Threaded Inserts strong for entry table legs?

[Patrick Irish]

I have a 50" x 7" x 1.5" live slab of some kind of wood, not really sure. It planed nice and I plan to make a narrow entry or sofa table. I want to use 30" hairpin legs BUT then got the bug to spice things up and use gold legs for the front and flush tapered oak legs for the rear.

The legs would be 30" tall and maybe 1"x2". Haven't decided but think I want to taper them to it end sup 1"x1".

Would using a single 1/4" threaded insert be alright? I'm more concerned with the side to side.

something like this but no apron and the front legs would be the hairpin OR I may just make it wood legs all around. I feel if I go 4 wood legs I'll have to do more than just threaded inserts for stability

[Jim Becker]

Interesting design challenge...my biggest concern is racking, but you might be able to tackle that with metal angle that's embedded flush in the bottom of the slab and welded to the metal legs with a way of interlocking with the wood legs at the back. Or the first part with the back of the slab fastened to the wall by a hidden means so there are only two front legs...like a shelf with legs. My personal choice would be just as in the sample photo, however and I'd use short aprons and a more delicate leg arrangement. That base is very heavy to my eyes from a proportion standpoint. Proportion is everything, IMHO. I tried really hard to get close with that on this natural edge hall table I recently made. It's a deeper apron because of the material and a thinner top, but the legs are sized to look comfortable with the size of the table top. (~36" wide by ~11" deep) I think you are on the right track with your taper proposal.

[Sam Murdoch]

Typically a single point of connection is a pivot point - doomed to fail without some augment. Jim offers some good ideas.

Sam

[Tony Bilello]

Firstly, a single point contact is always at risk, I think you should reconsider an apron.
Secondly, and most importantly, a 30" high table with a depth of only 7" will be very unstable especially if set on a carpeted floor where the legs might not be 'solidly' set.

[Jim Becker]

Secondly, and most importantly, a 30" high table with a depth of only 7" will be very unstable especially if set on a carpeted floor where the legs might not be 'solidly' set.

That's a really important point, honestly. My suggestion to anchor the back to the wall might be the way to go because of this, making it a shelf with supports up front. Fastening the two front legs using the technique the OP asked about might work ok for that because the top can't rack. Of course, if someone kicks a leg hard...all bets are off!

[Jamie Buxton]

That's a really important point, honestly. My suggestion to anchor the back to the wall might be the way to go because of this, making it a shelf with supports up front. Fastening the two front legs using the technique the OP asked about might work ok for that because the top can't rack. Of course, if someone kicks a leg hard...all bets are off!

If you fasten the rear of that table to the wall, you can get by with just one leg, in the middle of the front. I’ve done that.

[Derek Cohen]

I have a 50" x 7" x 1.5" live slab of some kind of wood, not really sure. It planed nice and I plan to make a narrow entry or sofa table. I want to use 30" hairpin legs BUT then got the bug to spice things up and use gold legs for the front and flush tapered oak legs for the rear.

The legs would be 30" tall and maybe 1"x2". Haven't decided but think I want to taper them to it end sup 1"x1".

Would using a single 1/4" threaded insert be alright? I'm more concerned with the side to side.

something like this but no apron and the front legs would be the hairpin OR I may just make it wood legs all around. I feel if I go 4 wood legs I'll have to do more than just threaded inserts for stability ...

Patrick, 7" is too shallow for legs to maintain stability, especially for a 30" tall table. The only way this could be done (freestanding) is to splay the legs to the outsides, say at 10 degrees.

Building a table with splayed legs is quite easy - the splay comes from the apron. Yell out if you want to go down this path and want some input.

Regards from Perth

Derek

[Mike Henderson]

Yeah, if you're only going to go 7 inches, I'd attach it to the wall and not use any legs. Like a fireplace mantle.

Mike

[Rick Potter]

My first thought was like Mike's. 7" wide slab? Where would that make the C/L of the legs? Someone will bump it and a child might be the one it falls on. Ouch.

Who vacuums the floor? That would be a likely way legs could get bumped pretty hard.

Sorry to be Debbie Downer.

[Malcolm McLeod]

I'll leave the design and construction techniques with what others have posted, but offer just a quick look at the structural loads. First some assumptions:
1. 30"T legs
2. tapered from 2x2 at the top, to 1x1 at the bottom
3. legs attached to the top with a 1/4" threaded insert centered in the leg. (For these purposes, it doesn't matter where on the top the leg attaches.)
4. no apron.

Bumping the leg (just a lever!) horizontally at the bottom with a 2 lb force results in a 30:1 'advantage' at the screw. The bump has a 30" lever arm; the top edge of the leg becomes the fulcrum, with a 1" lever arm from the thread. So, 60 lbs trying to pull the screw or insert. I don't think threaded inserts are going to shine at this tensile load resistance - they're much better resisting shear (side loads).

And 2lbs is not much. Think about kicking a 2 lb dumbbell, or hitting it with a vacuum (neither is perfect analogy, but you get the idea). Even if it isn't wrecked the first time, my suspicion is that with 8-10 toe taps, your going to have build a beautiful piece of firewood.

I'm with the crowd here. Its why we have aprons. Even a very short one converts the load at the leg/top interface to shear - - in the above case, the fulcrum moves to the bottom edge of the apron where it meets the leg. The long lever arm is shorter, the short lever arm is longer, and most important (to me at least) is that the direction of the load at the top changes by 90*.

[Ted Reischl]

7 inches wide is a shelf, not a table. Besides, it is going to look goofy as all get out. The proportions of that are not pleasing to the eye. There are some things you really should not do just because you can.