Is 10 Degrees Too Extreme?

[onocoffee]

This may have to be filed under "listening to too many sources".

Recently, I was listening to a podcast (maybe WoodTalk) where the hosts were talking about chair legs and their angles. Evidently, legs set to 10 degrees is "too extreme" and is prone to failure.

I'm asking because I've made a few three-legged chairs that I set the front two legs at 10 degree angles. Is this angle too extreme?

I find that I like the aesthetic of the legs at this angle and I find that this angle also gives the chair solid stability. That said, I can change the angle if it will truly be prone to issues in the future. While each one varies, the front legs are all right around 27mm in thickness (maybe 25mm, at the minimum).

I'm interested to know what you think. And if there is a better/ideal angle for such legs. Thanks!

 

[luvmytoolz]

I have to agree somewhat, it looks to me that as a shifts their weight on it, there might be considerable sideways as well as front facing forces simultaneously that may present an issue.

I'd just suggest sit on them and wriggle around to ascertain the degree of flex felt when the load shifts. You'll know pretty quickly if they feel like something might give.

When in doubt, it helps me to picture how my kids might abuse and mis-treat use them.

 

[bobtskutter]

They look great!
I have no scientific basis for the next comment...
...It looks as though the weak point is the mortice and tenon (?) joint at the top of the leg where it's attached to the underside of the seat. I can imagine a situation where the front legs splay out forwards and sideways if too much downwards force is put on the seat.

Would using a through tenon with a wedge create a stronger joint?
Do you cut the tenon out of the leg material, or is it a domino joint?

Regards
Bob

 

[onocoffee]

They look great!
I have no scientific basis for the next comment...
...It looks as though the weak point is the mortice and tenon (?) joint at the top of the leg where it's attached to the underside of the seat. I can imagine a situation where the front legs splay out forwards and sideways if too much downwards force is put on the seat.

Would using a through tenon with a wedge create a stronger joint?
Do you cut the tenon out of the leg material, or is it a domino joint?

Regards
Bob

I use 10mm Dominos (two) to attach the legs to the seat. Cutting leg tenons is Master-level stuff!

 

[derekcohen]

A few of my builds.

These stools have legs at 10 degrees ...



The legs of these chairs are at 14 degrees ...






Regards from Perth

Derek

 

[luvmytoolz]

With the angle combined with using loose tenons to join the legs to the seat, I think I'd be a little more concerned about the legs buckling under a shifting load now.

I wouldn't necessarily worry about modifying them, for general use and most people I'm sure they'd be absolutely fine, but a stout person pushing off the front to stand up might be a problem.

 

[luvmytoolz]

@derekcohen Your chairs Derek I don't think are really comparable as the legs on all have 2 anchor points which help counter the forces, and the stools also have the legs going right through the seat, which adds tremendous support.

 

[ChuckS]

This may have to be filed under "listening to too many sources".

Recently, I was listening to a podcast (maybe WoodTalk) where the hosts were talking about chair legs and their angles. Evidently, legs set to 10 degrees is "too extreme" and is prone to failure.

I'm asking because I've made a few three-legged chairs that I set the front two legs at 10 degree angles. Is this angle too extreme?

I find that I like the aesthetic of the legs at this angle and I find that this angle also gives the chair solid stability. That said, I can change the angle if it will truly be prone to issues in the future. While each one varies, the front legs are all right around 27mm in thickness (maybe 25mm, at the minimum).

I'm interested to know what you think. And if there is a better/ideal angle for such legs. Thanks!

Maybe it's the angle that you took the photo, the front legs look too slanted to me from an aesthetic point of view.

That said, the sturdy legs seem fine and should stand normal use.

Fwiw, the Tage Frid three-leg stools I have made have the front legs at 6*. https://modernegallery.com/works/furniture/seating/other-seating/tage-frid-three-legged-stool-1983/

 

[Steve1]

Evidently, legs set to 10 degrees is "too extreme" and is prone to failure.

I don't think I would agree with that.
In any situation, one should be designing/building for the anticipated loads. If the loads are higher, the required strength of the joinery needs to be that much higher.
Yes, a chair leg at a 10 degree angle will have 18% of the vertical load transferred horizontally, and with a pretty long torque arm, which sure don't help.
So one would have to build one's chair that takes account for this this -- as was done in derekcohen's stools in Post #5.

However, if the statement were worded a bit differently, I might agree with him.
For example, if he stated that 5 degree leg angle were a better choice because it results in a stronger connection.

 

[luvmytoolz]

Fwiw, the Tage Frid three-leg stools I have made have the front legs at 6*. https://modernegallery.com/works/furniture/seating/other-seating/tage-frid-three-legged-stool-1983/

I've just gotta say, what a sensational design! Really beautiful!