# Newbie Question 18" Radius?



## PRR-GG1 (Feb 5, 2015)

I am a former O gauge 3 rail (Lionel) operator changing to HO because of space considerations. Looks like my new HO layout space will 3.5' to 4' by 7'. Thata not a lot of space. I've considered N scale but its just too small. Anyway I have some general questions:

1. I'm planning to use 18" radius curves. How much does that limit me as far as engine choices, passenger cars (may not have space for those anyway), etc? I've noticed that many HO ads to not mention minimum radius whereas Lionel was very specific in their ads
about that.

2.Are there 18" radius turnouts? What is the radius of a #4 turnout? 

3.My Modeling period is 1910's - 1920's so I'm looking at steamers. I want to use
DCC (Lionel Legacy convinced me of that), but I'm wondering if there are any DCC equipped
small steamers 0-6-0's, etc that contain DCC electronics or does space not allow this on smaller locomotives?

4. One general DCC queston. Is it true that a DCC Equipped locomotive with sound regardless of the make of decoder board used can be operated with any brand of DCC control set (digitrax, NCE ,other)?

5. One last HO to O conversion question. What is a 4' x7' Ho layout equivalent to in O gauge space? Since HO is roughly 1/2 of  O in size can you say that 4' x 7' =28 sqft is equal to 56 sqft in O gauge or is it that 4' x 7' in HO is equivalent to 8' x 14' in O?

I would appreciate any type of feedback that you guys may have. Thankyou.


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## tkruger (Jan 18, 2009)

Small steamers such as 0-6-0 and down will not have an issue. Anything over X-6-X may or may not have an issue depending on how it is built. I have older decopods (2-10-0) that can take an 18r curve since they use blind drivers. Most modern ones require 22r or larger for the same locomotive.

There are turnouts available that equal 18r curves.

DDC decoders are often placed in the tender.


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## Old_Hobo (Feb 20, 2014)

The 4' x 7' layout in HO would scale up to about 7' x 12.5' in O scale....almost twice the size (1:87 vs 1:48).....if HO was 1:96, it would be exactly twice the size....

As for the turnout number, I don't know what the equivilents are to radius, but this graphic should explain it:


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## Shdwdrgn (Dec 23, 2014)

The Atlas snap-switches are probably the most common 18" radius turnouts. From what I've been seeing, the numbered turnouts (#4, #6, etc) don't directly relate to a specific curve radius, making it difficult to use them as part of a longer fixed-radius curve.

I'm sort of in the same boat -- I have a much larger space available, but I am working on a pretty specific type of layout within that space so there are several curves around 18". Fortunately I was already planning on smaller locos (2-6-0) and 40-50 foot freight cars.


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## MtRR75 (Nov 27, 2013)

I am also modeling the 1910s-1920s. I have a double-loop layout made from Atlas snap track and snap switches, with 18"curves. I run DC, so I can't help with the DCC issues.

I have an IHC 2-6-0, a Bachman 2-6-2, and a Bachman Spectrum 4-6-0. All run fine on my layout. I also have two IHC 4-6-2 locos. One runs fine. The other one sometimes shorts out briefly when going through some of the snap switches. This seems to be a function of the snap switches. You would do better to use the non-snap switch Atlas turnouts or turnouts from another manufacturer.

I also have two Bachman Spectrum 2-8-2 locos. They run fine on my layout, except the the front truck on one sometimes derails. This is again due to the design of the snap switches.

My biggest loco is a BLI 2-8-2. I also runs fine on my layout.

The drivers on some of my larger locos can shift a little from side to side, allowing the loco to stay on track on 18" curves. Look for that feature on your locos, but it never seems to be advertised. You have to ask the company or pick the loco up yourself and play with the drivers.

Some larger steamers have no flanges on some of the drivers to allow them to traverse tight curves, but I can't comment on them, as all of mine have flanges on all wheels. (I assume that is what tkruger measns by "blind drivers".


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## DonR (Oct 18, 2012)

The Bachmann 0-6-0 is available with DCC AND SOUND.

http://www.trainsetsonly.com/page/T...e7VIEFshELDJ7m7bIi8D3Psm4La4RuB3HoaArBs8P8HAQ

It's a nice little loco. You'll enjoy using it as a switcher.

Most DCC including sound is compatible with most DCC controllers.
They follow, for the most part, NMRA
standards. 

Bachmann EZ is compatible but limited in features. Most HO guys
go with NCE or Digitrax.

Stick with 4 axle diesels and small steamers if you are limited
to 18" radius. Be careful about what passenger cars you buy.
The 70' Athearn silver side cars are ok. 80 foot cars may be
troublesome.
Long freight cars could be troublesome on 18" as well.

Don


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## Old_Hobo (Feb 20, 2014)

Those "old time" passenger cars (Arch Roof cars, as they call them) from Roundhouse would be good on 18" radius...they are shorties.....they are a scale 60ft in HO....









Or the Roundhouse "Overland" cars....they are a scale 50ft....


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## Howard1975 (Jan 6, 2014)

Because of your 1910's-1920's time frame, you could also go with the old-time 34 foot Overton passenger cars, made by Athearn (they used to be made by Model Die Casting/Roundhouse). They are not entirely prototypical, but some roads did have very short passenger cars. 

The 50ft Overland cars (and longer) are much more common and prototypical for that era. 

Howard


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## Cycleops (Dec 6, 2014)

Why don't you consider doing a point to pont layout? Then you won't have issues with min radius for your locos and it will look more realistic with no overhang when negotiating curves but will give you more operational fun shunting.

Regarding DCC decoders, they will work with whatever controller you buy. Just that some additional features may be available when using the same brands together. Decoders are now incredibly small so you should have problems installing even in the tightest spaces. With a tender layout you have a good space to install a speaker for sound.


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## PRR-GG1 (Feb 5, 2015)

Thanks to everyone for your responses. I've still a lot of planning to do before construction begins, I'll probably be back with more questions as the project moves forward.


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## Aberdeen (Mar 23, 2015)

Looking at Kato’s HO track list, I can see that:

#4 turnout = 21.5” radius,

#6 turnout = 34 1/8” radius.

I have Kato #4 turnouts; a 21.5” radius curve track matches it exactly.

My problem is that 21.5” radius is the tightest that Kato makes. If (when?), I move from the den floor to a 11’x12’ basement room, I’ll have a U-shaped layout (maybe E-shaped) and need tight curves to run in a loop, which I want. 

Atlas Snap Track’s 15” radius would be ideal; I’d have to do a transition from my Kato. I’m definitely a Snap Track or EZ Track guy. Any other alternatives or thoughts?


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## dsertdog56 (Oct 26, 2014)

Again, it's merely an opinion here...but I've recently installed a bunch of Snap switches intermixed with a few "Custom line" Atlas turnouts.
Everything went together great, until I started running trains on them.
All my steam engines hate them. The radiuses (throats?) are very tight for pilot trucks and the molded frogs and rerailers all had to have their grooves cut deeper and casting flash removed around the metal rails so that good contact could be made. In my exuberance (and anger) I may have over cut a couple of frog points and now some of my lighter freight cars derail. The custom line turnouts are marginally better but still needed some massagiing.
When I redo my mainline I'm going to try Shinohara switches. My dad used these on our last layout back in the day and I don't remember any issues.


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## Cycleops (Dec 6, 2014)

It should be possible to make a transition from Kato to sectional track from another manufacturer if using the same code rail. You could maybe use a cork roadbed to take up the difference. Perhaps someone on here's who has attempted this can advise.


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## Southern (Nov 17, 2008)

#4 Yes most use NMRA standard


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## MtRR75 (Nov 27, 2013)

Aberdeen said:


> Atlas Snap Track’s 15” radius would be ideal; I’d have to do a transition from my Kato. I’m definitely a Snap Track or EZ Track guy. Any other alternatives or thoughts?


When you design your layout, try to go with the Snap Track 18" radius track, instead of 15" radius track. The 18" radius is popular because you can easily fit full 180 degree curves on a 4' x 8' board. So a lot of locos and rolling stock (but not all) are designed to run on 18" curves. The 15" radius track not used nearly as much, so most manufacturers do not consider it when designing locos and rolling stock.


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## MtRR75 (Nov 27, 2013)

dsertdog56 said:


> Again, it's merely an opinion here...but I've recently installed a bunch of Snap switches intermixed with a few "Custom line" Atlas turnouts.
> Everything went together great, until I started running trains on them.
> All my steam engines hate them. The radiuses (throats?) are very tight for pilot trucks and the molded frogs and rerailers all had to have their grooves cut deeper and casting flash removed around the metal rails so that good contact could be made.


Here's something you might consider...

I have Atlas snap switched on my layout, and I run steamers almost exclusively. Some of my steamers have their electrical pick-ups in the tender. Those streamers run much smoother than the ones that use the drive wheels to pick up the power. I am considering moving the pick-ups into the tender on more of my steamers, when I get the time and learn how to do it.

I do sometimes have issues with front trucks derailment. I find that this is more complex, than the electrical pick-up problem. There are several factors (both track and loco) which can contribute to this problem, and the solution seems to be different for each steamer. PM me if you want the long version of what I have learned.


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## CTValleyRR (Jul 26, 2014)

A little more on turnouts. The Atlas Snap Switches, being designed for oval layouts, have a 1/8 diameter 18" radius curve as the diverging leg. They also make snap switches with 22" radius. Most other manufacturers make a more prototypical turnout where the diverging leg comes off at an angle, not a curve (refer to Old Hobo's illustration). The diverging track is straight, not curved.

A 4x7 is a pretty dinky HO layout. Any chance you could use an alternate layout pattern, like a donut?


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## dsertdog56 (Oct 26, 2014)

MtRR75 said:


> Here's something you might consider...
> 
> I have Atlas snap switched on my layout, and I run steamers almost exclusively. Some of my steamers have their electrical pick-ups in the tender. Those streamers run much smoother than the ones that use the drive wheels to pick up the power. I am considering moving the pick-ups into the tender on more of my steamers, when I get the time and learn how to do it.
> 
> I do sometimes have issues with front trucks derailment. I find that this is more complex, than the electrical pick-up problem. There are several factors (both track and loco) which can contribute to this problem, and the solution seems to be different for each steamer. PM me if you want the long version of what I have learned.


Interesting...what I discovered after trying to watch my steamers go back and forth over the same inch or two of track is that the drivers were being lifted off the track by the casting flash. I could easily slide an .006 feeler gauge between the rail and the driver. Of course any kind of gap means stall. Dads older Rivarossi type engines with their deep drivers were particularly hampered

Things run much better now, but a better quality turnouts would have made early run sessions a bit more enjoyable.


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## JNXT 7707 (May 5, 2013)

Aberdeen said:


> Atlas Snap Track’s 15” radius would be ideal...


You may have already gotten the point from other posts but I'll add this just as a general thought - unless you are running small trolley cars or VERY short locomotives and rolling stock I would avoid 15" if possible. I know space considerations have the last word, but always use as large a radius curve as you can, even if it is a challenge. 

On my first layout I always regretted relying on 18" curves to "make it fit". My love of long equipment compounded that mistake - 85' passenger cars just don't look right on 18" curves - even 22" is a stretch.


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## traction fan (Oct 5, 2014)

*18" Radius, Heck that's a broad curve to me.*

I don't know how firmly committed you are to HO scale. I too model the 1920s with an emphasis on passenger operations, with 85' heavyweight cars aplenty. The difference is my railroad is N Scale. My minimum radius is 16" and it will reliably accommodate long cars and locomotives. Micro trains Co. (an offshoot of Kaydee for you HO guys) offers a good selection of beautifully detailed, smooth running passenger and freight cars. Kato has a stable of excellent diesel and some steam locos plus gorgeous complete, famous passenger trains like the Super Chief, California Zephyr, Empire Builder, Etc. Other manufacturers offer a wide selection of rolling stock and accessories. Your small layout space will look a lot better in N scale.

Just another option to consider. Welcome to a great hobby in any scale!

Traction fan


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