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hi everyone, a friend asked me to build a drawbridge for a train display. so this is what i came up with: (URL) is loosely based on the Hawthorne Bridge in Portland Oregon: (URL) are 3 spans. each span is 96 studs long. the center section lift is (...) (21 years ago, 28-Apr-03, to lugnet.technic, lugnet.trains) !
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| | Re: drawbridge
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(...) (21 years ago, 28-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) or did you work from memory or? Did you have any challenges in keeping the two motors sychronized? That's been a bugaboo for others, that one side or the other raises a bit too fast and skews things. I think this is my fave shot: (URL) thanks (...) (21 years ago, 28-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) yes thank you for fixing the link. some how some extra characters got added in to the link. i will be showing this at a talent show on may 10th. i just finished it yesterday. it was such a nice day outside and i don't really have a flat (...) (21 years ago, 28-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) Regarding the bridge: How do you disconnect the rail when it's time to raise the bridge? That was a very odd way to raise it BTW, I've never seen that before (but then again I don't have a fetich towards bridges as of yet). And you have waaay (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) And they still get added. I think there are something faulty with the configuration of your news reader. It seems to add a lot of HTML or other code to translate some carachters. Best regards, /Tobbe (URL) SPAM when e-mailing) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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Very nice. We had a lift bridge in our last display as well, but it couldn't run very many times before the crawlers would de-synch. This is the best pictures of our new ones that I have: (URL) like it because it looks like Ross Neal is pushing the (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) I hope my bridge design spreadsheet worked okay for you. Your trusses look good! Nice work. Very nice! (...) I've hit a similar problem in planning out a crane. I've contemplated using two separate winches to lift the main hoist, but just like (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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I just got through purchasing 4 rotation sensors for that very reason for my lift bridge ((URL) - in Creations). I will be adding the 4 rotation sensors and an additional rcx to my bridge sometime this year. Out of 32 motors, I could never get 2 (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) That is a nice bridge, but I was chiming in to comment on syncronization... Has anyone tried using a single motor, and putting the motor in the span? I know it isn't prototypical, but if the motor was in the span, and the string/chain was (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) In my view one of the simpler ways is to shaft connect the two motors if you can... You can hide it if you have the sort of lift bridge that has an upper connection between the two towers. It may not always work though. (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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In lugnet.technic, Christopher Masi writes: <snip> (...) The GMLTC tried that on our previous layout. We had a motor mounted in the span, geared down to technic 8-tooth gears on each corner. The gears would engage this piece: (URL) (1x20 gear rack) (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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Chain: been there done that, it wasn't a pretty sight... Lego chain is not strong enough for the weight and forces a lifting mechnism will put on it. I tried chain on my lift bridge before eventually moving on the string. I bought over $120 worth of (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) Thanks for the tip, I guess we'll cross that off our "to try" list! JohnG, GMLTC (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) the rails on the lift span are not connected to the rest of the rails. there is a separate power connector run to the rails on the lift span. since the rails are not connected, there slopes on the sides to help keep the rails aligned when the (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) your spreadsheet is awesome. it worked great for calculating the length and heights. the only small problem was that the diagonal braces on my bridge all go in one direction, which your spreadsheet does not model. so your spreadsheet could (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) i'm using eudora to read and send to the news group. that is probably what my problem is. ¤º°`°º¤ø,¸¸,ø¤º°`°º¤...¤øø¤º°`°º¤ Bob Kojima ko@fial.com (URL) Incorporated Telecom Monitoring Solutions 4343 SW Corbett Ave Portland, OR 97201 (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) Ok, here's my idea for a solution for a vertically lifting bridge. All you need is one winch connected to one lifting line. You also need one control line(running off the same motor but geared down 2:1). The lifting line goes up the first (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) I don't follow. It appears your diagonals go in both directions, mirrored about the center of the bridge: (URL) did you mean that your diagonals go from top right to bottom left (looking at the right-half of a span), and the diags on my (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) my description was not that good. here is how the diagonals are on my bridge: / | \ | \ | \ | \ | / | / | / | / | \ and the diagonals in the spreadsheet: / | \ | / | \ | / | \ | / | \ | / | \ (hope my ascii art turns out ok) so only 2 of the (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) I've thought of a simpler way of describing my system. Basically you have a rope stretched between two towers. If you pull the rope the span goes up, release it and the span goes down. The wire is connected to the lift span at both ends via (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) the length of the wire has nothing to do with the speed. the problem is that one motor, the first one on the line, is getting most of the power. the motor at 9v, 12v or 115v that doesn't mean thats the exact amount of power that it uses, it (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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That might very well almost hold true (I am no expert) if your motors were hooked up like: [power]--------[moto...---[motor] (parallel circuit) But I have mine hooked up like: [motor]--------[powe...---[motor] (parallel circuits) I assume one motor (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) well since i was basing my theory of working with stereos and lights on my car, you have the uperhand...lol (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) Yes, roger that. I get it :-) I can easily write a sheet to do that. Actually, I have one! But it's geared towards an arched bridge with suspended deck. I'll get these sheets to the public soon! -TJ (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) I believe your are right Steven, if two identical motors were connected in an identical way they would run at the same speed provided they had identical loads. But nothing in this physical world is identical and that is why stepper motors and (...) (21 years ago, 29-Apr-03, to lugnet.technic, lugnet.trains)
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| | Vertical lift spans (was: Re: drawbridge
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Not sure where to chime in, so I'll jump in here. Regarding the lifting of vertical lift spans: I've built many of these over the years and my latest version (yet to be published on the internet) takes advantage of an engineering survey done on one (...) (21 years ago, 30-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: Vertical lift spans (was: Re: drawbridge
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(...) OK, this is similar, but first take a walk down to the local auto repair shop and see if you can look at a 'cats cradle' type auto hoist. Here is my description. It involves one string to lift one end of the span and another string, which is (...) (21 years ago, 30-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) I used a single motor, with all cables being passed above the top of the span to get to the far side (4 cables). One trick that I would do if I was building another one is to make the cable drums easier to adjust to one another, since they (...) (21 years ago, 30-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: Vertical lift spans (was: Re: drawbridge
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Well put Ben. I have seen Ben's steel bridge (and helped re-rig the cables to the pulleys after a minor anomaly), and I can attest that it is truely one of the finest LEGO bridges in the AFOL community, or in the world for that matter. It is very (...) (21 years ago, 30-Apr-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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"James Powell" <wx732@freenet.victoria.bc.ca> wrote in message news:HE4yp6.15uI@lugnet.com... (...) span (...) building (...) since (...) (rope (...) Just a thought when reading this thread: If you have trouble with motors that do not run with the (...) (21 years ago, 1-May-03, to lugnet.technic, lugnet.trains)
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(...) I've just seen a bridge that instead of being lifted up is instead lowered under the water onto the river bed. That would be cool to see modelled. The hard part would be covering up the lowered bridge with fake water. I suppose a cover (...) (21 years ago, 4-May-03, to lugnet.technic, lugnet.trains)
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(...) Yep.=20 (...) Whoa, buddy, not just the links -- they're everywhere :)=20 (...) Does =20 mean anything?=20 (...) Oh well. That doesn't keep it from being a cool bridge :)=20 (...) Hi.=20 (...) What's ^this stuff supposed to mean?^=20 Matt (...) (21 years ago, 5-May-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) Those are non-ASCII characters. If your browser/newsreader displayed them correctly you would see a sort of wavy line. Since only characters between 32 and 126 are guaranteed to be printable on all screens and to pass through all kinds of (...) (21 years ago, 16-May-03, to lugnet.technic, lugnet.trains)
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| | Re: drawbridge
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(...) Our club's first lifting bridge (by David Wegmuller) took that approach. The trouble is that it screws up the entire layout because everything is off by 2 studs. For David's second version, he had to modify the ends of the track connectors so (...) (21 years ago, 16-May-03, to lugnet.technic, lugnet.trains)
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(...) True, but it's not hard to make up two studs on the first curve that you happen to get to. (or in this case, one each, if that's easier) So for the LEGO purist, this is a better approach. (21 years ago, 16-May-03, to lugnet.technic, lugnet.trains)
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