Building a small loop around the house?

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Dick_Morris
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Re: Building a small loop around the house?

Post by Dick_Morris »

What about making part or all of it removable? Instead of fill, for low spots trestles could be used, possibly as permanent parts of the sections of track. Flat bar is a lot more forgiving than aluminum for wide spacing of the trestles and ties. Shims can be used to do fine tuning.

A number of years ago we had a portable track that we set up about a dozen times in different places. It was a loop and a switch to a loading ramp. It had a lot of traffic using a heavy Mikado locomotive weighing around 800 to 1000 pounds which pulled a half a dozen cars full of people on maybe 100 loops per day. My recollection is that it used 3/8" x 1-1/2" flat HR bar stock. Joints were with a welded on tab that mated to the adjoining rail held together with 1/4" x 20 bolts. Ties were grooved 2" x 2". Since the surface was different in each place we used dunnage and shims to make it level. A weak points was the ties.
tomc
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Re: Building a small loop around the house?

Post by tomc »

rmac wrote: Tue Mar 09, 2021 11:35 am
tomc wrote: Tue Mar 09, 2021 9:35 am I think your Forney will need a large radius, probably 65" or greater
You probably meant 65 feet???
Yup I did. I guess I pressed the shift key when I shouldnt have!

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apm
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Re: Building a small loop around the house?

Post by apm »

Those are the ones I saw too.

The other key to this idea will be to figure out the minimum required turn radius as I have a few trees a shed and other issues to navigate around. Ideally I could rig up a large piece of flex track abs experiment with it to figure out how tight is too tight. Anyone have a good idea on how best to figure this out?
steamingon
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Re: Building a small loop around the house?

Post by steamingon »

Hello, RMI website gives the minimum radius for the Forney as 40' but 60' is recommended. Look here;

https://www.rmirailworks.com/Stuart.asp#.YFBhlNqSm1s
apm
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Re: Building a small loop around the house?

Post by apm »

steamingon wrote: Tue Mar 16, 2021 2:46 am Hello, RMI website gives the minimum radius for the Forney as 40' but 60' is recommended. Look here;

https://www.rmirailworks.com/Stuart.asp#.YFBhlNqSm1s
If you build the Forney per RMI's plans the trailing truck is a fixed pivot assembly and many people have had a lot of issues with getting them to make tight turn radius. I had been given a design by Jack Bodenmann I believe, for a floating trailing wheel assy. The whole thing not only pivots but floats laterally side to side with springs to center it. In early test runs I had some derailments on tight turns I loosened the nuts centering the springs and performance was far better. I would be curious to see what my engine can do. If RMI says 40ft min on their design I wonder if I could do better? On the other hand I know that locomotive always had a bad reputation for handling tight turns.

What's considered tight radius for a large 2-4-0 configuration or even a 2-6-0 or 2-8-0?
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milwiron
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Re: Building a small loop around the house?

Post by milwiron »

apm wrote: Tue Mar 16, 2021 5:17 pm In early test runs I had some derailments on tight turns I loosened the nuts centering the springs and performance was far better...
Do you know what the track radius and actual gauge numbers were when loosening the spring centering nuts helped with derailments? Unless the gauge can be opened up some I think you found your smallest radius limit.
Denny
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Glenn Brooks
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Re: Building a small loop around the house?

Post by Glenn Brooks »

One thing you could do with your Forney is pull the trucks off center as tight as they will go, then measure the wheel base from front wheel to rear. This gives you a minimum radius, e.g. chord length and height to center (measurement to drivers). You can use those two measurements to determine your tightest possible curvature. Radius from chord height is a very simple calculation. Plenty of internet calculators to help out.

Also use the same chord height process to lay out (or at least confirm) your curve radius when putting down track.

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Pontiacguy1
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Re: Building a small loop around the house?

Post by Pontiacguy1 »

That's a good estimate to start out with, but there are a few other things... Your locomotive should have some side-play in your drive wheels and your truck axles/axle boxes, and those will allow the locomotive to run through a tighter curve. Also, if you have thin flanges on some wheels or blind drivers on some axles, it will help out as well. I'm talking about locomotives with 3 or more driving axles with that. Widening the gage in curves will help out a lot too. If I plug in the rough measurements for my 2-10-0 into a chord calculator, it spits out about 65 ft min radius. However, the locomotive has been through a long 50' radius curve several times before, and even down approaching 45' radius long curves. It didn't like that one very much, but made it through without derailing.

There are some things that you can do to make your locomotive and track work better together to have tighter curves. The above calculator is a pretty good starting point, though.
thunderskunk
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Re: Building a small loop around the house?

Post by thunderskunk »

apm wrote:My wife's been asking me to build a small loop of 7.25" gauge track around the house...
You’re a genius. I dunno how you did it, but I’m impressed.
"We'll cross that bridge once we realize nobody ever built one."
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