Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old May 20th 20, 11:33 PM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

Will this prevent any sagging at least for 10 years, if not 20+?

Basic idea.
I am building a bookcase primarily of hickory for my reference library. The library consists of the Oxford English Dictionary, Great Books of Western Civilization, various books on programming languages, ...

Calculations of load.
Many of the shelves will be loaded with books for full 4' length and books of 12.5 inches tall by 10 inches wide. That gives a total volume of 6000 cubic inches or 98322.384 cubic centimeters. Based on the specific gravity of paper of 1.2 grams/cubic centimeter, that yields a load of just over 260 pounds. Allowing for 10% safety margin, that is about 290 pounds load per shelf.

Design:
The shelves will be .75" x 11.5" x 48" hickory boards. Under the back for support will be a .5" x 1" x 48" (w x h x l) board. The sides will use standard metal shelf braces. I wish to drill two 3/8 inch holes the full length of the shelves, one in the middle and one an inch back from the front and insert 3/8" diameter stainless steel rods for further bracing.


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Old May 21st 20, 12:37 AM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

On Wednesday, May 20, 2020 at 3:33:54 PM UTC-7, wrote:
Will this prevent any sagging at least for 10 years, if not 20+?

Basic idea.
I am building a bookcase primarily of hickory ...
Design:
The shelves will be .75" x 11.5" x 48" hickory boards. Under the back for support will be a .5" x 1" x 48" (w x h x l) board. The sides will use standard metal shelf braces. I wish to drill two 3/8 inch holes the full length of the shelves, one in the middle and one an inch back from the front and insert 3/8" diameter stainless steel rods for further bracing.


Waste of steel. If you simplly insert a spacer board midshelf that runs from
the top of shelf N to the bottom of shelf N+1, it'll take the center-of-shelf stress
down to the base (and it won't rust). Even cheap wood would work, you can stain
it black so the hickory shows to best advantage.

Steel rods horizontally are floppier than wood, won't be much of a brace. The
use of a steel C section at the back of each shelf might be better (it's the metal
at top edge in compression, and bottom edge in tension, that makes rods
less effective than C sections or the old I-beams.)

If there's a plywood back on the unit, drill for a few pegs to shift the sag stress to that.

Or, you could make two 24" shelves from the 48" boards.
If you must perforate the shelves, a wood dowel or two will keep those
spacers in their place.
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Old May 21st 20, 01:55 AM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

[taliaegh] wrote in message
...

Will this prevent any sagging at least for 10 years, if not 20+?

Basic idea.
I am building a bookcase primarily of hickory for my reference library. The
library consists of the Oxford English Dictionary, Great Books of Western
Civilization, various books on programming languages, ...

Calculations of load.
Many of the shelves will be loaded with books for full 4' length and books
of 12.5 inches tall by 10 inches wide. That gives a total volume of 6000
cubic inches or 98322.384 cubic centimeters. Based on the specific
gravity of paper of 1.2 grams/cubic centimeter, that yields a load of just
over 260 pounds. Allowing for 10% safety margin, that is about 290 pounds
load per shelf.

Design:
The shelves will be .75" x 11.5" x 48" hickory boards. Under the back for
support will be a .5" x 1" x 48" (w x h x l) board. The sides will use
standard metal shelf braces. I wish to drill two 3/8 inch holes the full
length of the shelves, one in the middle and one an inch back from the front
and insert 3/8" diameter stainless steel rods for further bracing.

================================================== ===========

Horizontal 3/8" rods won't prevent sagging for 10 seconds, even if you could
magically drill 48" deep without breaking out through the face of the shelf.
I just went down to the secret laboratory, clamped one end of a 3/8" x 3'
steel rod in the milling machine vise and deflected the other end 4" with my
little finger. All types of steel deflect about the same distance under the
same load, regardless of their hardness.

What you described works in concrete bridges because the steel rods are in
the bottom edges of beams of considerable height, and they are tightened to
resist a pure tension load, not bending.

My heavily loaded wall of book shelves are of 1-1/16" thick x 9" wide red
oak with supports 30" apart, and no sag is visible when sighting down them.
I sawed the logs into 1-1/2" planks hoping for 5/4" finished thickness, but
they cupped during seasoning and 1-1/16" is where the planer cleaned up both
sides of most of them.

https://www.woodbin.com/calcs/sagulator/

The simple fix is to insert upright supports in the middle of the spans.
Mine are simply a friction fit and none have shifted.

What braces the bookcase against tipping sideways?

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Old May 21st 20, 02:53 AM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

On Wed, 20 May 2020 15:33:51 -0700 (PDT), wrote:

Will this prevent any sagging at least for 10 years, if not 20+?

Basic idea.
I am building a bookcase primarily of hickory for my reference library. The library consists of the Oxford English Dictionary, Great Books of Western Civilization, various books on programming languages, ...

Calculations of load.
Many of the shelves will be loaded with books for full 4' length and books of 12.5 inches tall by 10 inches wide. That gives a total volume of 6000 cubic inches or 98322.384 cubic centimeters. Based on the specific gravity of paper of 1.2 grams/cubic centimeter, that yields a load of just over 260 pounds. Allowing for 10% safety margin, that is about 290 pounds load per shelf.

Design:
The shelves will be .75" x 11.5" x 48" hickory boards. Under the back for support will be a .5" x 1" x 48" (w x h x l) board. The sides will use standard metal shelf braces. I wish to drill two 3/8 inch holes the full length of the shelves, one in the middle and one an inch back from the front and insert 3/8" diameter stainless steel rods for further bracing.


You may have some problems with drilling 3/8" holes 4 feet deep and
round rod is not particularly stiff. I wonder whether a different
solution might not be simpler and, perhaps, stronger. For example 3/4"
angle inlayed on the front edge of the shelves. Or even 3/4 inch flat
stock fastened to the front edge with multiple fasteners.
One assumes multiple fasteners along the rear of each shelf to the 1"
rear of the case.
--
cheers,

John B.

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Old May 21st 20, 03:40 AM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

[taliaegh] wrote in message
...

Under the back for support will be a .5" x 1" x 48" (w x h x l) board.

================================================== ==========

Your posting suggests that you have no hands-on experience with the
structural limitations of wood or metal. We all started there. The good
suggestion of doweling intermediate vertical supports, for example, requires
more than beginner skill at woodworking to make the holes align, and
"standard metal shelf braces" includes many types that would be inadequate
for your design load.

Are you planning to build this yourself?



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Old May 21st 20, 04:07 AM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

On Thu, 21 May 2020 08:53:47 +0700, John B.
wrote:

On Wed, 20 May 2020 15:33:51 -0700 (PDT), wrote:

Will this prevent any sagging at least for 10 years, if not 20+?

Basic idea.
I am building a bookcase primarily of hickory for my reference library. The library consists of the Oxford English Dictionary, Great Books of Western Civilization, various books on programming languages, ...

Calculations of load.
Many of the shelves will be loaded with books for full 4' length and books of 12.5 inches tall by 10 inches wide. That gives a total volume of 6000 cubic inches or 98322.384 cubic centimeters. Based on the specific gravity of paper of 1.2 grams/cubic centimeter, that yields a load of just over 260 pounds. Allowing for 10% safety margin, that is about 290 pounds load per shelf.

Design:
The shelves will be .75" x 11.5" x 48" hickory boards. Under the back for support will be a .5" x 1" x 48" (w x h x l) board. The sides will use standard metal shelf braces. I wish to drill two 3/8 inch holes the full length of the shelves, one in the middle and one an inch back from the front and insert 3/8" diameter stainless steel rods for further bracing.


You may have some problems with drilling 3/8" holes 4 feet deep and
round rod is not particularly stiff. I wonder whether a different
solution might not be simpler and, perhaps, stronger. For example 3/4"
angle inlayed on the front edge of the shelves. Or even 3/4 inch flat
stock fastened to the front edge with multiple fasteners.
One assumes multiple fasteners along the rear of each shelf to the 1"
rear of the case.

It's not so much that the rods are stiff - if you use BOLTS and
tension them against the shelf you mightbe able to significantly
increase the bending strength of the shelf - but "gun drilling" a 4
foot shelf is going to be something of a problem, me-thinks.
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Old May 21st 20, 05:07 AM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

On 21/5/20 8:33 am, wrote:
Will this prevent any sagging at least for 10 years, if not 20+?

Basic idea.
I am building a bookcase primarily of hickory for my reference library. The library consists of the Oxford English Dictionary, Great Books of Western Civilization, various books on programming languages, ...

Calculations of load.
Many of the shelves will be loaded with books for full 4' length and books of 12.5 inches tall by 10 inches wide. That gives a total volume of 6000 cubic inches or 98322.384 cubic centimeters. Based on the specific gravity of paper of 1.2 grams/cubic centimeter, that yields a load of just over 260 pounds. Allowing for 10% safety margin, that is about 290 pounds load per shelf.

Design:
The shelves will be .75" x 11.5" x 48" hickory boards. Under the back for support will be a .5" x 1" x 48" (w x h x l) board. The sides will use standard metal shelf braces. I wish to drill two 3/8 inch holes the full length of the shelves, one in the middle and one an inch back from the front and insert 3/8" diameter stainless steel rods for further bracing.



A 3/8" hole through the middle (if you can even get it in the middle) of
a 3/4" piece of timber is going to leave only 3/16" above and below.

No matter how strong and stiff the steel is, the timber shelf will break
away from the steel as soon as you load it up.

CH
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Old May 21st 20, 11:54 AM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

"Clare Snyder" wrote in message
...

It's not so much that the rods are stiff - if you use BOLTS and
tension them against the shelf you mightbe able to significantly
increase the bending strength of the shelf - but "gun drilling" a 4
foot shelf is going to be something of a problem, me-thinks.
==================================================

The metal rods under the steps of a wooden step ladder are good examples of
this.

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Old May 21st 20, 02:03 PM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

On 5/20/2020 8:55 PM, Jim Wilkins wrote:
....

https://www.woodbin.com/calcs/sagulator/
...


Neat!
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Old May 21st 20, 03:21 PM posted to rec.crafts.metalworking
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Default Help with steel rods for heady duty bookcase.

"Bob Engelhardt" wrote in message ...

On 5/20/2020 8:55 PM, Jim Wilkins wrote:
....

https://www.woodbin.com/calcs/sagulator/
...


Neat!
==================
"This calculator can also be used to measure beam deflection. Because beams
are typically positioned on edge, use “thickness” to represent beam depth
and “depth” to represent the thickness of the beam. The shelf span parameter
represents the beam span."



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