18 vs. 30 inch radius

[dominic c]

78Brougham

Hi all, I'm creating a HO layout around my living room on a shelf that I'm installing about 12 inches from the ceiling. I want to run my Amtrak train but i just can't wrap my head around how big I need to make the corners. I know the 18inch radius tracks are too tight for my Amtrak. How would you compute the 30 inch radius that I need? Or would I need more radius? How far from the wall corner would I need to put my 45 degree shelf? Please help! Thanks Kenny

 

Believe it or not, there's an app for that. Just plug in radius

Joe C

[CTValleyRR]

78Brougham

Thanks again for all the advice..I got it up and running and it looks great. Now.. time to put more back drop and scenery in and maybe get a dcc to utilize the sound my engine has.. sounds confusing to me I'll have do some research and talk with you guys some more.

DCC is really more appropriate for running multiple locos on the same tracks without fancy wiring blocks.  There are other solutions out there which enable you to take advantage of (most of) the functions of your sound decoder at a much lower price point than full scale DCC.

[riogrande5761]

What curve radii did you go with - title of this topic.  Don't keep us all in suspense.

[78Brougham]

Thanks again for all the advice..I got it up and running and it looks great. Now.. time to put more back drop and scenery in and maybe get a dcc to utilize the sound my engine has.. sounds confusing to me I'll have do some research and talk with you guys some more.

I put the train up there because it was just laying in boxes in the attic collecting dust and it was a shame not to be using it. We don't have any kids at home so it's not an issue about any youngsters seeing it, and lastly we've taken a number of trips on Amtrak and loved it!  So we figured why not do something with our Amtrak set that we can see every day. Hopefully one day I'll get a huge layout in one of the spare bedrooms. But for now this one's great

[hornblower]

I tried an around the ceiling layout once but took it down after it became apparent that all it was good for was running trains around and around.  I also discovered that the HO scale trains were somewhat difficult to see from a seated position and the kids were turned off to the whole thing after an hour or so. Since I wanted a layout that could support at least a little bit of operations, I quickly found that the around the ceiling location simply did not work.  I next tried a suspended layout but that presented a whole new set of problems that were equally as frustrating.  I now have an around the walls double deck layout in my garage.  There simply is no substitute for adequate layout space!

[bogp40]

Doughless

I support RioGrandes suggestion.  Use 30-ish radius sectional track.  No need for flex track since prototypical appearence of track is a moot issue at twelve inches from the ceiling.

I assume the footprint of the ceiling is the same as the floor, so just lay it out on the floor to get the size of 45 degree wedgie you'll need.  I would keep the track at least 2 inches from the walls too.

Of course, the size of the needed wedgie will depend upon how close to the shelves edges you want the track.

 

Also agree, and after corner sections are sized and track centers found, you can cut the "arc" to match the straight shelf width. This will be @ at least 6' 10" off the floor for door clearance, so the track should be somewhat close to the front edge anyway. Clear acrylic guardrail strips can be used as a derailment could be quite a long drop to the floor.

[78Brougham]

Thanks for all your advice guys! I'm going to sift through all these posts and try to see which one works best! Thanks to all for the ideas and advice !

[Doughless]

I support RioGrandes suggestion.  Use 30-ish radius sectional track.  No need for flex track since prototypical appearence of track is a moot issue at twelve inches from the ceiling.

I assume the footprint of the ceiling is the same as the floor, so just lay it out on the floor to get the size of 45 degree wedgie you'll need.  I would keep the track at least 2 inches from the walls too.

Of course, the size of the needed wedgie will depend upon how close to the shelves edges you want the track.

[rrinker]

 Yardstick used to be the cheapest way - because they used to give them out free at hardware stores. We used to always 4 or 5 of them around the house, so drilling a pivot hole and some radius holes in one didn't make anyone mad.

 But the large carboard template is probably the way to go - then you can position it in the corner on the floor and see how far the shelf will have to extend to support the track in the corners.

                --Randy

[Phoebe Vet]

You can buy or construct a trammel if you like.  I use a piece of light chain.  I don't recommend string because it can stretch.  I put a pin through a link at one end and the end of a pencil through a link at the other end.  You can make the chain any length that you need.  You don't need to cut it.

[jjdamnit]

Hello,

I did something in between.

I took a wooden yardstick- -available at your local home improvement center. Notched the center of the “0” end to accept a pin, nail or dowel.

I drilled holes at the correspoinding distances for radii of track, along the center line of the stick. Then scribed the required arcs on the roadbed.

Now, you not only have a variable radii tool, you also have a 3-foot straight-edge to connect the curved sections- -too boot!

I’s more rigid that the string method and more flexible than making a single trammel. And, it’s cheap!

Typically less than a dollar for the yardstick!

Hope this helps.

[ndbprr]

Since you will only be making four curves do it the easy way. Get a flat piece of cardboard like a big screen tv box and put a nail or pin in the edge. Tie a piece of string to it and tie a pencil on the other end 30" from the pin and draw an arc
Cut it with a utility knife and use a magic marker along the edge to position your curve.

[riogrande5761]

You can actually buy sectional track on a roadbed base by getting KATO uni-track.  It is code 83 and it comes in a nice range of curve radii including:

21 5/8"
24 "
26 3/8"
28 3/4"
31 1/8"

Probably one of the bottom two would be best for full length passenger cars.  You would not need to use a trammel like a giant compass - just connect a quarter circle of track together and you can use it as a template to draw out and cut the subroadbed you are using to support it.  MB Kleins has KATO unitrack for decent prices, and I just noticed Walmart came up on the search too, so apparently they are carrying it in some locations too.

If you are feeling really frisky, you can do the giant compass (trammel) method that will allow you to lay flext track and fasten it down on the centerline you draw.

Cheers, Jim Fitch

[skagitrailbird]

For a layout where your Amtrak train would be visible from the outside of a curve, i would recommend 30" as the minimum radius. Since trains on your high altitude around the room will monkey be seen from inside the curves, a lower radius won't look too bad. For trouble free operation 26" or 28" radius should work. 

Good luck!

[Train Modeler]

Another quick way of doing it is to measure 30" from the corner out to each wall, put a small mark in pencil so that it can be erased near the intersection of the ceiling and wall.   So, now you have two marks on each wall 30" from the corner.   Now measure 30" from each of those marks toward a point where they intersect, that will be the center of your radius, put a small pencil mark there on your ceiling, one that can be easily erased--maybe just use a small piece of sticky note(easily removable) and mark on it.   With that center point you can now use a 30" or the above trammel to help you determine how the road bed might look.   Another quick way is to use geometry and so the center point will be about 42.4" from the corner.  And so the tangent part of the curve of a 30" radius track will be about 12.4" from the corner.

OH and BTW, this 30" measurement will likely yield about a 28" track radius since the 30" will be measuring the outside edge of the roadbed.  So, be sure and include what offset you want from track centerline to roadbed's edge.

Richard

[dknelson]

Make a trammel out of a long straight piece of wood.  From a pivot point, mark and then drill holes at one inch intervals starting at about 26 inches up to 3o or 36 inches, holes just the right size to hold a pencil.  You use that to create half circles the correct radius -- perhaps on large pieces of cardboard that you cut out wide enough to be your roadbed -- that are templates for testing.  Am I making myself clear here?  You might use them for cutting the wood or other material that your actual base would be made of. 

If your Amtrak cars are full scale length I'd try to go 26" radius or larger.  At that height you do not want any derailments whatever.

Dave Nelson

[78Brougham]

Hi all, I'm creating a HO layout around my living room on a shelf that I'm installing about 12 inches from the ceiling. I want to run my Amtrak train but i just can't wrap my head around how big I need to make the corners. I know the 18inch radius tracks are too tight for my Amtrak. How would you compute the 30 inch radius that I need? Or would I need more radius? How far from the wall corner would I need to put my 45 degree shelf? Please help! Thanks Kenny