Cinch Buckle Slip and Stress Test (vid's)

[GT]

1500 lb poly webbing slip test.


3000 lb poly webbing slip test.


Cinch Buckle stress test to complete failure.

[GrizzlyAdams]

thanks for doing this.
Trying to understand what the experiment did and the what the graph means...the tension rose to something over 1100 lbs, and then dropped to something near 650 lbs. I imagine the machine increasing the tension automatically, until it 'felt' the slip (or a break). And then what happens? How does it get to 650+ and why does it stay there?

fun toys!

[GT]

thanks for doing this.
Trying to understand what the experiment did and the what the graph means...the tension rose to something over 1100 lbs, and then dropped to something near 650 lbs. I imagine the machine increasing the tension automatically, until it 'felt' the slip (or a break). And then what happens? How does it get to 650+ and why does it stay there?

fun toys!

Hi Grizz, It broke it's hold at around 1100 lbs then rapidly slipped down to 656 where it took 656 pounds to keep pulling it thru the buckle.
Yes! it is fun. Machine needs work though. Got to send the cylinder out for overhaul soon and the pneumatic/hydraulic power pack is acting up. Readings are still accurate though.

[GT]

After reviewing the video of the 1500lb webbing, I now think that the sudden drop from 1148 pounds down to 656 was due to webbing damage and not the buckle losing its grip. Just as the buckle cut thru the 3000 webbing it was cutting thru the 1500 the same way, but as less tension. Look and see how shredded it is at the end of the test.
The 350 pound safe working load still stands though since the damage didn't occur until 1148 pounds was reached.

[scryan]

thanks for doing this.
Trying to understand what the experiment did and the what the graph means...the tension rose to something over 1100 lbs, and then dropped to something near 650 lbs. I imagine the machine increasing the tension automatically, until it 'felt' the slip (or a break). And then what happens? How does it get to 650+ and why does it stay there?

fun toys!

Grizz, usually graphs like that are force vs displacement.
The bottom axis says "Stretch not recorded" but if the machine is set up like a normal tensile test that axis should have how far the machine pulled. Usually the machine is measuring the load on at as it continues to move...
So the machine pulls apart until a max load of 1100 is reached, then it would look like the strap pulls through, and can only transmit the 650 load.
It is not that the machine backs off... It doesn't pull with fixed force, the force recorded is simply the force that the sample is being subjected to, or the force the sample holds up to as the ends are pulled apart.

[gunner76]

That fun to watch. Always wanted to know how much that cinch buckle could take.

[GT]

Grizz, usually graphs like that are force vs displacement.
The bottom axis says "Stretch not recorded" but if the machine is set up like a normal tensile test that axis should have how far the machine pulled. Usually the machine is measuring the load on at as it continues to move...
So the machine pulls apart until a max load of 1100 is reached, then it would look like the strap pulls through, and can only transmit the 650 load.
It is not that the machine backs off... It doesn't pull with fixed force, the force recorded is simply the force that the sample is being subjected to, or the force the sample holds up to as the ends are pulled apart.

Right! The piston advances at the rate I make it advance. To follow the criteria set by the WSTA in must move forward at a rate of no less than 2" per minute.
The cylinder is a 10,000 pd cylinder and the pump the same. But it will only put out 10000 pounds if it needs to. If it only needs to push something along at 500lbs, it will only push at 500. Unless the 500 pound item runs into a block wall, then it will push at the pressure it needs to punch a hole in the block wall. Up to 10,000 pounds. Someday I hope to build another machine that will do 20,000 or 30,000.

[GT]

That fun to watch. Always wanted to know how much that cinch buckle could take.

The 1200lb rating I kept hearing was probably the "Safe Working Load" and I just thought it was the breaking strength.
A lot of companies will back off a couple hundred pounds on the actual Safe Working Load just to be safe.
I couldn't believe my eyes when I saw it go up over 4000 lbs. I've pulled a lot bigger hardware than that tiny little buckle that didn't make it anywhere near 4000 pounds.

[GT]

That fun to watch. Always wanted to know how much that cinch buckle could take.

LoL! I got grazed in the back of my head by one of the pieces. When something lets go at 4444 pounds, it's like a bullet flying around the room. Funny thing is
my pump has enough hose on it for me to stand in the next room over but do you think I'm that smart? Nope!
I remember pulling a 2" piece of webbing last year until it failed and when it did it went off like a cable snapping. Filled the room with what looked like those little milk weed seeds floating around.
Having so much fun should be against the law.

[XTrekker]

Do you think you could test some 7/64 Amsteel and compare a proper tapered buried loop vs a buried loop with no taper. Would also like to know what some 2.2mm Dynaglide can really handle.

Man if I had one of those machines, i'd have every one of my whoopies and UCRs on that thing with every type of line I had..lol