I don't really intend to build this; not exactly anyway, and maybe not
at all. But I do intend to build a bench at some point, and I like the
idea of slats with space in-between them. For now I'd just like to gauge
if something like this would be strong enough. Let's suppose a
worst-case of three people sitting on it.

https://www.flickr.com/photos/gdguar...57639547178715

[Scroll right for other views]

And how would you go about figuring it out?

Here's my thought process so far. I figure 11 1x3s in this orientation
should hold a good bit of weight, but even if it's enough, two problems
remain.

1. They could twist.

That could be cured by putting some short pieces of the same material
between the long slats; in the middle, as I've shown them, or perhaps
two sets each 1/3 of the way from the end.

2. The joints where the top slats meet the "legs" have too little
surface area. The "racking" forces might cause the joints to fail.

To counteract that, I made two of the "slats" out of 1x8 instead,
producing better geometry against racking.

I'm already thinking of moving the legs closer to the center, and of
designs that look nothing like this one. But I'm still curious to get
your opinions to calibrate my own sense of the sturdiness of something
like this.

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On 1/17/2015 10:12 PM, Greg Guarino wrote:
I don't really intend to build this; not exactly anyway, and maybe not
at all. But I do intend to build a bench at some point, and I like the
idea of slats with space in-between them. For now I'd just like to gauge
if something like this would be strong enough. Let's suppose a
worst-case of three people sitting on it.

https://www.flickr.com/photos/gdguar...57639547178715


[Scroll right for other views]

And how would you go about figuring it out?

Here's my thought process so far. I figure 11 1x3s in this orientation
should hold a good bit of weight, but even if it's enough, two problems
remain.

1. They could twist.

That could be cured by putting some short pieces of the same material
between the long slats; in the middle, as I've shown them, or perhaps
two sets each 1/3 of the way from the end.

2. The joints where the top slats meet the "legs" have too little
surface area. The "racking" forces might cause the joints to fail.

To counteract that, I made two of the "slats" out of 1x8 instead,
producing better geometry against racking.

Overall, it looks pretty strong to me. Only problem I see is that the
top is flat. If you sit for a while it will not be as comfortable as a
seat with a dish to it. The 1 x 3s will hold a lot of weight though.

Greg Guarino wrote:
I don't really intend to build this; not exactly anyway, and maybe not
at all. But I do intend to build a bench at some point, and I like the
idea of slats with space in-between them. For now I'd just like to gauge
if something like this would be strong enough. Let's suppose a
worst-case of three people sitting on it.

https://www.flickr.com/photos/gdguar...57639547178715

[Scroll right for other views]

And how would you go about figuring it out?

Here's my thought process so far. I figure 11 1x3s in this orientation
should hold a good bit of weight, but even if it's enough, two problems
remain.

1. They could twist.

That could be cured by putting some short pieces of the same material
between the long slats; in the middle, as I've shown them, or perhaps
two sets each 1/3 of the way from the end.

2. The joints where the top slats meet the "legs" have too little
surface area. The "racking" forces might cause the joints to fail.

To counteract that, I made two of the "slats" out of 1x8 instead,
producing better geometry against racking.

I'm already thinking of moving the legs closer to the center, and of
designs that look nothing like this one. But I'm still curious to get
your opinions to calibrate my own sense of the sturdiness of something
like this.

---
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Looks strong enough to me. Were you thinking about using it indoors?
For outdoors, that is a lot of end grain sitting on the ground.

--
 GW Ross 

 Please Tell Me if you Don't Get This 
 Message. 

"Greg Guarino" wrote:

I don't really intend to build this; not exactly anyway, and maybe
not at all. But I do intend to build a bench at some point, and I
like the idea of slats with space in-between them. For now I'd just
like to gauge if something like this would be strong enough. Let's
suppose a worst-case of three people sitting on it.

https://www.flickr.com/photos/gdguar...57639547178715

[Scroll right for other views]

And how would you go about figuring it out?
---------------------------------------------------
It's a standard beam calculation; however, use 1x4's (3/4" x 3-1/2"
construction grade), get a beer and enjoy your efforts.

BTW, 3, 250 lb people will fit nicely.

Lew

On 1/19/2015 3:12 PM, Lew Hodgett wrote:
It's a standard beam calculation

Any references for this? Someplace I might learn more about the math?

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On 01/20/2015 05:05 AM, Greg Guarino wrote:
On 1/19/2015 3:12 PM, Lew Hodgett wrote:
It's a standard beam calculation

Any references for this? Someplace I might learn more about the math?

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http://www.engineeringcalculator.net...alculator.html


--
"Socialism is a philosophy of failure,the creed of ignorance, and the
gospel of envy, its inherent virtue is the equal sharing of misery"
-Winston Churchill

You are not going to get any twist from a 13 member glue laminate and it will several times stronger than any individual member.


This sucker will hold even three "modern" Americans.

Lew Hodgett wrote:

It's a standard beam calculation
-----------------------------------------------------
"Greg Guarino" wrote:

Any references for this? Someplace I might learn more about the
math?
----------------------------------------------------
This will get you started.

TIP:

If you use a uniform load of 10#/", a 72" bench will have a 720# load.
(ie 3 std adults)


http://tinyurl.com/pxankow


Lew