Newbie with curve radius questions

Discussion in 'On30 Forum' started by obikonopa, Apr 3, 2006.

  1. obikonopa

    obikonopa New Member

    Hello all,:wave:

    I am new to model railroading and wanted to see if I could get some help on a few questions about curver radius... I own the Bachmann 2-8-0 Outside Frame Consolidation, I know that in the box it states the mininum curve radius to be 22 inches (I have read elsewhere that it can be as little as 18in.).

    What I would like to know is:
    1) when figuring the radius is it from the "center point" of curve to the -inside rail? -centerlinde(CL)? or -outside rail?
    2) when Bachmann figured the minimum curver radius: does this mean the engine can take the curve at -low speed? medium speed? high speed?

    I am working on my track plan and it seems to me that a 22" radius is pretty darn big(a 22" radius circle would take up almost a half a sheet of 4X8 plywood) so, How do you reach the back of the curve? with a lift out section(I would like to avoid this if possible)? I have an 8.5' X 11.5' room, the layout will be approx. 11.5' X 3' (except where I have the curves), it will be "L" shaped, and be a continuous loop type as opposed to a point-point. I will also have a work bench in the same room in one corner so I can work on my trains and other things. I like the look of my layout but these curves just seem GI-NORMOUS to me. So the smaller I can make them and still have my train steam around them at a good speed the better, A good speed be important because right now my layout is mostly curved track - there are two curves of more than 180degrees and one a little more than 90degrees. Any and all help would be greatly appreciated. Regards, Obi
  2. pgandw

    pgandw Active Member

    Radius in all except O 3 rail is measured to the track center. This means you need at least a 4ft width to swing 22 inch radius curves - leaves 2 inches to the edge for overhang, half of track and roadbed, etc. It does NOT leave much room to prevent your prize from seeking the lowest point of equilibrium available (the floor) in the event of a derailment.

    I do not own the engine in question, but I do know it is a fairly accurate O scale (1/48) model of a large narrow gauge prototype, regauged to run on On30 instead of On3. That it runs well on 22" radius is pretty good engineering. Usually, a manufacturer-listed minimum radius can be used - with good track work - at any reasonable SCALE speed. That particular prototype would strugge to do more than 50 MPH, which equals 1.5 feet/second in O scale.

    If you need to use 18" radius to stay within your space, you are generally going to be limited to the smaller On30 engines. Most of the 2-8-2s I have seen advertised require 22" radius. The outside frame was used on the prototype to get a bigger engine (bigger firebox) in a narrow gauge outline. Whether and how well your 2-8-0 will run on 18" radius, and what if any modifications are required, is a matter of experimentation. I suggest building a test track with 18" radius Snap Track. Run it at slow speed, and see what happens. Remove interfering details as necessary.

    Hope this helps
  3. Triplex

    Triplex Active Member

    Center of curve to centerline.
    You should expect this. An HO standard gauge 2-8-0 would run fine on 18". The On30 engine will be rather larger. In HO, you cannot have a circle accessible from only one side. The same will apply to On30.
  4. jetrock

    jetrock Member

    Putting an L-shaped loop plan in a room that small will be a challenge. The only way to reach the back of the layout will be to put in some trapdoors in the middle, so you can climb underneath and pop out of the hole to reach things.

    Have you considered running the layout around the walls of the room? A shelf layout a foot or two thick would allow for nice broad curves, and wouldn't dominate the room the same way that an L-shaped layout plan would.
  5. obikonopa

    obikonopa New Member

    Thank You jetrock, triplex & pgandw

    I appreciate the help and input.... The room in question is a "friggebod" which in english translates to a small house in the garden. I'm not worried much about the layout taking up TOO much room since this will eventually be my work/play house(it's a storage unit right now:) ). It looks like the "trapdoor" idea will have to be taken into consideration, because of the size limitations.

    I do have another question about the layout though. I have some left-over styrefoam(sp?) which is 4 inches thick and comes in sheets 2' X 4', the best way to describe it is: it is a white styrefoam which I believe is used in the U.S. on houses that have a "stucko" appearance. They attach the styrefoam to the house then "parge" with cement (I hope that helps to understand what I am talking about).
    Anyway, I wanted to know if this material is suitable to use on top of my layout table to build up mountains, etc... (I am going for a logging, mountain type layout), it is pretty stable, a person can stand(styrefoam laid flat) on it and it will only leave a small imprint of your shoe, not very deep. I plan to stack it on top of each other to the desired height (gluing it) then shape it. Can I place the track directly on this styrefoam? or should I place thin plywood on top of the styrefoam where the track will be placed?
    Thanks again for any help. Regards, Obi
  6. jetrock

    jetrock Member

    Many in the US do mount their track directly on styrofoam, or if they are using cork or foam roadbed, mount the roadbed using a product called "Liquid Nails" to glue the roadbed, then the track, to hold down the track. Long straight pins are used to hold the track in place while the glue is drying.

    The main hazard with using Styrofoam is that if it is the kind that is made up of little round balls, they will make a horrible mess when you cut the stuff up. If it is the blue or pink kind then it is very common for model railroad use. Many consider it important to put a thin layer of styrofoam underneath, or at least a wooden frame, but it's plenty strong by itself.

    Give some thought to an around-the-room shelf layout: it means putting a duck-under or an openable bridge in front of the door, but you'll have more usable space, wider curves without the "balloon" effect of a 4x8 style layout's curves, and easier access without having to install "mole holes" to hop around your layout.
  7. 60103

    60103 Pooh Bah

    Obi: The styrofoam sounds as if it may be OK. The white styrofoam that's used to pack stereo equipment is to be avoided. 4" thick (10 cm?) sounds awesome.
    To glue it you need a glue that won't dissolve the foam, but will stick it. I've been using a green contact cement. Do you have a glue that works in construction applications?
    You may be able to carve it into scenery shapes with a hot wore tool, although 4" is about the limit of the ones I've seen (commercially).
    Consider a layer of cork for roadbed -- about 6mm thick. You can glue this down and then pin or glue track to it.
  8. obikonopa

    obikonopa New Member

    Thank You again folks,
    60103, way to go on the metric conversions:) . Why is the white(made up of small round balls) styrofoam to be avoided? because of the mess? I hope it is only the mess, because that's the kind I have but with a more "density" to it. The mess doesn't so much bother me because it was FREE, given to me from left-overs on a construction site. Free is good when on a budget.
    Jetrock, I've been considering your shelf idea a little more and I'm beginning to come up with an idea.... What do think of a "shelf-like" triangle or another way to look at it would be a three sided layout with a big hole in the middle? Your shelf idea has some possibilities, making it so the controls are in the middle with the track going around the outside, it's then accessible to all the corners unlike a big 4X8 type "L" layout and I can still build each side 2.5 feet deep to give me more "landscape" for the logging/mountain look. And a big plus is that I still have one-half of the room left(the other triangle) to build my work bench. I'm beginning to see the light at the end of the tunnel:) . I like your idea the more I think about it. I believe I will start doing some drawings on this new idea tomorrow.
    Thanks again all. Regards, Obi
  9. webmaster

    webmaster Member

    Allot of people will tell you to stay away from 'the white stuff'. I think it is because it is messy, however, I use the white stuff & have done for years. I shape it with a fret saw and P80 wet 'n' dry paper (the paper that's used on automobile bodies) and then cover it with Mod-rock (Plaster coated bandage). Yes it does make a mess, but as long as you have a half decent vacuum cleaner it's not a problem. Best of all is that most of the time you can get it free when it comes as packaging.
  10. jetrock

    jetrock Member

    I have used "the white stuff" plenty, on my own layout and a display layout. It works fine structurally, but the mess...well, put it this way, I last used the stuff in quantity a year or so ago and I still stumble across bits of styrofoam in the corners of the layout room.

    The 4" thick insulation kind is nice for making big vertical hills--fewer sandwiched layers. My first project using it was a 2x2x2 cube that I had to fill as much as possible vertically.

    obikonopa: One thing to keep in mind is that a shelf layout need not crowd out a workbench. My workbench sits directly underneath part of my layout: that portion is only 1' deep. The layout is built at about 50" off the ground, the work bench is 30" high, which gives me about 18" for cabinets and stuff that fits under the layout but can be moved easily if I need to get underneath. Some of the layout can be thicker for added depth--but when modeling a mountain scene, the vertical aspect is as important as horizontal depth. 30" is a good maximum depth, although it's still pretty deep--if you're doing mountain scenery it's not as bad as flatter terrain because you don't have to reach behind the foreground as much as reach over it--just watch out that your belt buckle isn't creating havoc in the foreground!

    The main problem with the hole in the middle is that your back will eventually curse you for installing a duck-under...unless you put a lift/swing gate in the hypotenuse.
  11. obikonopa

    obikonopa New Member

    OK everybody,

    Here is my next layout question. What sort of grade is the Bachmann 2-8-0 Outside Frame On30 "comfortable" climbing? I have read that the Bachmann Shay & Climax climb like a goat but don't recall seeing anything about the 2-8-0. I am sure that flatter is better but with a logging/mountian layout, I doubt that will be possible.
    Also, does anyone have an educated quess as to the climbing capability of the up-coming Bachmann 2-4-4 Forney On30? I know it will not be released for quite a while but I really like the Forney Steam Engine and will eventually get one(which will probably be my second and last Steam Engine). I would rather not build a layout and then find out afterwards that the Forney can't climb the grades.:cry:

    I really like the Bachmann products and their price. The 2-8-0 OF Consolidation is a great looking Engine and the up-coming Forney looks to be another beauty. Plus I really just like the look of the 2-4-4. I think the two of them will fit well together on my "small-ish" layout.

    Jetrock, as soon as I am done with my layout "sketch" I will try and figure out how to post them on here so you can take a look. I have a couple of ideas rolling around in the ol' noodle.
    Thanks again everybody, very kind of you to assist. Regards, Chris
  12. fsm1000

    fsm1000 Member

    On my website
    I show a porter doing a 10 inch curve and a shay doing 12.
    Also I show how to glue extruded foam to wood or foam with white glue. [there is a technique].
    Also the white foam is not as structurally strong or stable as the extruded stuff.
    It would be ok for some scenery that does not need to hold weight, but for track laying etc, extruded is best.

    I measure the radius from the inner rail. But 99% of others measure it from the center of the rails.

    Making a model of your model [as I show how on my site] is one of the ways to avoid problems I have found.

    I hope this stuff helps you out. :)

    PS> I don't sell anything on my website.

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