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baza 1308 posts |
Aug 29, 2003, 23:40
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I agree with Nigel. The major breakthrough, if it works, is Gordon`s idea of using the lever principle to `row` the stones across the landscape. If you can do that, with comparative ease and a far fewer workforce than other attempts, then that should be demonstrated first, but you`d have to do it with the 40 ton stone. The trilithon project is a far bigger task, with all of the details far from being worked out yet. While we`re working on the theory of erecting the stones, we should also be thinking about a basic demonstration of simply moving large stones over a distance. baz
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Steve Gray 931 posts |
Aug 30, 2003, 00:06
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> join the two together with logs each side of the stone using motise and tenon joints with an extended tenon. (like the legs of a refectory table) When the wedges are driven home it will grip the stone like a vice. Extended tenons with wedges have all the strain on the wedge holes and they can easily shear away under strain unless the tenons are left fairly long. Tapered mortices and wedged tenons (like a hammer head) would make a stronger job and then further wedges could be driven between the stone and the logs to tighten the whole thing up, but in general I like the principle. It would be stronger than using a rope lashing and may well solve the problem of slippage.
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Steve Gray 931 posts |
Aug 30, 2003, 00:22
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> So what's wrong with something along my previous idea, tying some logs along the stone and notching them? The notches would effectively hook onto the corner of the tower and the whole thing would pivot round until it fell cleanly. I like the principle, but the problem is how to fasten the logs to the stone. When the stone reaches the angle at which it would have slipped, it is going to try to slip along the logs. The only thing restraining it is friction. For the block not to slip along the logs the rope has to increase the contact force with the logs to a point that does no exceed limiting friction. For a coefficient of friction of 1 the binding would have to produce 40 tons of pressure between the block and its logs in order to support it at the vertical. I know we dont't need to go that far, but the coefficient is probably less than 1 and we may need to get to 80 degrees or so. Of course 40 turns of rope around the block would mean that the average strain on the rope would only be 1 ton. Do we know what kind of ropes were available at the time and how thick a 1 ton rope of that era would be? Actually the same argument applies to Gordon's suggestion of using wedged mortice and tenons. Would they be strong enough to increase the frictional force sufficiently?
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GordonP 474 posts |
Aug 30, 2003, 06:08
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Ah!!!! my Archilees heel. Hammer the wedges in to hard and the tenon shears along the grain of the wood. Solution, Insert a dowel through the tenon at a point midway between the wedge hole and the end of the tenon, This greatly increases the strength of the joint probably by a factor of ? (over to you Steve) The builders of Stonehenge would have been expert woodworkers, as carpentery must surely be the oldest profession of all.
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GordonP 474 posts |
Aug 30, 2003, 06:40
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>The major breakthough, if it works. It works fine, and unlike all other methods previously proposed the problem doesn't grow expotentially with the size of the stone. If four men can move a 4 ton stone, then forty men can move a 40 ton stone, as each man is able to move his share unemcumbered by his workmates. In fact four men were needed to move the 4 ton stone only because a minimum of four levers were needed to balance the stone. I intend to try six men on the 10 tonner and I fully expected it to work, If I end up with egg on my face we can all have a good laugh, then do it with twelve men, we'll still be miles in front of the pro's. In short we don't need to move 40 tons to demonstrate the method.
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nigelswift 8112 posts |
Aug 30, 2003, 08:24
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(Should we use descriptive titles for sub threads, as I’m finding it hard to refer back?) Am I right that Steve’s idea is to have a pivoting log fixed transversely across the underside of the stone, so whilst the stone rotates from horizontal to vertical the pivot log effectively rolls through 45%? If so, lots of questions occur to me, including some possible dangers to be considered: It’ll take a bit of computing because, as well as pivoting, the stone is following the curve of the log and moving through a small arc, which it wasn’t before. I guess physical positioning of the pivot log on the edge of the tower needs to be extremely accurate i.e. the computer model may predict it’ll end up vertical but if it’s physically placed 4% off from the edge of the tower that’ll translate into the stone ending up 4% off vertical, maybe more. Also, what form is the edge of the tower? Is it square or is it another log? If the latter, can we place the stone pivot log exactly on top of the tower pivot log, along their whole lengths and will the one effectively roll round the other, uniformly?
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FourWinds 10943 posts |
Aug 30, 2003, 08:41
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U-Know the establishment won't like this at all :-) They will find any excuse to poo-poo it. They will do this without doing any 'maths of scale'. If you just do a 4 tonner then they will SHOUT VERY LOUDLY that that's only 4 tons, it would never work on a 40 tonner. Once a big name shouts that you'll have a real struggle to be heard ...
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FourWinds 10943 posts |
Aug 30, 2003, 08:45
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Surely you don't need to drop it in vertically. You just have to get it in the reagion of upright. Any straightening is done through packing stones later, no?
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nigelswift 8112 posts |
Aug 30, 2003, 09:11
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Exactly my thoughts FW. I can’t comment on whether Gordon can make a “collar” strong enough to fix a pivot log to the stone, but using his favourite assessment method – “does it feel right” I’m wondering if we’re ending up with two areas of risk, where we previously had only one (the strength of the edge of the tower). I know this is the opposite of my previous feeling that perfect pivoting produces perfect placement etc but I’m now thinking the practicalities may preclude it. Looking at the project in terms of risk analysis, and defining failure as “the stone ends up with an irrecoverably severe lean” I’m wondering whether if we dispense with the pivot log, and just tip the stone, slippage and all, we can avoid failure, as defined, whereas the existence of the pivot log could actually introduce the risk of failure. We’re focussing on an ideal, i.e. that the stone ends up plop, upright in the hole. Hence we’re trying to eliminate any element of variability by avoiding any element of slippage at all. However, maybe we should accept a degree of slippage and variability? We might allow for it perfectly and end up with an ideal result. But the point is, if we can’t be positive of that we can still proceed on the basis that any error won’t be of a disastrous scale. In other words, the worst result is that it’s in the hole but slightly skew and we can pull it straight? This contrasts with the situation where we had a collar and if it failed the stone could end up with an irrecoverable lean. In terms of authenticity I think this may be the right way to go, as well. I’ve looked at all the inside faces of the sarsen circle and confirm they’re all pretty smooth, certainly smooth enough that slippage would have been pretty predictable. (I haven’t checked this for all the trilithons though). So, whether deliberately or not, I think the ancients could have part pivoted and part slid them pretty predictably. Also, surely, they would have righted some of them by pulling on ropes? They wouldn’t have got them all perfect first time. And hauling stones upright was in their blood – most stone circles have crazily shaped stones that must have been dealt with that way. Gordon obviously wants to prove that only a small team was involved, but I think we can maintain that – the lean we’re anticipating will be small, so hopefully it would be easy. Maybe at that point his collar making skills could come into play – attaching a very tall log to the stone and attaching our ropes to the top of that?
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FourWinds 10943 posts |
Aug 30, 2003, 10:53
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Is it feasible to erect guide frames down either side of the hole? I'm just thinking that in the actual trilithon circle there's not much scope for the stone slipping sideways without hitting the stone next to it.
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