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Author Topic: Derrick Crane
Ken Hume
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Posts: 430
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Post Derrick Crane
on: October 24, 2013, 09:10
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Back in the year 2000 a practical demonstration was made at The Carpenters Fellowship first annual Frame meeting at Avoncroft Museum.

Henry Russell and John Winterbottom built and demonstrated the use of a simple derrick crane made from nothing more than two turned spruce poles, 2 pulleys, a steel pin, rope & a block & tackle.

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Lashings are used to make strong lifting and staying points

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The main gin pole is secured by guy ropes that are secured to nearby trees and ground anchors.

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This is a low cost lifting device that could be made in the woodland using suitably sized and inspected felled pole trees.

Ken Hume ET OWG

Ken Hume
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Posts: 430
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Post Re: Derrick Crane
on: July 28, 2015, 09:01
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The Weald & Downland Open Air Museum, Singleton, West Sussex erected and refurbished a timber derrick crane in the museum's wood yard in 2006.

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All of the timber parts were renewed using relatively young halved Douglas Fir which though strong does not have the same durability as European Larch. Douglas Fir has knot whorls that potentially can cause localised weakness whereas larch arranges its branches in a helix pattern thereby reducing the possibility of localised weakness.

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By 2015 following a detailed inspection of the crane it was found that the foot of one of the crane jib posts had rotted out within its metal cannister and so the crane was quickly dismantled to prevent any collapse of same.

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There is an interesting contrast between the two post bottoms in as much that one of these appears still to be in good condition. Given the rust patterns that exists on one of the cannisters it might be the case that the crane was not completely level resulting in rainwater running across the jib post bottoms and in one case then running betwen the post bottom and cannister and in the other to the open side of the cannister.

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Ken Hume

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