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Help constructing a joint

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Forum topic by damnHippie posted 897 days ago 1276 views 0 times favorited 17 replies Add to Favorites Watch
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damnHippie

35 posts in 2371 days


897 days ago

Topic tags/keywords: question

I need help executing a joint. I have a 1.5” x 1.5” x 16” leg, and want to join a 3/4” x 1.5” x 20” cross beam to the leg at a 45 degree angle. Hopefully this image helps explain…

I would like to use mortise and loose tenon joinery. So, the question is, do I chisel a flat into the corner of the leg, or do I saw/chisel a bird’s mouth into the cross beam?

Or do I go crazy and treat the entire beam like a tenon and put a 3/4” x 1.5” mortise in the leg?

-- 10 fingers, 2 eyes, and healthy lungs. for now. :P


17 replies so far

View CharlieM1958's profile

CharlieM1958

15639 posts in 2814 days


#1 posted 897 days ago

Do you have a table saw? I would make a jig to hold the leg at a 45 degree angle to the blade, and then remove the correct amount of material by making multiple passes, similar to the way you would cut a box joint.

(P.S. A guy who calls himself damnHippie needs help making a joint???) :-)

-- Charlie M. "Woodworking - patience = firewood"

View DS's profile

DS

2131 posts in 1016 days


#2 posted 897 days ago

hahaha @ Charlie…

A guy who calls himself damnHippie needs help making a joint???

It must be Monday—My first thought was, “Are hippies stereotypically good woodworkers?”
Then I got it… Joint. Like what the guys at the back of the school bus had…
That made me laugh twice as hard.

r.e. the OP question… I would cut the birdsmouth joint and add some big fat dowells and a corner bracket just for good measure. There’s a thousand ways to skin this cat, including commercially available brackets.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View oicurn2it2's profile

oicurn2it2

121 posts in 2434 days


#3 posted 897 days ago

that my friend is quite the joint , I’m curious how much are you prone to traditional joinery ?,
the Japanese would cut the birds mouth leaving a tenon in the middle and birds mouth (acting as the shoulders)
if cut correctly would mate to the leg creating the crisp lines and the most structurally sound joint ,

cutting the the recess in the leg could cause some strength issues depending on how close to the top of the leg you went ,possibly snapping the corner off {above the skirt} along the grain (mind you I’m thinking in extremes).....

but if all that is met with a extra large “PFFFT” then by all means i agree with the brackets…

looks like a cool joint though …......

-- "when you think youre going to slow, slow down just a little bit more" .... Pop's

View canadianchips's profile

canadianchips

1831 posts in 1593 days


#4 posted 897 days ago

Cut a birdsmouth on the cross brace.Use a dowel to hold up-down support, the birdsmouth will provide sideways support. Cutting mortise into the “Leg” or chiselling flat will weaken the leg.

-- "My mission in life - make everyone smile !"

View Dave's profile

Dave

11137 posts in 1436 days


#5 posted 897 days ago

DS that wuz sum funny stuff right there.

-- Superdav "No matter where you go - there you are." http://chiselandforge.com

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damnHippie

35 posts in 2371 days


#6 posted 897 days ago

Thanks for the suggestions!

I should have been more detailed – the cross beam will support the majority of the piece—similar to this (and before anybody gets excited, that isn’t my work—it’s just something I found on the web to demonstrate the general idea):

Except, there are only two cross beams diagonally connecting the legs (rather than the 4 rails in the image above).

So, given that, does the mortise in the legs still compromise the strength of the piece?

-- 10 fingers, 2 eyes, and healthy lungs. for now. :P

View Dave's profile

Dave

11137 posts in 1436 days


#7 posted 897 days ago

I agree with Chips. Or you are going to have to find some crazy Japanese joint.

-- Superdav "No matter where you go - there you are." http://chiselandforge.com

View Sawdust4Blood's profile

Sawdust4Blood

340 posts in 1617 days


#8 posted 897 days ago

I have a jig that I use to cut splines in miter joints for boxes and frames. I would probably use that to cut a flat in the vertical leg and then mortise into the flat.

-- Greg, Severn MD

View a1Jim's profile

a1Jim

111999 posts in 2173 days


#9 posted 897 days ago

I think I would router a loose tenon mortise in the end of the cross member,then I would cut the 90 degree in the middle of the cross member using a shop made tenoning jig ,If the mortise was cut deep enough then all you have to do is cut another mortise in the corner of the leg using a jig that set on the corner with a flat spot to rest you router and ad a loose tenon ,after that some glue might be a good idea too. :))

-- http://artisticwoodstudio.com Custom furniture

View DS's profile

DS

2131 posts in 1016 days


#10 posted 896 days ago

The rail is actually going to be providing shear strength (not allowing it to collapse sideways). All the main load bearing will be done by the legs. The double rail has nearly the same effect as a single wide rail.

In the end, it’s going to come down to the joinery tools you have and what ideas you can wrap your brain around. My preference is dowells, because I have a pretty good setup for dowells. M & T—not so much, especially at those angles.
Your mileage may vary.

-- "Hard work is not defined by the difficulty of the task as much as a person's desire to perform it.", DS251

View CharlieM1958's profile

CharlieM1958

15639 posts in 2814 days


#11 posted 896 days ago

I would also add that the amount of weight to be supported is a factor to take into consideration.

Several people have mentioned how leg strength might be affected by one technique or another, but this may not be that big of a deal unless you are making an aquarium stand, or a step stool for your 400 lb. mother-in-law. :-)

-- Charlie M. "Woodworking - patience = firewood"

View Roger Clark aka Rex's profile

Roger Clark aka Rex

6940 posts in 2031 days


#12 posted 896 days ago

Jeez …... as a Damn Hippie, you must have dementia if you can’t remember how to construct a joint. :-)

-- Roger-R, Republic of Texas. "Always look on the Bright Side of Life" - An eyeball to eyeball confrontation with a blind person is as complete waste of Time.

View devann's profile

devann

1735 posts in 1288 days


#13 posted 896 days ago

you know something Roger. I wanted to see if he was rolling a joint.

damnHippie, I’d cut a tenon on the end of the 2×4. Cut a notch in the 4×4, and then cut a mortise for the tenon in the notch.

-- Darrell, making more sawdust than I know what to do with

View pintodeluxe's profile

pintodeluxe

3260 posts in 1409 days


#14 posted 896 days ago

Cut a shallow dado in the leg at a 45 degree angle. Cut a traditional tenon on the cross member, and finish with a mortise in the leg (loose tenon would work just as well.
Sometimes a similar effect is achieved by building square joinery, but orienting the entire base at a 45 degree angle. The woodworking is much more straightforward that way.
Michael Pichovich has a great article on fine woodworking website entitled “Hayrake Table.” It details techniques for angled, complex joinery.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View BTimmons's profile

BTimmons

2076 posts in 1081 days


#15 posted 896 days ago

Maybe you could do it kind of like this. Cut a through mortise connecting two opposite corners, then wedge it in place. Pardon the crude MS Paint rendering.

Looking at my illustration and the original image in this thread, I now realize that the mortise/tenon should be more tall than flat. But you get the idea. Perhaps the wedges could run horizontal rather than vertical.

I might be way over thinking this. I’ve never even cut dovetails by hand yet. But I think this would be a pretty creative way to approach this joint.

-- Brian Timmons, Big T Woodworks - https://www.etsy.com/shop/BigTWW - http://vimeo.com/98821147

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