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Lumber storage How strong is conduit?

KzooRichie's picture

I''m thinking of building a wall mounted lumber rack of conduit, probably 3/4 or 1". I'm thinking it would be a cheap way to go. Is it strong enough? Any advice or ideas would be appreciated.

alanjg's picture

(post #84816, reply #1 of 22)

Use black pipe.


remember there's a safety consideration to take into account


Alan


http://www.alan-goldberg.com/

JohnWW's picture

(post #84816, reply #2 of 22)

It would very much depend on the specifics of the design.


John White, Shop Manager, Fine Woodworking Magazine

John White Shop Manager for FWW Magazine, 1998 to 2007

nikkiwood's picture

(post #84816, reply #3 of 22)

I assume you are talking about regular electrical conduit (EMT).

If so, unless each shelf is going to carry a light load, I don't think I would hazard it.

Much better to use black pipe.

I have built several large lumber racks using pipe that I picked up for a song at scrap yard -- some black (preferred) and some galvanized.

********************************************************
"It is what we learn after we think we know it all, that counts."

John Wooden 1910-

******************************************************** "It is what we learn after we think we know it all, that counts." John Wooden 1910-
forestgirl's picture

(post #84816, reply #4 of 22)

Like John said, no details to answer, but here's a link to my lumber rack.  Adjustable pipe supports, about 15" long.  Has held up for several years now.


That's a 2005 pic, there's more on it now.  Those 2 walnut slabs weight a bunch!  (get away, Sarge!)


 



forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 


Edited 1/29/2007 7:39 pm by forestgirl

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

highfigh's picture

(post #84816, reply #6 of 22)

What is that plastic basket doing on your lumber rack? Your small scraps would take up less space if you made the container for them, from them.

"I cut this piece four times and it's still too short."

"I cut this piece four times and it's still too short."
forestgirl's picture

(post #84816, reply #7 of 22)

Picky, picky picky! ;-)  That was where I tossed some project pieces and info for little display things I made awhile back.  Just getting them out of the way and in one place.

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

Jfrostjr's picture

(post #84816, reply #8 of 22)

Really nice set of pictures and an excellent description.

Frosty

SARGEgrinder47's picture

(post #84816, reply #10 of 22)

Nice walnut slabs you have there FG.. When did you say your next vacation that takes you out of town was? :>)


Regards...


Sarge.. jt

Sarge..

Woodworkers' Guild of Georgia

forestgirl's picture

(post #84816, reply #11 of 22)

Ach!  I knew it!!  He just never gives up, LOL.

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-) 

SARGEgrinder47's picture

(post #84816, reply #13 of 22)

I'm sincerely hope that ToolDoc is somewhere laughing at my continued efforts to get that slab and your continued efforts to keep it. Even though I bet he's putting his money on you keeping it! Regardless.. we "rocked with Doc" while the music played! ha.. ha...


Regards..


Sarge.. jt

Sarge..

Woodworkers' Guild of Georgia

Thew's picture

(post #84816, reply #5 of 22)

I have a very similar rack to Forestgirl's, and I have had no issue with 1" EMT. I have stacked 12" deep by 10" tall without an issue. The method of attaching the EMT to the support is more critical than the pipe bending.

Thew

RickL's picture

(post #84816, reply #9 of 22)

Conduit is fine. Folks are confusing it with the thin wall EMT. We had racks with conduit arms and were supporting brass rods and bars and brass is ten times heavier than wood.


Apparently very few folks read all the posts here. EMT is totally different then conduit which is available in medium and heavy duty. The conduit would be closer to black pipe and cheaper.


Edited 1/31/2007 7:48 am ET by RickL

tuolumne's picture

(post #84816, reply #12 of 22)

This worked pretty well for me... I used 3/4" galvanized conduit, which can be had much cheaper than black iron.  As a structural engineer, you can be sure I ran the numbers and verified load capacity.  My pipes are 20" long and set nearly 3" into the 4x4 support posts; just over 17" projection and they are plenty stiff.  I drilled the holes at about 3 degrees above level to prevent any pipes from slipping out.  The 4x4 run from floor to ceiling in my basement shop at 32" on center.   I drilled holes at 6" on center vertically to provide lots of configurations.  The 4x4s are also set around 12" off the wall to allow plywood storage behind the lumber rack.


Edit:  By the way, the lumber load creates a large load that will tend to thrust the bottom of the supports towards the wall and pull the top into the room.  I used PT 2x4s at the bottom to brace back to the wall (these also keep the plywood off the floor), and securely lagged the top of the posts to the floor joists above.


Edited 1/30/2007 1:09 pm ET by tuolumne

nikkiwood's picture

(post #84816, reply #14 of 22)

Let me take advantage of your engineering know-how .............

With the 3/4" galvanized conduit you used, is this indeed plain old electrical conduit that's labeled EMT? Strength wise, how does it compare to either 1/2" (ID) black or galvanived pipe?

Thanks.

********************************************************
"It is what we learn after we think we know it all, that counts."

John Wooden 1910-

******************************************************** "It is what we learn after we think we know it all, that counts." John Wooden 1910-
tuolumne's picture

(post #84816, reply #15 of 22)

You'll have to answer a few questions for me first.  The pipe I used is the thin wall stuff - .065" wall and 1.05" o.d.   Two compare the strength of the two, I need to know the o.d. and wall thickness of 1/2" black iron pipe.


Strength of the pipe is based on something we refer to as the Section Modulus (S) and the yielding stress of the material (fy).  Deflection is governed by a section property called the Moment of Inertia (I) and the Modulus of Elasticity (E) of the material.  For all grades of steel, E is largely unchanged.  However, fy can vary a good deal.


For the EMT - deflection on a 16" cantilever with a 100 lb load would be approximately 1/8".  Overstess (with safety factor) would occur when a 200 lb man hangs on the end of a 24" pipe.  Deflection at that point would be closer to 3/4".


Send me the dimensions of the black iron and we can compare the capacity. 


Edit:  I just looked up EMT properties, and I guess the stuff I'm using is not EMT, but conduit which has a thicker wall.  3/4" EMT has a wall thicknes of 0.049" and an o.d. of 0.922".  In the above scenario, a 100 lb load at 16" would yield a 3/8" deflection and overstressed condition.  With posts at 32" o.c. this would be reflective of a stack of dry oak 12"x12"...so even EMT can be used for a lumber rack with discretion.


Edited 1/30/2007 3:24 pm ET by tuolumne

BruceS's picture

(post #84816, reply #16 of 22)

Boy, You can crunch all the numbers about EMT strength you want,  But I can take a 2 foot length  and bend it over my knee to a 45 easily.  It is too easy to stack up 500,600,1000 lbs. without realizing the weight on the rack.   Where is the "Safety factor" ? 

Work Safe,  Count to 10 when your done for the day !!


Bruce S. 


 

Work Safe,  Count to 10 when your done for the day !!

Bruce S. 

 

Quickstep's picture

(post #84816, reply #17 of 22)

On a similar note, my concern about emt conduit is that when it's strength is exceeded, it kinks, causing the failure to be catastrophic. Some of it also has a seam which is prone to sudden failure.

nikkiwood's picture

(post #84816, reply #18 of 22)

The pipe I used came from a scrap yard, and it was standard black pipe -- 1/2" ID, and the OD must have been about 3/4" (IIRC, I used a 15/16" bit for the holes). I would guess the pipe wall is about 1/8".

I cut it up into 16" sections, mounted it on 2X4's set 16" O/C (so each pipe provides about 12" of stacking space), and the holes were drilled at 3°.

Does that give you the info you need?

I have some very heavy lumber (mostly white oak), stacked on some of these "shelves", and it would make me very nervous to use EMT.

Thanks again.

********************************************************
"It is what we learn after we think we know it all, that counts."

John Wooden 1910-

******************************************************** "It is what we learn after we think we know it all, that counts." John Wooden 1910-
tuolumne's picture

(post #84816, reply #20 of 22)

Again, what I used was not EMT, but galvanized conduit.  Don't use EMT!!


Your pipe has a slightly greater S and a slightly lower I.  What that means, is greater strength before failure, but also larger deflections.  For the 100 pound load at 16", deflection for 1/2" black iron would be about 3/8" vs. 1/8" for the conduit.  Technically, the black iron is already yielding at this point.  The materail may not fail, but too much load will create permanent deflection even once removed.


What this says is that 3/4" galv. conduit will definately out-perform 1/2" black iron in this function.  Either one can support a stack of white oak 16" wide and 24" tall without any strength issues (pipe spacing 32" o.c.)  If your pipes are closure it they could support more.  In reality, I don't stack any of my lumber over 12" or it would be too hard to access.  If I actually have more than that of a given species, I'll start a fresh row.

nikkiwood's picture

(post #84816, reply #22 of 22)

Thanks once more........

I am very familiar with EMT (which is also galvanized), which I've used as conduit for wiring, but I will have to look more closely at what you refer to as as plain "conduit."

********************************************************
"It is what we learn after we think we know it all, that counts."

John Wooden 1910-

******************************************************** "It is what we learn after we think we know it all, that counts." John Wooden 1910-
MikeHennessy's picture

(post #84816, reply #19 of 22)

"I just looked up EMT properties, and I guess the stuff I'm using is not EMT, but conduit which has a thicker wall. "


EMT, also known as "thinwall couduit", is designed to be bendable. You can use a bender with an arm as short as 12" and bend this stuff pretty easily. It's manually bent on-site as required. I would definately NOT use it as a lumber rack. (Although it does hold up tomato plants quite nicely! <G>) What you probably used is thick wall conduit -- galvanized steel pipe that's thicker than EMT, but thinner than galvanized plumbing pipe. It is not designed to be bendable. Instead, fittings are used to turn corners.


Mike Hennessy
Pittsburgh, PA

Mike Hennessy
Pittsburgh, PA
Everything fits, until you put glue on it.

tuolumne's picture

(post #84816, reply #21 of 22)

That's right, don't use EMT.  If you can't run the numbers, do the old ape hanging trick from your pipe before you load it up and compare your own weight to what you intend to load the rack with.  Common sense worked for structural engineers for nearly 6000 years until the computer was invented.