gather you’re more concerned about strength than design.

If I’m correct so far, then you’re asking about that butt joint. It’s not a glue joint, of course, so you need something in there to get some flat grain to flat grain. That could be dowels from outside the stretcher or even biscuits.

But since the tenons show through the legs, I would think this one should show as well. And it would be strong enough so that you could put a shelf down there and display your priceless collection of anvils! : )

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

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stefang

15512 posts in 2801 days


#6 posted 03-23-2011 03:35 PM

I just had to tell you Lee that your quote from Shakespeare could have been written about me, lol.

-- Mike, an American living in Norway.

View Lee Barker's profile

Lee Barker

2170 posts in 2317 days


#7 posted 03-23-2011 03:51 PM

Steal it! I did!

I saw the play with a busload of sixth graders in Ashland, Oregon at the Shakespearean Festival there years ago. The line jumped off the stage and into my head like it was amplified at a rock concert. Next day at home I looked it up to get it right.

Thanks for the comment Mike.

Kindly,

Lee

-- "...in his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View richgreer's profile

richgreer

4541 posts in 2541 days


#8 posted 03-23-2011 04:05 PM

If you have a snug fitting mortise and tenon, glue is all you need. Anything else is more for looks than function.

-- Rich, Cedar Rapids, IA - I'm a woodworker. I don't create beauty, I reveal it.

View therookie's profile

therookie

887 posts in 2294 days


#9 posted 03-23-2011 04:09 PM

in my personal opinion just wedge it. I cant remember the exact issue but American Woodworker had an issue out that covered wedge mortise and tennon joints.

-- http://aewoodworks.webs.com

View NathanAllen's profile

NathanAllen

376 posts in 2611 days


#10 posted 03-23-2011 09:31 PM

Another vote for wedge. If you make the tenon too tight it can be a bear to fit the final piece. By undercutting a small amount to allow for the tenon to expand you make a very tight joint. Cosmetically a tusk will also cover up the smallest amount of slop in the size of the tenon or mortise, through cuts aren’t very forgiving.

To prevent splitting the trick is to bisect the tenon then use a drill at the base of the cut to allow for the two tusks. Assemble the piece then glue up the tip of the wedge and drive it home.

Screws and plug or Drawbore work great with non-through M&T but the tusk covers up any sizing, has a good cosmetic look and depending on how decorative you want to be you can still apply a plug to provide a visual on both sides of the leg. Whether you put a drawbore or screw under that plug is your choice.

View Glen Peterson's profile

Glen Peterson

556 posts in 2523 days


#11 posted 03-23-2011 11:25 PM

I vote for wedges in a contrasting color. Folks above are right, glue is enough, but the wedges look great.

-- Glen

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