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Author Topic: Simplifying M10 suspension  (Read 7106 times)

Craig Hauber

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Re: Simplifying M10 suspension
« Reply #10 on: April 23, 2016, 10:38:18 pm »

Hello!

lm looking for recommendations which would allow me to prebuild suspension cables of exacting length on the ground, and then snap them to the M10 eyebolts preinstalled on the speakers and the ceiling using something like Carabiners.

Thank you all for your time!

Sidhu

Use these:
http://www.adapttechgroup.com/ops-carabiner.html
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Jonathan Kok

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Re: Simplifying M10 suspension
« Reply #11 on: April 27, 2016, 01:36:35 pm »

I have a general question.

Considering pro grade mountaineering equipment, Caribiners would probably be designed to take the load of a, at least, human being, in case of an accident. This considering substantial lateral forces in play also.

Why would they not be considered safe for light rigging ?

Not saying I will use em, Shackles make a lot of sense. But just..

Sidhu
It's a valid question. My understanding is that it has to do with the metallurgy of the products, and how they react to stress in both the short and long term. Specifically, steel has a 'fatigue limit'--the point beyond which, no matter how times it gets used (or, in our industry, vibrated), it WILL NOT fail (barring actual damage to the device). It will weaken, to a point--and then just keep working. This limit is built into the WLL of the products we use.  Aluminum has no limit - if it is continuously used, it WILL eventually fail. And every time it is used, its WLL is lowered.
Most mountaineering equipment is made from aluminum, as a weight savings over steel. But these are regularly in the hands of the users, and inspected frequently--after all, the user's life literally hangs in the balance. An installed speaker is generally only inspected once--upon installation. After that, no-one will look at its rigging again until it's removed. So Aluminum isn't really an option. Steel only. Or Titanium, if you feel like spending more ;)
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Mark Cadwallader

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Re: Simplifying M10 suspension
« Reply #12 on: April 28, 2016, 01:30:17 am »

It's a valid question. My understanding is that it has to do with the metallurgy of the products, and how they react to stress in both the short and long term. Specifically, steel has a 'fatigue limit'--the point beyond which, no matter how times it gets used (or, in our industry, vibrated), it WILL NOT fail (barring actual damage to the device). It will weaken, to a point--and then just keep working. This limit is built into the WLL of the products we use.  Aluminum has no limit - if it is continuously used, it WILL eventually fail. And every time it is used, its WLL is lowered.
Most mountaineering equipment is made from aluminum, as a weight savings over steel. But these are regularly in the hands of the users, and inspected frequently--after all, the user's life literally hangs in the balance. An installed speaker is generally only inspected once--upon installation. After that, no-one will look at its rigging again until it's removed. So Aluminum isn't really an option. Steel only. Or Titanium, if you feel like spending more ;)

I respectfully disagree with your explanation. The following statements are generalizations, and not a technical or engineering analysis, but represent a practical lay explanation.  Steel can, and does, fail under sufficent load. It fails more "gracefully" than aluminum. The failure mode for most aluminum alloys is sudden, with little stretch or elongation before failure. Steel, on the other hand, is more ductile and stretches much more before it fails.  As an example, a steel bolt that is over-torqued will gradually stretch in length (while reducing its diameter). With enough torque, it will fail. One can feel "the give" as the bolt is tightened. A similar aluminum bolt (yes, they exist) will stretch very little before it fails (snaps off). With a shock load, steel will deform much more than aluminum before failure. That greater deformation can allow the user to see the pre-failure effect of overloading something made of steel more something made of equally-strong aluminum in a pre-failure mode.
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John Rutirasiri

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Re: Simplifying M10 suspension
« Reply #13 on: April 28, 2016, 10:50:37 am »

Steel, on the other hand, is more ductile and stretches much more before it fails.  As an example, a steel bolt that is over-torqued will gradually stretch in length (while reducing its diameter). With enough torque, it will fail. One can feel "the give" as the bolt is tightened. A similar aluminum bolt (yes, they exist) will stretch very little before it fails (snaps off). With a shock load, steel will deform much more than aluminum before failure. That greater deformation can allow the user to see the pre-failure effect of overloading something made of steel more something made of equally-strong aluminum in a pre-failure mode.

It depends on the carbon content of the steel and how it was heat-treated.  High carbon steel is hard but not very ductile, and quenched carbon steel is much more brittle than annealed or quenched+tempered steel.  Which is why you don't really see high carbon steel used for bolts.

John R.
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Jonathan Kok

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Re: Simplifying M10 suspension
« Reply #14 on: May 03, 2016, 11:40:37 am »

I respectfully disagree with your explanation. The following statements are generalizations, and not a technical or engineering analysis, but represent a practical lay explanation.  Steel can, and does, fail under sufficent load. It fails more "gracefully" than aluminum. The failure mode for most aluminum alloys is sudden, with little stretch or elongation before failure. Steel, on the other hand, is more ductile and stretches much more before it fails.  As an example, a steel bolt that is over-torqued will gradually stretch in length (while reducing its diameter). With enough torque, it will fail. One can feel "the give" as the bolt is tightened. A similar aluminum bolt (yes, they exist) will stretch very little before it fails (snaps off). With a shock load, steel will deform much more than aluminum before failure. That greater deformation can allow the user to see the pre-failure effect of overloading something made of steel more something made of equally-strong aluminum in a pre-failure mode.
You're note specificially says 'overtorqued'. Perhaps I should have made it more clear; my assumption was that the product was being used within specification. Thus, my note regarding 'barring actual damage to the device'. Of course, overloading, overtorquing, or otherwise exceeding the specifications of anything will cause it to fail. The point, however, was that, used within specification, a properly-maintained steel device will NEVER fail. An aluminum device, however, WILL(...eventually...). I would say that THIS (fatigue limit) is the reason aluminum is not used for overhead lifting. The fact that steel stretches before failure is an added benefit, and may be a part of the reason it is used. After all, a steel device that has been used beyond its WLL will show damage long before an aluminum device will. But what if the device never exceeds it WLL? Why can't I use aluminum?
My initial thought was the same as yours; steel stretches before breaking. But the more I thought about it, the more I realized, that can't be the only reason. After all, so long as I use an aluminum device that will never exceed its limit (for example, for a permanent installation), it  should be fine. Except it won't. I'm not saying it WILL fail; but it CAN fail. Even though it was within spec when installed. With the weights we deal with, this failure point may be a hundred or more years in the future, but it exists, and is inherent to aluminum.
« Last Edit: May 03, 2016, 11:54:00 am by Jonathan Kok »
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John Rutirasiri

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Re: Simplifying M10 suspension
« Reply #15 on: May 03, 2016, 01:36:39 pm »

The reason is simple:  steel, given same physical size (i.e. M10 bolt) , has 5-10x higher yield and tensile strength than aluminum alloy.  It is a higher density material.

Alunimum (alloy) is used in "overhead lifting" all the time:  trusses are aluminum.  The sound wings on a mobile stage like SL100 are aluminum.  But those things do not experience as much dynamic shock as lifting hardware like shackles, which are almost alway steel or alloys of.

Steel doesn't last forever.  It corrodes even if "properly maintained" from galvanic corrosion, which can happen below a painted surface.

John R.



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Jonathan Kok

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Re: Simplifying M10 suspension
« Reply #16 on: May 03, 2016, 07:37:56 pm »

The reason is simple:  steel, given same physical size (i.e. M10 bolt) , has 5-10x higher yield and tensile strength than aluminum alloy.  It is a higher density material.
...but given a similar initial weight rating, the yield and tensile strength become irrelevant. Both are rated for the same thing. So why not aluminum? Again, we're talking about NOT exceeding weight ratings. Always staying within the WLL.
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Alunimum (alloy) is used in "overhead lifting" all the time:  trusses are aluminum.  The sound wings on a mobile stage like SL100 are aluminum.  But those things do not experience as much dynamic shock as lifting hardware like shackles, which are almost alway steel or alloys of.
Good point. There's plenty of things that are aluminum.  That still doesn't explain why a steel device can be used in rigging, and an aluminum device cannot. Again, staying within the WLL of either device.
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Steel doesn't last forever.  It corrodes even if "properly maintained" from galvanic corrosion, which can happen below a painted surface.
John R.
I agree. Real world, steel will eventually fail as well.  But regular inspection will show this. An inspection of an aluminum device will show nothing.

Ultimately, my point is, it cannot only be because steel will stretch before breaking. Because if it DOES stretch, you've exceeded its design specifications. I agree, that is absolutely a benefit--in that, it can be obvious when a steel device has exceeded its WLL. But again, not exceeding WLL, you still can't use aluminum.

At least we agree that it's a no-no ;)
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Brent_Handy

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Re: Simplifying M10 suspension
« Reply #17 on: May 08, 2016, 09:08:26 pm »

I have not read all of the replies.  We follow the construction industry.  We use Gripples.  Gripples save lots of time, money and stress.  You do not need to pre-engineer your cables on the ground with Gripple.
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David Sturzenbecher

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Re: Simplifying M10 suspension
« Reply #18 on: May 08, 2016, 10:23:45 pm »

I have not read all of the replies.  We follow the construction industry.  We use Gripples.  Gripples save lots of time, money and stress.  You do not need to pre-engineer your cables on the ground with Gripple.

I had my mechanical engineer call out Gripples for saftey cables once,  not sure if we got a bad batch, cheap model,  or what, but they were absolute junk.   I told my ME that if he used them again he would have install them. He decided to use them again, and I made him get on a plane and deal with them on site... he doesn't call them out anymore. The main issue is that they would not release under any circumstance, correct tool or not.
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Dave Garoutte

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Re: Simplifying M10 suspension
« Reply #19 on: June 24, 2016, 05:48:23 pm »

Different alloys of aluminum and steel behave differently.
There are ductile aluminums and brittle steels.
Generally the harder the material, the less ductile it is, and the higher the yield point and tensile strength.  This is true for both aluminum and steel.

Climbing caribiners are aluminum because the climber has to carry lots of them.  They are strong enough and can be replaced if overloaded.

Hanging a mass overhead is not somewhere that the weight of the fastener should be ever be considered over the strength.

Aluminum has a fatigue life that is related to the stresses applied. The loads can be well below the yield point of the material but it will still eventually fail, though it may be millions of cycles.
Steel has an essentially infinite fatigue life if the loads are below the yield point for the given alloy. 
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Re: Simplifying M10 suspension
« Reply #19 on: June 24, 2016, 05:48:23 pm »


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