/ ice screw attachment
Haven't see them. Just tie it off with a krab removed from one side of a draw, or use an "ice-scream" screamer.
Not really. The now rather old BD research found that tieing off screws that weren't fully in could lead to failure: http://www.needlesports.com/catalogue/content.aspx?con_id=095232e4-4caf-49ec-8495-9c9e00a633da I don't think anyone has since shown this to be wrong?
These metal widgets would stop that from happening, like with the Grivel speedys, but it's much better just to have the right length of screw. I've got two of the speedys - in real world situations the widget can easily freeze to the body of the screw and then the krab flies round trying to flick you in the face as you spin the screw home! Quite annoying.
Because the bit round the screw is a thin metal plate it is unlikely to weaken the screw.
What do you mean by this?
I don't think it really says that:
In the limited testing we have conducted with tie offs and various extensions clipped into the hanger, our data suggests that it is best to clip in directly to the hanger if the screw sticks out less than 5 cm. If the screw sticks out more than 5 centimeters, tie it off as you normally would.
In the few tests conducted with tie offs the average strength is near 2700 lbf/12 kN. The typical failure mode of tied off screws is that, after about 1500 lbf/6.7 kN, the screw flexes and bends causing the sling to slip to the head of the screw, resulting in high leverage. Failure is generally caused by the sling being cut by the edge of the hanger in the 2000 to 3500 pound (8.9 to 15.6 kN) range. For the majority of placements this strength range is enough to hold typical falls. However, with a high impact force rope and a high fall factor, failure of the tie off could result. The best option is to simply place a screw of the appropriate length and not have to worry about tie offs altogether.
(All emphases are mine.)
They pulled each placement to failure anyway, they were just reporting the forces at which failure occurred.
Try Russ at Troll UK,
If they do...let me know ;)
Many thanks for the info, Joe Brown's are on the task hopefully it will be a positive outcome, if so I will keep you posted.
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