# Rigi Duo setup



## riderdan (Jan 2, 2014)

Hi all,

Starting to plan for the next project after the mountains are done (hopefully this weekend, if the rain holds off).

Has anyone set up a LGB Rigi set using piano wire for the cables and the rope that comes with the Rigi just to move the cars (as opposed to holding them up)? This should eliminate most of the "sag" that occurs when the Rigi cars are suspended from the stretchy cable they come with. I'm afraid the sagging cable just look bad (IMO)

Here's what I'm thinking overall...









I've built a concrete block "post" inside my mountains which I'm going to fill with concrete for weight. I'll attach a metal wall made from 1/4" plate to it with bolts and use eye hooks to hold the piano wire to the wall. This wall will be incorporated into the building at the top of the mountain. I'll do the same thing at the bottom with a concrete block embedded in the ground under the bottom station.










I plan to put piano wire (or similar rigid wire) between the two buildings, with the Rigi cars suspended from it. The wire will be attached to eye bolts, so I can adjust the wire tension by moving the fastening nuts, tightening or loosening as needed. Then I'll use the Rigi pulleys, controlled by a micro controller, to haul the cars up and down.

Has anyone one done something similar to this who can share their experience/setup? Anyone want to comment on why this might/might not work?

Thanks,
D


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## chuck n (Jan 2, 2008)

I'd be tempted to think about a pulley and weights on one end. That way the tension on the wire will stay constant. That is how the big boys do it. This will permit the wire to expand and contract with temperature changes. Both ends anchored could cause damage if the temperature changes and it will sag in the heat of summer and be tight in winter. 

I don't have one, but physics is physics.

Chuck


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## riderdan (Jan 2, 2014)

chuck n said:


> I'd be tempted to think about a pulley and weights on one end. That way the tension on the wire will stay constant. That is how the big boys do it. This will permit the wire to expand and contract with temperature changes. Both ends anchored could cause damage if the temperature changes.
> 
> I don't have one, but physics is physics.
> 
> Chuck


Good point. The temp swings here are pretty extreme (100 degrees summer to winter). I'll look into that. Thanks!


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## chuck n (Jan 2, 2008)

The pulley and weights would work 24-7-365. If you have a wild temperature swing and aren't home it will make the adjustments.

Chuck


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## denray (Jan 5, 2008)

1/4" steel to support piano wire? ok , maybe a little over kill, use a spring to take care of expansion of the wire.
simplifies things.
Dennis


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## toddalin (Jan 4, 2008)

I use 80# fishing line and the sag is not too bad. I think it would be even better with 120#, or better yet, stainless steel leader line which can be much stronger with less sag.


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## riderdan (Jan 2, 2014)

denray said:


> 1/4" steel to support piano wire? ok , maybe a little over kill, use a spring to take care of expansion of the wire.
> simplifies things.
> Dennis


Yeah, but I'm a big believer in using what I've got on hand.  I took a sheet-metal class last semester and I have some odds and ends of steel left over from that. And what I have is some 20 gauge tin and some 1/4" bar stock


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