Wire broke on several frames

[JohnMcafee]

Oops!

Sorry Mrs M.

[IFGL]

are we sure this newton character was real, I mean if you believe in Santa then reindeer can fly.........

[Uncle Sumo]

Ah. I`m beginning to see the light. Thank you, Robo and David. Vectors, tensile strength, etc.. The crane thing seems to me to be a different thing - distance x load = moment - which is rotational.

[prospero]

Got hold of a little spring scale this morning.

Weighed a frame I just finished. 3.5kg. Strung the scale across the back as tight as possible without applying tension on the scale. Held up in the middle with one finger. 9.6kg. Holding it in two places also produced the same result. Slackened off the wire so that the hanging point was at the top of the frame. 3.5kg.


More tests later.......

[Roboframer]

They've already been done - all this is like the typical "I've had this print opposite my window for 15 years and it's not faded"

[prospero]

I do have had a print opposite a window for 15 years....etc.

Never had a wire break either.

There was a very interesting doco on the box a while back about the building of the Brooklyn Bridge. The man who designed it, a Mr.John A. Roebling also ran a steel company and made wire cable. He wasn't allowed to supply the wire for the bridge for some strange political reason and the cntract was awarded to a competitor. The competitor was a bit of a cowboy by all accounts and although each coil of wire went though a rigorous testing procedure, he managed to slip in tons of carp cable by swithing the inspection tags. By the time this came to light there had been miles of the carp stuff spun into the main cables. Removing it would have been a massive task. But Roebling had calculated the strain on the cables and specified them to take six times this figure. So as it turned out, even with the carp stuff they were still well within limits.

Can't beat a bit of over-engineering.



Then there is Shock Loading.

[IFGL]

I don't tie the cord loose because of fear of the cord breaking but because it would be pulling sideways on the wood frame this is where it is weakest.

[Gwickstrom]

Well it was the wire. It was defective. We had it replaced and no problems since..

[IFGL]

I had some picture cord break this week, it's the first time in 17 years this has happened, mind you it was holding my son's gigantic trampoline down, we have had some really high winds.