I am working with 5/8" aluminum and need to know which is stronger, solid rod or tubing and why? Thanks, I know this isn't 4x tech but I figured I stood a better chance of getting the right answer here as opposed to gen chit chat.:D

by bus!:D

You suck! LOL!!:flipoff2:

i dont know the definitive answer but im guessing that to get a good one you will need to elaborate on strength in what scenario :D

but i would say that the tube is stronger in many, but not all cases. for instance in a twist, i believe that the tube is stronger because there are two surface areas that need to break versus just one.

Tube is only stronger than solid by WEIGHT:smokin:

5/8" aluminum bar is far stronger than 5/8" aluminum tube.

It's 6061-T6 rod and I'm using it for camera mounts. The camera is tiny so there really isn't that much load. Everyone kept tlling me that tubing was stronger but for what I'm doing I don't think it will make a difference.

http://www.engineersedge.com/aluminum_plate.htm

Lol, well "everyone" is wrong about tubing being stronger, but it does sound like tubing would probably do the job just fine for your application. Tubing is a lot lighter than solid.

http://www.pirate4x4.com/forum/showthread.php?s=&threadid=6536&highlight=solid+hollow

Solid is generally stronger, except when the un-supported lenght is long enought that it will buckle under its own weight.

i believe that the tube is stronger because there are two surface areas that need to break versus just one.

This is only the case when both surfaces have been heat treated or work hardened, giving them molecular characteristics that are not attainable through stand processes.

People gun drill shafts to save weight, since the core of the shaft has very little affect on the overall strenght.

:)

Damn, where's that ER guy when you need him?? Prolly sucking down donuts at the local coffee shop. :D

If the mass is equal then tubing is stronger, but since you have put the limit to 5/8" diameter tubing or 5/8" diameter solid rod, the rod is obviously going to be stronger, lots more mass there. If it were between 5/8" tubing and an equivalent mass'd (sorry, lack of a better term there) rod, the tubing would be stronger.

And no, mass and weight are not the same, contrary to popular belief.

Originally posted by Sloan
It's 6061-T6 rod and I'm using it for camera mounts. The camera is tiny so there really isn't that much load.

Ken,
For that application it doesn't matter which is stronger; just which is strong enugh. Use 1/8 inch wall tube because the thin stuff takes real talent to weld.

Originally posted by Kendo
And no, mass and weight are not the same, contrary to popular belief.

Please explain above statement

Uh, they ARE the same on Earth.... Not the same in different gravity levels, but on earth, they are the same...

Originally posted by Kendo
Damn, where's that ER guy when you need him?? Prolly sucking down donuts at the local coffee shop. :D

Puhleeze, the whole hollow vs. solid thing is soooo last year :rolleyes: :flipoff2: and I don't like coffee :flipoff2: Now donuts on the other hand... (insert Homer Simpson drooling sound)

And no, mass and weight are not the same, contrary to popular belief.

Please explain above statement

Weight = Mass X Acceleration due to gravity. For the purpose of this discussion however they could be used interchangably.

:beer:

Here's one for ya.... Center of Mass and Center of Gravity are not the same :D

Originally posted by Eric Ruhl



Here's one for ya.... Center of Mass and Center of Gravity are not the same :D

Is anyone else resisting the urge to hurt this guy? :flipoff2:

Is anyone else resisting the urge to hurt this guy?

:p

Originally posted by Eric Ruhl



Here's one for ya.... Center of Mass and Center of Gravity are not the same :D

OK tell me why. Im guessing that is because mass at greater height has less weight as in F=GMm/R^2.

But shiat this is splitting hairs.
:flipoff2:

Sam

Originally posted by twaldher


Is anyone else resisting the urge to hurt this guy? :flipoff2:

http://www.colorado4x4.org/ubb/smilies/spit.gif :flipoff2:

Originally posted by Strange Rover

OK tell me why. Im guessing that is because mass at greater height has less weight as in F=GMm/R^2.

But shiat this is splitting hairs.

Bingo :beer: The difference is almost always negligible on Earth, but this can be a big deal with satellites :)

Simple, put two supports 2' apart. Bridge with tubing, and a solid rod. Now hang 20# load off each in the middle of the span. Which deflects the most? :)

I know when using the lathe, there is a big difference on how much I can overhang the unsupported rod or tube!

For those fans of Statics/Dynamics.... Given a 5/8" rod, at what point, for the same mass, does a tube give the best performance?(i.e. as the tube gets larger and larger, the wall gets thinner and thinner.... to a point you could have a 36" diameter tube with 0.004" wall that wouldn't support a darn thing..... Anyone up to the challange?

I know, you'd rather have a :beer: then think!

Tom :usa:

Originally posted by bgreen


Please explain above statement

What ER has said. When working in the scientific world, you NEVER use the two terms interchangeably, big no-no. Mainly because you do not make assumptions, things like gravity are not to be assumed.

Anyway, that's a little deep for this discussion. :smokin:

For our purposes, we will assume they are the same and continue our debate. :D

If you're just supporting a camera and the diameter HAS to be 5/8", just use the tubing.

look at all the nerds comparing testacle size :flipoff2:

assuming Sloan meant a 5/8" outer diameter rod vs. a 5/8" outer diameter tube of indeterminate inner diameter, then the rod will be stronger. (marginally so, on this scale)

strictly by comparing the relative moments of inertia:

the rod would be (5/16"^4)/4
the tubing would be (5/16"^4)/4 - (1/2 inner diameter)^4)/4

assuming the rod is cheaper (usually) I'd just use the rod.

Originally posted by Sundowner
look at all the nerds comparing testacle size :flipoff2: ..........

the rod would be (5/16"^4)/4
the tubing would be (5/16"^4)/4 - (1/2 inner diameter)^4)/4



Uh huh, I assume you're just throwing your nuts in for comparison then? :D :flipoff2:

Uh huh, I assume you're just throwing your nuts in for comparison then?

scratch em if you got em! :flipoff2:

Originally posted by roundrocktom
For those fans of Statics/Dynamics.... Given a 5/8" rod, at what point, for the same mass, does a tube give the best performance?....Anyone up to the challange?

I know, you'd rather have a :beer: then think!

Tom :usa:

Nothing but a simple maximizing problem, do you remember your calculus?:D

And no I would rather think than have a beer!

For those fans of Statics/Dynamics.... Given a 5/8" rod, at what point, for the same mass, does a tube give the best performance?(i.e. as the tube gets larger and larger, the wall gets thinner and thinner.... to a point you could have a 36" diameter tube with 0.004" wall that wouldn't support a darn thing..... Anyone up to the challange?

I know, you'd rather have a :beer: then think!

Tom :usa: [/B][/QUOTE]


what performance are you looking for, bending, torsion, tension compression? Stiffness or strength?

5/8 round solid or tube?
Go with the one that makes the teensy camera shake less
After all it's about results .
Myself .. I would choose the solid rod because you can drill and tap it, it is also less likely to crush if clamped down too hard.

for your application the rod is the best, because rod will be cheaper and easier to find in that od. tube is just as strong when a twisting force is involved , but solid round can withstand more force under lateral stress because it will not kink then collapse

john godwin
welder and physics major:nuke:

hell as light as almost anything will probably hold it ,sundowner is right. engineers can make the simplest thing difficult:rolleyes:

Ahm bored as hell at work today and hafta toss some shite out. There are two paths you can go by (There will be no playing of Stairway to Heaven):

GEEKY ENGINEER PATH
Assumptions for tube vs. rod problem: OD 5/8" for both, E same-same (that is the elastic modulus of the material) for both, ID varies from 0.0" to 0.625 for the tube, camera mount is simple fixed, canitlever beam arrangment with camera as a point mass at end of the beam

The originator of this thread asked which is stronger, the tube or the rod. What is 'stronger'? Are you asking which will require the most force to break? Without going into stress-strain curves, a simple deflection equation answers that:

Absolute Deflection at beam end = (F*L^3)/(3*E*I)

where 'F' is the force applied (mass of camera times gravity), 'L' is the length of the rod/tube and 'I' is the AREA moment of inertia (ask ER to splain the diff between area and mass moment of intertia ~ oops, I mean gravimetric moment of intertia). Since all these neat terms are constant, we are really only debating the optimization of 1/I. The bigger the 'I', the lower the deflection. What is 'I' you ask? :zzz: :zzz: :zzz:

'I', Area Moment of Inertia of Rod = (pi()*d^4)/64

where 'pi()' is just a little more than 3.1415926 and 'D' is diameter, or 0.625" (in WT units). Now we look at the same for the tube:

'I', Area Moment of Inertia of Tube = ((pi()*(do^2-di^4))/64

where 'do' is the OD of the tube and 'di' is the ID of the tube. It stands to argue that, unless 'di' is zero, the rod will always be stronger.

Now, if by stronger, Sloan means stiffer, then it is a simple question of vibrations:

Stiffness of Cantilever Beam = (3*E*I)/L^3

Now the real concern is whether the floppiness of the camera danging on the end of the tube/beam effects image quality. If the shutter speed of the camera corresponds with the frequency response of this simple beam model, then blurriness will result, so stiffer is better, that is, make 'I' as large as possible

REALITY PATH
I quote the eloquent CRO:

"Myself .. I would choose the solid rod because you can drill and tap it, it is also less likely to crush if clamped down too hard."

God, does that make sense or what?

(note: the aforementioned equations are portable to Excel and MATLAB, should you really want to explore geekdom) :clown: :clown: :clown: