Evan Kirkendall wrote on Fri, 16 May 2008 19:38

Mark, You also have to think about jumping on a case vs. a static load. Evan

Jump or step? Which was it? Little help?

My 30" jump test of a weight 25% above the reported crush weight came 1/2 a ton short of producing a significantly less than sufficent force to shove the rubber feet through the bottom of the case.

Seriously... we're trying to figure out what sort of "step" or "jump" or ??? event produced your reported outcome of shoving the rubber feet through the bottom of the case.

[Updated on: Fri, 16 May 2008 22:56]

Mike Pyle wrote on Fri, 16 May 2008 23:19

I'm guessing the guy was moonlighting from his regular job at UPS.

I think I had the same UPS guy - in his day job.

I just got one of my Sabines back from warranty service (another customer focused, very responsive company) with a "detached" internal power supply.

It had to be an unusual amount of force to snap the mounts. (unit still works 100%!!)

[Updated on: Sun, 18 May 2008 12:10]

[Updated on: Sun, 18 May 2008 12:10]

[Updated on: Sat, 17 May 2008 13:05]

[Updated on: Sun, 18 May 2008 12:11]

What would be nice is if they used 1/4" baltic birch plywood for those small cases instead of the standard pine plywood. It'd add a few dollars and a pound or two additional weight, but would be substantially stronger.

Back in the day at Hard Truckers, we built all the cases using either 3/8" or 1/2" baltic birch, depending on the use. And for maximum protection versions, we bonded that thin "pebble" finish sheet aluminum to the plywood, sometimes even anodizing them in different colors. Here's both a plain and a gold anodized version:

John

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Evan Kirkendall wrote on Fri, 16 May 2008 21:38

Mark, You also have to think about jumping on a case vs. a static load. The load you had pressing on the case was evenly distributed throughout the whole case and the load was increased steadily, and slowly. If you were to jump onto the case, that force is focused on a much smaller area and all the weight is coming at once. For example, take a 2x4 and suspend it in mid air. If you start off with a small weight, and increase it slowly the board will take a lot of weight before failure. Now, if you take that weight you started with, and drop it from a few feet above, I'd bet money that the board would break. So, with the mic case sitting at the foot of the stage, say the person steps down from the stage(lets say like 3'), they are traveling a lot faster, and that 160lbs becomes a lot more damaging. Again, I do not know if the person was stepping up or down, but we can assume what we want. However, with that said, the case still did it's job. It protected all of the mics and DI's inside of it and stood up to the damage. That case was also dropped during a load in a few weeks before and survived just fine. It slid off a guitar cab and landed on it's corner on the pavement. The lid was bent a little, but otherwise it was fine. And, as I said before: shit happens. I'll be buying plenty more EWI products in the future(just ordered 2 snakes today!), dont worry about that. Im not out to discourage sales, I just want to let people know about my failures. Thanks again Mark. Evan

Thanx for the physics..

I find it hard to believe that damage was caused by an individual using it as a step.

"He was only around 160lbs, and it was just one step. "

Looking at it from the cases perspective, what shape do you think your foot would be in after hitting it with that case hard enough to do that damage? Now that would be an interesting test. (just kidding, seriously don't try that).

Jumping on it from a height of 1 meter is a different story. The acceleration of gravity will get you moving at a velocity of roughly 4.5 meters/second. The kinetic energy is over 700 joules. Now the force this exerts upon landing is a little tricky. It depends a lot on how how fast you stop, or how rigid the surface is. If you think about this, stopping instantly is effectively infinite negative acceleration. That's why running your car into a brick wall does more damage than running into the garage door that gives some.

So the equivalent static weight is a rough guess or a range, but if deceleration is rapid, 500#-1000# or more sounds plausible. Somebody who knows this stuff should check my work, it's been decades since I cracked a physics book.

You casually mention the case was "dropped" once. Could that be the damaging event? How high, and what was it dropped on? Did you see the actual damage occur?

I suspect no case is Evan-proof, they'd be too heavy to lift. I feel bad for Mark having to defend the integrity of his product against a claimed single 160# footstep. That sounds pretty puny if we accept it as the whole story.

JR

[Updated on: Sun, 18 May 2008 09:22]

You guys are taking this way to seriously. I just wanted to report a case failure. I didnt want it to come off as "EWI cases are shit, dont use them." I will continue to support EWI products. As I have repeated many timess, I wasnt there when the damage occurred, so I dont know just how hard the case was hit.

Vince Byrne wrote on Sat, 17 May 2008 18:54

Mark invested both time and money he didn't have to into investigating your situation and went beyond the call to satisfy your concerns on a piece you bought second-hand with no knowledge of it's history, that's really the story here. Peace, Vince

Vince, I bought the case brand new in July 07. I found the purchase info on it the other day.


Now, lets all get off of each other's asses and go back to life... This thread is getting way to long for no reason...



Evan

[Updated on: Sat, 17 May 2008 19:09]

John Roberts {JR} wrote on Sat, 17 May 2008 15:00

So the equivalent static weight is a rough guess or a range, but if deceleration is rapid, 500#-1000# or more sounds plausible. Somebody who knows this stuff should check my work, it's been decades since I cracked a physics book.

I believe your 500# - 1000# estimate of a range of deceleration force of an average person jumping off a 1 meter height is a good estimation.

The generation of my approx. 480lb. deceleration "G" test of my 210lb. mass from 30" was fairly simply derrived. I have access to an old-style mechanical platform scale and the determination process was this:

1) I set the weights on the scale to an approx. value: 420lbs. (2X my body weight) to start with.

2) Jumped off the 30" step ladder and onto the scale... noticed the weight scale arm jumped right up (obviously too light of a setting).

3) Increased the weight setting on the scale to 500 lbs.

4) Jumped off the 30" step ladder and onto the scale... noticed the weight scale arm didn't much move.

5) Adjusted weight scale to 450... repeat jump & observation of weight scale arm. Too light.

6) Repeated the process till I found the 480 lb. setting on the scale was about "right" for what I'd consider to be a typical manner to break your landing after jumping off a 30" height. At the 480 lb. setting on the platform scale I observed a nice gentle nudge of the weight scale arm (didn't peg the needle, and the needle didn't stay in the mud) with me landing on the platform in a style that afforded about the same give in my feet and knees as I would if I was jumping off a 30" high stage and expecting to land on the ground.

I repeated the experiment landing harder (straight kneed and flat footed) and I could push the scale up to approx. 800 lbs. from the 30" height. I suspect that if I landed on the scale like a 210 lb. hunk of concrete falling off a truck... I could have pushed the scale quite a bit higher... but my knees aren't up to that.

A couple of years ago (for my 50th birthday) I experienced something new: I fell through the ceiling of my shop. I only dropped 10ft. to the ground... but the result of the body in motion (me) meeting with an immovable object (the concrete shop floor) was 4 broken ribs, two broken arm bones, a messed up rotator socket, and a shattered elbow. Judging by what I now know to be the crush strength that an MO24 case can withstand, I'd suggest that if the case hadn't given-way in the manner it did... if that was a human body (like mine) that inflicted that damage on that case... it's maybe a good thing that the case failed.

Goodness... maybe there's a marketing angle here... I can see it now: "MO24 mic case: Constructed in such a manner to afford failure of the case before your bones do." Wadda ya think? It could work?

[Updated on: Sat, 17 May 2008 21:12]