"Z3Driver" wrote:
> I'm building a climbing toy for my granddaughter and need to give
> some scientific assurances to grannie that the 1" dowels spanning
> 36" will more than adequately support her weight. Is there a
> formula to calculate breaking point based on weight?
--------------------------------------
Yes there is, but an even easier solution.
Take a look at a wooden closet rod.
Most are at least 1-1/8" dia.
Most are bent.
How heavy is the child?
I'd be looking at schedule 40 black pipe, at least 1-1/4".
Lew
UPDATE:
------------------------------
"Z3Driver" wrote:
> I'm building a climbing toy for my granddaughter and need to give
> some scientific assurances to grannie that the 1" dowels spanning
> 36" will more than adequately support her weight. Is there a
> formula to calculate breaking point based on weight?
--------------------------------------
I previously wrote:
> Yes there is, but an even easier solution.
>
> Take a look at a wooden closet rod.
>
> Most are at least 1-1/8" dia.
>
> Most are bent.
>
> How heavy is the child?
>
> I'd be looking at schedule 40 black pipe, at least 1-1/4".
---------------------------------------
The 36" unsupported length is the fly in the ointment.
A ladder rung has an unsupported length of 12"-16".
Big difference.
Want to use smaller dia. rungs, add more supports.
Since the "styles" are in compression, not much material is needed.
Lew
"Swingman" wrote
>
> There is no need to drill holes in the uprights. There are pipe/rod
> holders of different diameters which can be screwed to the uprights to
> hold the appropriate diameter black pipe.
>
> To the OP's question: there is NO way in hell I would use wooden dowels,
> of ANY diameter, in a 36" span for ANY child's "climbing toy".
>
------------------------
All this talk of building "climbing toys", dowels, pipes, etc. bring back
memories of the "children toys" my grandfather built for us kids. We lived
with him for a couple years and when we were moving in, he decided we needed
some kind of play set in the back yard. He built lots of pole buildings and
had fallen some trees and debarked them. The had be drying out under a roof
of an open pole structure.
He took these Poles, some of them at least 14" in diameter, and put them in
big holes in the ground. They were packed with shale and pounded into a
semi cement state. Two of the poles were at least 35 feet tall. By
attaching some large planks across the top, this became the swing set. And
by putting some more large poles in the ground around it, he created some
gymnastic bars, monkey bars, ladders, etc. All were recycled pipe. He just
drilled out holes in the logs, inserted the pipes and installed them in the
ground.
The bottoms were treated with creosote, not done on children's toys now!
These things went into the ground and stayed upright and solid for over
thirty years. The original rope for the swing was good for over twenty
years. It was only removed to add on to the house.
I should also mention that it snowed there and we used a big tractor with a
blade on the front to remove the snow. This big playground set was right
next to where we shoved the snow out of the way. So we had a huge snow fort
next to the monster playground set. We would go nuts with that particular
combination.
We live in a world full of pussy, wimp toys. No wonder the kids are turning
out the way they are. Real, substantial toys built bodies and character!
When I went to school from this environment, it was a country school where
athletic shoes were unknown. We played soccer in logging boots. I was
personally responsible for the death of several soccer balls. Damn, all
this talk of my childhood is wearing me out!
Don't mind me. I am going back into my traditional curmudgeon mode now.
<snooze>
Lee
"Swingman" <[email protected]> wrote
>
> AAMOF, just turned down a nice, and normally potentially very
> profitable, cabinet job - some Tansu cabinets (like the kind I built for
> my office on my website) for a kid's play area in their home - uh huh,
> NOT me!
>
WIMP!! :-)
>
> Didja get that puppy yet? Pictures if you got'em. :)
>
Another week. I still have to puppy proof the fence.
On 2011-07-08 13:39:01 -0400, GROVER <[email protected]> said:
> When I was a kid, I had to walk 5 miles to school in the snow, both
> ways up hill.
Yeh, barefoot, too, with barbed wire wrapped around your feet for traction.
On 7/7/2011 8:05 PM, Z3Driver wrote:
> I'm building a climbing toy for my granddaughter and need to give some
> scientific assurances to grannie that the 1" dowels spanning 36" will
> more than adequately support her weight. Is there a formula to calculate
> breaking point based on weight?
Thanks for all the quick replies. I think Leon and Larry offered some
good advice to add a stiffener in the middle. Looks like my Forstners
are going to get a good workout this weekend.
On 7/8/2011 11:12 AM, Lee Michaels wrote:
>
>
> "Swingman" wrote
>> To the OP's question: there is NO way in hell I would use wooden
>> dowels, of ANY diameter, in a 36" span for ANY child's "climbing toy".
> We live in a world full of pussy, wimp toys. No wonder the kids are
> turning out the way they are. Real, substantial toys built bodies and
> character! When I went to school from this environment, it was a country
> school where athletic shoes were unknown. We played soccer in logging
> boots. I was personally responsible for the death of several soccer
> balls. Damn, all this talk of my childhood is wearing me out!
>
> Don't mind me. I am going back into my traditional curmudgeon mode now.
> <snooze>
LOL ... I agree wholeheartedly, but ... and it's a big BUT.
There were fewer LAWYERS in our less litigious childhood, and even most
of those lawyers (and parents) back then had old fashioned values and
common sense.
With regard to lawyers, it is a dead certainly that is no longer the case.
It's not so much what you do for your kids/grand kids, it's their
friends, or their kid's friends, who will be using your kids/grand kids
homemade toy ... and guess who gets sued.
It happens on a daily basis.
AAMOF, just turned down a nice, and normally potentially very
profitable, cabinet job - some Tansu cabinets (like the kind I built for
my office on my website) for a kid's play area in their home - uh huh,
NOT me!
I'm sure I could figure out a way to keep it from tumbling down when
their kid, or one of his friends, decided to climb Mt Everest in the
playroom, but by that time it would be way over the budget, and with no
guarantees.
30 years ago I wouldn't have hesitated. Unfortunately, it's the times we
live in ....
Didja get that puppy yet? Pictures if you got'em. :)
--
www.e-woodshop.net
Last update: 4/15/2010
KarlC@ (the obvious)
In article <[email protected]>, [email protected] says...
>
> I'm building a climbing toy for my granddaughter and need to give some
> scientific assurances to grannie that the 1" dowels spanning 36" will
> more than adequately support her weight. Is there a formula to
> calculate breaking point based on weight?
<http://www.engineeringcalculator.net/beam_calculator.html>
You'll need a moment of inertia
<http://www.engineeringcalculator.net/cross_section_properties.html>
And you'll need the elastic modulus for the wood
<http://www.conradfp.com/pdfs/ch4-Mechanical-Properties-of-Wood.pdf>
Or make up a sample and see how much weight it takes to break it.
Look at a wood ladder - the slot cut out is filled with the foot board.
So the side board is solid top to bottom. No voids. And there is a
metal rod that bolts the two sides to each other keeping the tread
inside the slot made for them.
They are designed for specific angles. And side loads are nominal
or the ladder falls.
Martin
On 7/7/2011 9:29 PM, Mike Marlow wrote:
> Martin Eastburn wrote:
>> The rods might not be the issue - but the holder of the rods - stiles
>> ? having holes within - being strong in the angle to the ground they
>> are in.
>> Putting black pipe (galvanize can cut bare feet...) might be perfect
>> but if the 'stiles' are not - the ladder will fail anyway.
>>
>
> Of course, he could under-design the ladder, but there are way too many
> wooden ladders out there to suggest that the rails are going to be weakened
> by drilling holes for the rungs. Not to mention the millions of people who
> have built tree stands and like climbing devices with no problems.
>
> I don't know what the math works out to when it comes to designing a ladder
> like this, but I do know that the rails of a ladder can be compromised a lot
> by a hole for a rung, and not weaken the ladder. Maybe that's because the
> rung fills in the hole and restores the strength.
>
Martin Eastburn wrote:
> The rods might not be the issue - but the holder of the rods - stiles
> ? having holes within - being strong in the angle to the ground they
> are in.
> Putting black pipe (galvanize can cut bare feet...) might be perfect
> but if the 'stiles' are not - the ladder will fail anyway.
>
Of course, he could under-design the ladder, but there are way too many
wooden ladders out there to suggest that the rails are going to be weakened
by drilling holes for the rungs. Not to mention the millions of people who
have built tree stands and like climbing devices with no problems.
I don't know what the math works out to when it comes to designing a ladder
like this, but I do know that the rails of a ladder can be compromised a lot
by a hole for a rung, and not weaken the ladder. Maybe that's because the
rung fills in the hole and restores the strength.
--
-Mike-
[email protected]
On Jul 8, 12:12=A0pm, "Lee Michaels" <leemichaels*nadaspam* at comcast
dot net> wrote:
> "Swingman" =A0wrote
>
> > There is no need to drill holes in the uprights. There are pipe/rod
> > holders of different diameters which can be screwed to the uprights to
> > hold the appropriate diameter black pipe.
>
> > To the OP's question: there is NO way in hell I would use wooden dowels=
,
> > of ANY diameter, in a 36" span for ANY child's "climbing toy".
>
> ------------------------
> All this talk of building "climbing toys", dowels, pipes, etc. bring back
> memories of the "children toys" my grandfather built for us kids. =A0We l=
ived
> with him for a couple years and when we were moving in, he decided we nee=
ded
> some kind of play set in the back yard. =A0He built lots of pole building=
s and
> had fallen some trees and debarked them. The had be drying out under a ro=
of
> of an open pole structure.
>
> He took these Poles, some of them at least 14" in diameter, and put them =
in
> big holes in the ground. =A0They were packed with shale and pounded into =
a
> semi cement state. =A0Two of the poles were at least 35 feet tall. =A0By
> attaching some large planks across the top, this became the swing set. =
=A0And
> by putting some more large poles in the ground around it, he created some
> gymnastic bars, monkey bars, ladders, etc. =A0All were recycled pipe. =A0=
He just
> drilled out holes in the logs, inserted the pipes and installed them in t=
he
> ground.
>
> The bottoms were treated with creosote, not done on children's toys now!
> These things went into the ground and stayed upright and solid for over
> thirty years. =A0The original rope for the swing was good for over twenty
> years. =A0It was only removed to add on to the house.
>
> I should also mention that it snowed there and we used a big tractor with=
a
> blade on the front to remove the snow. =A0This big playground set was rig=
ht
> next to where we shoved the snow out of the way. =A0So we had a huge snow=
fort
> next to the monster playground set. =A0We would go nuts with that particu=
lar
> combination.
>
> We live in a world full of pussy, wimp toys. =A0No wonder the kids are tu=
rning
> out the way they are. =A0Real, substantial toys built bodies and characte=
r!
> When I went to school from this environment, it was a country school wher=
e
> athletic shoes were unknown. =A0We played soccer in logging boots. =A0I w=
as
> personally responsible for the death of several soccer balls. =A0Damn, al=
l
> this talk of my childhood is wearing me out!
>
> Don't mind me. =A0I am going back into my traditional curmudgeon mode now=
.
> <snooze>
>
> Lee
When I was a kid, I had to walk 5 miles to school in the snow, both
ways up hill.
JoeG
On 7/7/2011 8:05 PM, Z3Driver wrote:
> I'm building a climbing toy for my granddaughter and need to give some
> scientific assurances to grannie that the 1" dowels spanning 36" will
> more than adequately support her weight. Is there a formula to calculate
> breaking point based on weight?
I wouldn't, suppose a bigger kid gets on it. Suppose she slips and
falls down to the next step and dowel breaks with a sharp pointy end
sticking out. At the very least run a support through the center and
use a larger dowel.
On Jul 7, 9:05=A0pm, Z3Driver <[email protected]> wrote:
>
> I'm building a climbing toy for my granddaughter and need to give some
> scientific assurances to grannie that the 1" dowels spanning 36" will
> more than adequately support her weight. =A0Is there a formula to
> calculate breaking point based on weight?
Yes, there are such formulas, but in reality, and in your situation,
they're pretty much useless. Many variables, etc., etc.
Test the device yourself. There should always be a factor of safety
of 3x or 4x - that's what they do on ladders, and what you're building
is a ladder. If it can hold you, it can safely hold the grandkid.
R
On Thu, 07 Jul 2011 20:05:19 -0500, Z3Driver <[email protected]> wrote:
>I'm building a climbing toy for my granddaughter and need to give some
>scientific assurances to grannie that the 1" dowels spanning 36" will
>more than adequately support her weight. Is there a formula to
>calculate breaking point based on weight?
Granny is smart. Little boys kick at things like that, jump up and
down on them, etc., so your granddaughter might climb up a ruined
ladder some day and pay for it.
See if these help. (I didn't review them.)
http://www.worldwideflood.com/ark/design_calculations/wood_strength.htm
http://www.fpl.fs.fed.us/documnts/pdf2001/green01d.pdf
P.S: I'd put a stiffener in the middle so the dowel only had a 17"
span. Then they might support adults, too, especially if they're oak,
ash, or hickory dowels.
http://www.midwestdowel.com/
http://www.atlasdowel.com/pages/products/default/5/
http://goo.gl/7NDWa by the hundred (Ouch!)
--
Happiness lies in the joy of achievement and the thrill of creative effort.
-- Franklin D. Roosevelt
The rods might not be the issue - but the holder of the rods - stiles ?
having holes within - being strong in the angle to the ground they are in.
Putting black pipe (galvanize can cut bare feet...) might be perfect
but if the 'stiles' are not - the ladder will fail anyway.
Martin
On 7/7/2011 8:05 PM, Z3Driver wrote:
> I'm building a climbing toy for my granddaughter and need to give some
> scientific assurances to grannie that the 1" dowels spanning 36" will
> more than adequately support her weight. Is there a formula to calculate
> breaking point based on weight?
On 7/7/2011 9:06 PM, Martin Eastburn wrote:
> The rods might not be the issue - but the holder of the rods - stiles ?
> having holes within - being strong in the angle to the ground they are in.
>
> Putting black pipe (galvanize can cut bare feet...) might be perfect
> but if the 'stiles' are not - the ladder will fail anyway.
>
> Martin
>
> On 7/7/2011 8:05 PM, Z3Driver wrote:
>> I'm building a climbing toy for my granddaughter and need to give some
>> scientific assurances to grannie that the 1" dowels spanning 36" will
>> more than adequately support her weight. Is there a formula to calculate
>> breaking point based on weight?
There is no need to drill holes in the uprights. There are pipe/rod
holders of different diameters which can be screwed to the uprights to
hold the appropriate diameter black pipe.
To the OP's question: there is NO way in hell I would use wooden dowels,
of ANY diameter, in a 36" span for ANY child's "climbing toy".
--
www.e-woodshop.net
Last update: 4/15/2010
KarlC@ (the obvious)