question about designing layouts in HO

[Anonymous]

I have some experience with O scale and I am currently beginning to work with HO. The advice I have been given thus far strongly suggests making the curves as large as possible, preferably 22's or 24's. Doing so results in very large curves that are actually as large as or larger than what I used in O gauge. Is it really necessary to use such large curves in HO?? I realize that the train will run more smoothly with a larger curve, but will it really run that poorly if I use an 18 curve ?? Thanks for your help.

Mark

[Anonymous]

I have some experience with O scale and I am currently beginning to work with HO. The advice I have been given thus far strongly suggests making the curves as large as possible, preferably 22's or 24's. Doing so results in very large curves that are actually as large as or larger than what I used in O gauge. Is it really necessary to use such large curves in HO?? I realize that the train will run more smoothly with a larger curve, but will it really run that poorly if I use an 18 curve ?? Thanks for your help.

Mark

[Anonymous]

Well Mark, I have good news and I have some bad news; which would you like first.

The good news, 24 inches will work just fine for most engines and cars, but 30 inches works even better for articulated's and passenger cars - anything that is long.

When I was a newbie, I spent a fortune on a brass Royal Hudson, and took it home to run on my 4 by 8 layout. I didn't take minimum radius serioulsy then. After I discovered I couldn't run my Hudson, my philosophy changed.

[Anonymous]

Well Mark, I have good news and I have some bad news; which would you like first.

The good news, 24 inches will work just fine for most engines and cars, but 30 inches works even better for articulated's and passenger cars - anything that is long.

When I was a newbie, I spent a fortune on a brass Royal Hudson, and took it home to run on my 4 by 8 layout. I didn't take minimum radius serioulsy then. After I discovered I couldn't run my Hudson, my philosophy changed.

[Anonymous]

I model in N scale and consider 18" a workable minimum radius, at least for mainlines. On individual industry spurs, I might go down to 12". Translated to HO scale, this becomes 36" radius mainlines and 24" spurs; anything less than this, while it might run okay, just looks toy-like, no matter how deftly a scene is modeled. This is because of the sharp angle that is formed between cars as they traverse the curve; any prototype photo shows a much gentler condition.

In N-scale, I have had troubles even on 18" curves with really long and heavy trains, because the sharp curve gives the train a tendency to derail, since a straight line (called a "chord") is shorter than the distance along the circumference. The engines and the inertia of the train behind are playing tug-of-war, and all there is to resist it is the friction of the wheels on the rails. I don't know if this is a problem with HO scale, especially if all the cars are properly weighted (I'm currently adjusting weights in my freight car fleet, so hopefully it'll disappear in N-scale), but it definitely is more pronounced on tighter curves.

If you need to use 24" (or less) curves to fit your space, try to hide as much of that curve from view as possible. Make sure it remains accessible, because it may be a derailment problem area, and treat yourself to a nice broad curve somewhere up front and center. John Allen called this a cosmetic curve, and you'll love posing your trains on it... go for 60" radius or more.

I am an architect, and I have no problems finding ways to get generous curves into tight spaces.

[Anonymous]

I model in N scale and consider 18" a workable minimum radius, at least for mainlines. On individual industry spurs, I might go down to 12". Translated to HO scale, this becomes 36" radius mainlines and 24" spurs; anything less than this, while it might run okay, just looks toy-like, no matter how deftly a scene is modeled. This is because of the sharp angle that is formed between cars as they traverse the curve; any prototype photo shows a much gentler condition.

In N-scale, I have had troubles even on 18" curves with really long and heavy trains, because the sharp curve gives the train a tendency to derail, since a straight line (called a "chord") is shorter than the distance along the circumference. The engines and the inertia of the train behind are playing tug-of-war, and all there is to resist it is the friction of the wheels on the rails. I don't know if this is a problem with HO scale, especially if all the cars are properly weighted (I'm currently adjusting weights in my freight car fleet, so hopefully it'll disappear in N-scale), but it definitely is more pronounced on tighter curves.

If you need to use 24" (or less) curves to fit your space, try to hide as much of that curve from view as possible. Make sure it remains accessible, because it may be a derailment problem area, and treat yourself to a nice broad curve somewhere up front and center. John Allen called this a cosmetic curve, and you'll love posing your trains on it... go for 60" radius or more.

I am an architect, and I have no problems finding ways to get generous curves into tight spaces.

[Anonymous]

Avondale,
I hope in your architecture you don't do anything to scale.... lol. 18 inches isn't 36 in HO. N scale is 54 % of HO so slightly over half. So 18 inches is....(got to go to my calculator - be right back).... 33.333 inches in HO.

And 12 inches is..... (back to calculator)..... 22.2222 in HO.

Actually I think N is 54.4 of HO scale, but I'm not sure.

[Anonymous]

Avondale,
I hope in your architecture you don't do anything to scale.... lol. 18 inches isn't 36 in HO. N scale is 54 % of HO so slightly over half. So 18 inches is....(got to go to my calculator - be right back).... 33.333 inches in HO.

And 12 inches is..... (back to calculator)..... 22.2222 in HO.

Actually I think N is 54.4 of HO scale, but I'm not sure.

[Anonymous]

I thank you for your responses and I have a few more questions. When you suggest that the curves should measure at least 24" or when you state that you really think they should be at least 60", are you talking about having at least one curve that size or do you really mean ALL the curves?? I am not trying to rehash what you said, it is just that if you really mean that all the curves should be at least 24", then most of the track pices made by Atlas, Walthers, Peco and the other track manufacturers are useless because very few of their curves are actually 24" or greater in size. It also means that the two books I have from Atlas with suggested HO layouts unusable because all the layouts in those books make significant usage of curves much smaller than 24". It also means that the curves in my HO layout would actually be larger than the curves I used in my O guage layout. Is this really the case? Are you really saying that in a 4 x 8 sheet of plywood, if I use nothing smaller than a 24" curve and don't form S's because they are neither safe nor prototypical, I can get little more than a simple oval? Is this really true for HO?? Thanks for bearing with me and helping me out.

Mark

[Anonymous]

I thank you for your responses and I have a few more questions. When you suggest that the curves should measure at least 24" or when you state that you really think they should be at least 60", are you talking about having at least one curve that size or do you really mean ALL the curves?? I am not trying to rehash what you said, it is just that if you really mean that all the curves should be at least 24", then most of the track pices made by Atlas, Walthers, Peco and the other track manufacturers are useless because very few of their curves are actually 24" or greater in size. It also means that the two books I have from Atlas with suggested HO layouts unusable because all the layouts in those books make significant usage of curves much smaller than 24". It also means that the curves in my HO layout would actually be larger than the curves I used in my O guage layout. Is this really the case? Are you really saying that in a 4 x 8 sheet of plywood, if I use nothing smaller than a 24" curve and don't form S's because they are neither safe nor prototypical, I can get little more than a simple oval? Is this really true for HO?? Thanks for bearing with me and helping me out.

Mark

[Anonymous]

Those curves work just fine with flex track. It sounds like you haven't used flex track, time to learn. For your main line at least, you want as big a curves that will give you an adequate (however you define it) layout. Remember radius isn't diameter, so 30 inch radius, 60 inch diameter.

In your initial post, you didn't say you were modelling on a 4 by 8, so on a layout that size you are probably going to have 18 inch radius. You just need to know that some engines won't take an 18 inch curve; plan your layout around engines that will, and rolling stock that will.

By the way, a 4 by 8 layout plan I really like with lots of action is called the Red Wing Division I believe and was in 1995 MR, but don't hold me to that year. Do a search for the Red wing Division layout (in the search area of trains.com for magazine articles) and check it out. I think you might like it.

[Anonymous]

Those curves work just fine with flex track. It sounds like you haven't used flex track, time to learn. For your main line at least, you want as big a curves that will give you an adequate (however you define it) layout. Remember radius isn't diameter, so 30 inch radius, 60 inch diameter.

In your initial post, you didn't say you were modelling on a 4 by 8, so on a layout that size you are probably going to have 18 inch radius. You just need to know that some engines won't take an 18 inch curve; plan your layout around engines that will, and rolling stock that will.

By the way, a 4 by 8 layout plan I really like with lots of action is called the Red Wing Division I believe and was in 1995 MR, but don't hold me to that year. Do a search for the Red wing Division layout (in the search area of trains.com for magazine articles) and check it out. I think you might like it.

[IRONROOSTER]

When talking about curves and layouts the radius is a minimum radius, use at least that and maybe more on the mainline, spurs can use less, but restrict equipment usage. On the NMRA'a site - www.nmra.org - there is a section called Standards and RPs. RP-11 shows recommendations of equipment for different curves in all scales. BTW O scale as opposed to O Hirail / tinplate (i.e Lionel) uses really large curves.
Enjoy
Paul

[IRONROOSTER]

When talking about curves and layouts the radius is a minimum radius, use at least that and maybe more on the mainline, spurs can use less, but restrict equipment usage. On the NMRA'a site - www.nmra.org - there is a section called Standards and RPs. RP-11 shows recommendations of equipment for different curves in all scales. BTW O scale as opposed to O Hirail / tinplate (i.e Lionel) uses really large curves.
Enjoy
Paul

[Anonymous]

Greetings

I just started back into the hobby and I am modelling HO Scale Union Pacific so that means big radius turns my minimum radius is 36" my biggest is leading into a spur is 60" I will not be running anything as stiff legged as a 9000 eventhough I still want one. Moslty bigboys challengers and northerns.
My layout is designed around my wifes car and over hangs the windshield.
Go as big as possible it looks better prototypically and will allow you to run anything larger if you want to.

Good luck

Sean

[Anonymous]

Greetings

I just started back into the hobby and I am modelling HO Scale Union Pacific so that means big radius turns my minimum radius is 36" my biggest is leading into a spur is 60" I will not be running anything as stiff legged as a 9000 eventhough I still want one. Moslty bigboys challengers and northerns.
My layout is designed around my wifes car and over hangs the windshield.
Go as big as possible it looks better prototypically and will allow you to run anything larger if you want to.

Good luck

Sean

[DSchmitt]

18" is historically the "standard" minimum radius for HO because it fits nicely on a 4' wide sheet of plywood and everything will be reachable if there is access from both sides. It is adequate for 4 axel diesels, small steam locos and 50' cars. Larger equipment may work ok, but appearance will suffer.

There are fewer compromises with scale accuracy on most of the HO equipment now available than there was in the past, (for instance when I started in HO truck mounted couplers were the norm) so a larger radius is required to operate properly.

O gauge and O scale 3-rail usually has truck mounted couplers and can negotiate tight curves. O scale 2-rail with body mounted couplers requires much larger radius than HO for proper operation and appearance..

[DSchmitt]

18" is historically the "standard" minimum radius for HO because it fits nicely on a 4' wide sheet of plywood and everything will be reachable if there is access from both sides. It is adequate for 4 axel diesels, small steam locos and 50' cars. Larger equipment may work ok, but appearance will suffer.

There are fewer compromises with scale accuracy on most of the HO equipment now available than there was in the past, (for instance when I started in HO truck mounted couplers were the norm) so a larger radius is required to operate properly.

O gauge and O scale 3-rail usually has truck mounted couplers and can negotiate tight curves. O scale 2-rail with body mounted couplers requires much larger radius than HO for proper operation and appearance..

[Anonymous]

Mark:

Following up on the posts above, the minimum radius you want will depend largely on what era you are modeling and thus what size motive power and rollingstock you want to run.

Early in the last century most freight cars were in the 36-40 foot class, most motive power of the four or six coupled variety, thus you can use smaller radius curves. Late in the steam era motive power became much larger as did passenger car lengths, thus you will require larger curves.

Also there is the issue of "look". Most larger rollingstock will actually operate on smaller radius curves but will "look" out of scale and pinched due to overhang.

My advice to you is to follow the MNRA standards closely, you will have less operational trouble and be happier with your layout appearance.

Good Luck

Randy

[Anonymous]

Mark:

Following up on the posts above, the minimum radius you want will depend largely on what era you are modeling and thus what size motive power and rollingstock you want to run.

Early in the last century most freight cars were in the 36-40 foot class, most motive power of the four or six coupled variety, thus you can use smaller radius curves. Late in the steam era motive power became much larger as did passenger car lengths, thus you will require larger curves.

Also there is the issue of "look". Most larger rollingstock will actually operate on smaller radius curves but will "look" out of scale and pinched due to overhang.

My advice to you is to follow the MNRA standards closely, you will have less operational trouble and be happier with your layout appearance.

Good Luck

Randy

[Anonymous]

Maybe this will help you to understand what they are telling you.

As has become our tradition, I put a circle of track around the Christmas Tree, using 18" radius curves and an RSD-5 locomotive. This year I decided to institute passenger sedrvice using an 80 foot coach.

My daughter immediately ask if real coaches were that long, whem I answered yse, she informed me that it did not like like it should go around thoses curves.

Yes. it did go around the curve, but it did not look correct,

Tom Blair

[Anonymous]

Maybe this will help you to understand what they are telling you.

As has become our tradition, I put a circle of track around the Christmas Tree, using 18" radius curves and an RSD-5 locomotive. This year I decided to institute passenger sedrvice using an 80 foot coach.

My daughter immediately ask if real coaches were that long, whem I answered yse, she informed me that it did not like like it should go around thoses curves.

Yes. it did go around the curve, but it did not look correct,

Tom Blair

[Anonymous]

It's also helpful when actually making the curve to use a trammel - a sort of compass. If you have ever seen the devices that cut large circular holes, they consist of a pivot point, a connecting piece, such as a piece of 1 X 1 stock, and a marker or cutter.

A yardstick works just fine, clamp a nail or a screw to the yardstick, then put your marker at the desired radius (distance from the pivot). You will come up with wonderfully smooth curves that will mark the center of your track. This is the technique I used on my very first HO layout and I've never regretted it. The curves were much more forgiving than using sectional track and while not all of my locomotives would run on the 4 X 8, the majority did.

[Anonymous]

It's also helpful when actually making the curve to use a trammel - a sort of compass. If you have ever seen the devices that cut large circular holes, they consist of a pivot point, a connecting piece, such as a piece of 1 X 1 stock, and a marker or cutter.

A yardstick works just fine, clamp a nail or a screw to the yardstick, then put your marker at the desired radius (distance from the pivot). You will come up with wonderfully smooth curves that will mark the center of your track. This is the technique I used on my very first HO layout and I've never regretted it. The curves were much more forgiving than using sectional track and while not all of my locomotives would run on the 4 X 8, the majority did.

[Jetrock]

A lot depends on rolling stock. If you model articulated engines and 80-foot passenger cars, you want curves that are as broad as possible. If you model lightweight steam or four-axle diesels pulling 40-50 foot cars, you want some breadth but will do fine with 18-24" curves. If you model 0-4-0's and two-truck Shays pulling logging disconnects, you can go for ridiculously short curves and if you model traction, the curves can often be not much longer in radius than the length of the car.

Setting is also a factor--if you model the Great Plains, 15" curves are going to be hard to justify, while someone modeling snaky mountain roads or urban environments has an excuse for flange-scraping sharp curves.

Focus of scale is also important. N scale's forte is being able to model loooong trains in a small space, so that 18"+ curve looks nice--but HOn30 engines (mostly converted 0-4-0's) running on the same width of track but in a different scale, look fine on flextrack bent down to 6" radius. They also look fine on 18" curves.

The pre-made curves are typically used by novice modelers rather than by the more experienced--and novice modelers tend to prefer the sharp curves because they're making a 4x8 or something equally small. Flex track, which can be curved to the user's choice of sharpness, is preferred among those who have some skill but aren't yet willing to lay track by hand.

[Jetrock]

A lot depends on rolling stock. If you model articulated engines and 80-foot passenger cars, you want curves that are as broad as possible. If you model lightweight steam or four-axle diesels pulling 40-50 foot cars, you want some breadth but will do fine with 18-24" curves. If you model 0-4-0's and two-truck Shays pulling logging disconnects, you can go for ridiculously short curves and if you model traction, the curves can often be not much longer in radius than the length of the car.

Setting is also a factor--if you model the Great Plains, 15" curves are going to be hard to justify, while someone modeling snaky mountain roads or urban environments has an excuse for flange-scraping sharp curves.

Focus of scale is also important. N scale's forte is being able to model loooong trains in a small space, so that 18"+ curve looks nice--but HOn30 engines (mostly converted 0-4-0's) running on the same width of track but in a different scale, look fine on flextrack bent down to 6" radius. They also look fine on 18" curves.

The pre-made curves are typically used by novice modelers rather than by the more experienced--and novice modelers tend to prefer the sharp curves because they're making a 4x8 or something equally small. Flex track, which can be curved to the user's choice of sharpness, is preferred among those who have some skill but aren't yet willing to lay track by hand.

[Anonymous]

Hi Mark
[2c]
Let me throw my two cents in and try not to confuse you more. [%-)]

First, I understand you have an Atlas track plan you like to build. Atlas test all their track plans and they do work. They have the layout on a grid to show you what size it is.

Second, look at the top or side of the page the track plan is on. See that little train? It might be pulled by a steam locomotive on one side and a diesel on another side. Atlas suggest this is the size and type of equipment that will run on that particular layout.

The size of the minimum radius will dictate what type of equipment you can run on it. Any other radius on the layout can be larger but none can be smaller than the minimum.

If you want to use flex track instead of sectional track, the simplest way (but more expensive) is to layout the track plan with sectional track and replace it with flex track after you laydown the roadbed.
However, when you use flex track for a curve you will have to cut off the excess rail at some point. You can use an Atlas snap saw or a flush cutting Rail Nipper cutting tool (click on highlited words). I also recommend this BOOK.
ALWAYS WEAR SAFTY GLASSES WHEN USING CUTTING OR POWER TOOLS
You can find used sectional track cheap at model railroad shows or on eBay.

In the Atlas book it shows to use upholstery tacks to secure the cork roadbed and track nails to secure the track. That is the old way and it makes for very bumpy roadbed and you can bend or break rail ties if you pu***oo hard on the track nails. Many modelers are now recommending latex cualking to glue track and roadbed.

The questions I have for you is, how much room do you have? Are you building on a 4' x 8' sheet of plywood or foam? Do you already own HO scale rolling stock? If so, what is it?

F.Y.I.
I made my own radius templates out of poster board. I made a compas from a wooden yard stick by drilling holes in it to hold a nail at the pivot and a pencil at different radi. They are 2 1/2" wide (that is my track center spacing for curves) so each edge will help me mark my center line. But now I'm getting off the subject here.

You can e-mail me if you have any other questions.

[Anonymous]

Hi Mark
[2c]
Let me throw my two cents in and try not to confuse you more. [%-)]

First, I understand you have an Atlas track plan you like to build. Atlas test all their track plans and they do work. They have the layout on a grid to show you what size it is.

Second, look at the top or side of the page the track plan is on. See that little train? It might be pulled by a steam locomotive on one side and a diesel on another side. Atlas suggest this is the size and type of equipment that will run on that particular layout.

The size of the minimum radius will dictate what type of equipment you can run on it. Any other radius on the layout can be larger but none can be smaller than the minimum.

If you want to use flex track instead of sectional track, the simplest way (but more expensive) is to layout the track plan with sectional track and replace it with flex track after you laydown the roadbed.
However, when you use flex track for a curve you will have to cut off the excess rail at some point. You can use an Atlas snap saw or a flush cutting Rail Nipper cutting tool (click on highlited words). I also recommend this BOOK.
ALWAYS WEAR SAFTY GLASSES WHEN USING CUTTING OR POWER TOOLS
You can find used sectional track cheap at model railroad shows or on eBay.

In the Atlas book it shows to use upholstery tacks to secure the cork roadbed and track nails to secure the track. That is the old way and it makes for very bumpy roadbed and you can bend or break rail ties if you pu***oo hard on the track nails. Many modelers are now recommending latex cualking to glue track and roadbed.

The questions I have for you is, how much room do you have? Are you building on a 4' x 8' sheet of plywood or foam? Do you already own HO scale rolling stock? If so, what is it?

F.Y.I.
I made my own radius templates out of poster board. I made a compas from a wooden yard stick by drilling holes in it to hold a nail at the pivot and a pencil at different radi. They are 2 1/2" wide (that is my track center spacing for curves) so each edge will help me mark my center line. But now I'm getting off the subject here.

You can e-mail me if you have any other questions.

[mrgstrain]

Hi Mark I just started put my new layout up. My space restrictions will not let me use 22in radius, I am useing 18in, you have to go with what room will allow. Iam useing Atlas sectional & flex track. So you my be restricted on what you can roll on down the road, I am so you build your railroad with in those restrictions. 22 does look nice but takes more room. By the way all my rail is BRASS. Good luck.

MRGSTRAIN

[mrgstrain]

Hi Mark I just started put my new layout up. My space restrictions will not let me use 22in radius, I am useing 18in, you have to go with what room will allow. Iam useing Atlas sectional & flex track. So you my be restricted on what you can roll on down the road, I am so you build your railroad with in those restrictions. 22 does look nice but takes more room. By the way all my rail is BRASS. Good luck.

MRGSTRAIN