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Need suggestions for fixing a joint

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Forum topic by ATLJack posted 816 days ago 640 views 0 times favorited 6 replies Add to Favorites Watch
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ATLJack

27 posts in 918 days


816 days ago

I am in the process of building two twin beds for my boys out of white oak. I am attempting to copy this bed that my wife saw at Pottery Barn Kids:

This is my progress thus far:

Unfortunately, however, I made a significant error and need your suggestions on a fix. The top and bottom rail of the headboard are jointed to the posts with a mortise & tenon joint. But I screwed up the width of the top and bottom rails and dont have enough width for the tenon to be as long as it should be. The rails are 7/8” thick, the tenon is 3/8” thick, but because the rail isnt wide enough the tenon is only 1/2” long.

Any suggestions on what I can do to strengthen the joint without remaking the top and bottom rails? Since I am making 2 beds there are 8 rails with lots of mortises and I dont want to do them over.

My plan was to add to the arts & craft style by making a fake through tenon by adding a block on the outside of the post to give the illusion of a through tenon. I am thinking that now I could use this block to hide screws that I drive through the post into the rails for some added strength.

Thoughts?


6 replies so far

View PurpLev's profile

PurpLev

8476 posts in 2282 days


#1 posted 816 days ago

you can elongate the tenon, but maybe an easier and more robust solution (considering it’s for a bed) is to cut the tenons completely off and replace them with mortises – and use floating tenons all together. this way you can choose how long the tenons will be… can make them through or non through tenons as well.

at least thats probably would I would do.

-- ㊍ When in doubt - There is no doubt - Go the safer route.

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jaidee

42 posts in 1413 days


#2 posted 816 days ago

On the lower rails (which bear the brunt of stress) I have used a 2 piece angle bracket that has a tightening screw. I’ve used it to strengthen an older bed that I restored and it works great. I’ll try to remember where I purchased it. Another option is to use a bed bolt (Rockler.com?) which could be hidden by the false tenons and would be much stronger I think than just screws.

jd

-- I used to be all thumbs......'til I got a tablesaw!

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ATLJack

27 posts in 918 days


#3 posted 816 days ago

Thanks. I am glad I asked the question but honestly am a little embarrassed that I didnt think of floating tenons. Since I already cut mortises in the two posts shown above I might elongate those with floating tenons, but change the others to pure floating tenons.

View crank49's profile

crank49

3378 posts in 1604 days


#4 posted 816 days ago

I would be most concerned about the attachment of the side rails. That is where almost all the stress is in a bed frame.
As for the head board rails, since the tennons are only 3/8” thick, 1/2” length is not all that bad proportionally. Could you not maybe shave the shoulders down another 1/8” and have 5/8” long tennons. You could probably move the side rails out by 1/8” to compensate.

How do you plan to attach the side rails? Will the cross rails you are wanting to lengthen be in the way of the side rail attachment?

-- Michael :-{| “If you tell a big enough lie and tell it frequently enough, it will be believed.” ― A H

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ATLJack

27 posts in 918 days


#5 posted 816 days ago

For the side rails I was going to cheat and use something like this:

I could cut the shoulder back another 1/8 of an inch, but is a 5/8” tenon really going to be long enough?

I didnt think of this either, but your suggestion got me thinking that my posts are 3” square so if I want to I could push the side rail out to the outside edge of the post and gain about an 1” as apposed to installing the side rail in the middle of the posts. Doing the math in my head and without looking at the plans, I think I could cut the shoulder back another inch but I would loose the symmetry of the headboard and it might look odd not having the side rails in the middle of the posts. My tenon would therefore be 1 1/2” long which should be sufficient.

Honestly, even considering the aesthetic concerns I mentioned, I may prefer to do that over the alternative of making 16 floating mortise and tenons joints. My wife gave me a deadline that is fast approaching.

Thoughts?

View Lee Barker's profile

Lee Barker

2163 posts in 1484 days


#6 posted 816 days ago

I like the floating tenon idea, and it’s not as challenging as you might think. Your tenons already give you the layout. It’s just a matter of building a fixture that clamps on the end and contains your router’s travel.

As an alternative, have you considered pinning the 5/8 tenons? This could be done on the inside of the bed, and I would expect the oak to hold the pins well. The pins could be quarter inch dowels, or 3/16 metal.

I think your concerns about the strength of that joint are overstated. The only way that joint could loosen is by the whole thing racking, and with all those slats in there, that’s simply not going to happen. There is no force in the life of the bed that will pull those two legs apart.

Notice that no one responded to the screw idea. That’s going into end grain and is not worth the effort.

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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