DCC FAQs - for beginners

These are in no particular order right now. If you are a beginner, your question is probably here. If not, email me and I'll add it!

I have this section here because many people now use DCC in G scale, since often they used it in a smaller scale.

Why does my locomotive run so slow on DCC?

1. The DCC system can use a couple of volts from input of power supply to the output to the rails.
2. The decoder in your loco can lose a couple of volts between the track and the motor.
3. At top speeds a couple of volts can make a difference of 10 scale miles an hour or more.
4. Your locomotive was pretty slow already, like Aristo 6 axle diesel locos.
5. your DCC voltage is too low, aim for 24 volts DCC on the rails.

How do I know what voltage is on the rails? My meter reads funny.

DCC is a form of AC, but not exactly like the sine-wave shape of the AC in your wall outlet. It is a square wave of varying frequency. Ordinary (read cheap) meters cannot measure DCC track voltage correctly. Your meter must say it is a "true RMS reading AC voltmeter". You can buy one of these (usually over $100), or get the RampMeter from Tony's trains, that will measure DCC and DC and AC and amps. Highly recommended. Barring that, you can hook a full wave bridge rectifier to the rails (the ac inputs) and then read the resulting DC on the + and - outputs of the bridge with an ordinary DC voltmeter. You might want a small filter cap on the DC side.

Why doesn't my locomotive run?

This is the most common question, frequently associated with no more information. You need to check your installation out, start from the tracks to the decoder. Put the decoder on the programming track and see if you can communicate with it. If not, STOP and check your wiring. 

Some decoders, like the QSI, have a "startup sequence" and you need to "start" the loco before it starts making noise and moving. Likewise, many decoders (again like the QSI) have "Disconnect" or shutdown commands that will "disconnect" the motor, like it is neutral. In all kindness: read the dang manual!

How do I choose a system?

There is a lot of history in DCC, and many different systems. While the fundamentals are all the same, there are wildly different implementations of how you use the throttle.

Each "camp" believes it is the best, of course. Be sure to try to see and operate different systems before making a decision, it takes a fair amount of knowledge to make the "best" decision, and MOST companies try to "lock you in" to their unique features. It's good and terrible. Extra features are nice, but can severely limit your options as you expand.

Read up on the DCC "entry" page to get started: DCC "entry" page

Space for your layout - how much do I need?

First and most important advice: "grab" all the space you can.

The absolute most common mistake is having your curves too tight:

LGB GG-1 on 4 foot diameter curve.

Even though you can find track that makes a complete circle in 5 or 4 feet (diameter), unless you want a "toy-like" layout with severe restrictions on what you can run, you need bigger curves.

Just plain do not do the 4' diameter curves unless someone is holding a weapon to your head.

Reasons for broader curves and using more space:

• The broader the curves, the more reliable the operation of your train is, less derailments.
• You can use larger locomotives on broader curves.
• You can run longer trains on broader curves.
• Long trains look funny on a short track.
• The the longer the mainline the longer it takes for a train to make one lap. There's very little fun in watching a train chase it's tail and come by every 30 seconds.

Next issue: grades

The next most common mistake is grades too steep. Mainlines rarely had over 1% and usually never over 2%. Logging railroads with geared locos maybe 5-7% or so.

You need to measure to see what you think is not so steep. Try to keep your mainlines to 2% or maybe 3%

Also remember percent is NOT the same as degrees. 3% is just 1.7 degrees. Be careful of what you are measuring!

Here's an online calculator to convert degrees <> percent https://rechneronline.de/winkel/percent.php

The Real World

You need to realize how "far" we are from the prototype in curves "sharpness" to see why sharp curves make unreliable operation.

In the real world, curves are measured in degrees. Bob Hyman on MLS wrote:

A 1° curve has a radius of 5729.65 feet. Curves of 1° or 2° are found on high-speed lines. A 6° curve, about the sharpest that would be generally found on a main line, has a radius of 955.37 feet. On early American railroads, some curves were as sharp as 400 ft radius, or 14.4°. Street railways have even sharper curves. The sharpest curve that can be negotiated by normal diesel locomotives is not less than 250 feet radius, or 23°.  Even narrow gauge lines like the Rio Grande Southern had maximum curvatures of 24°, and there were only two curves that sharp … one at the Ophir Loop and the other at Trout Lake.

To convert degree of curvature into an actual curve radius, simply take the sine of ½ the degree of curvature and divide it into 50 feet. The result will be the prototype radius in feet. To find the model radius, just divide the prototype radius by the model scale.

A much simpler approximation is to divide the degree of curvature into 5729.65.  The resulting number is the prototype radius in feet.  Then divide that number by your scale and you have the model radius.   

Let's assume 1:29 scale. Even a 6° curve comes out to 32 foot radius. To us in the hobby, that is HUGE, and that represents a very broad curve. Conversely, a 5 foot radius is almost 40 degrees, which would never be found in the prototype, but is considered somewhat broad in our hobby.

So, you need to broaden your curves all you can, and it will pay off in appearance, operation, reliability, and just plain enjoyment.

When planning:

• Spend time thinking into the future. Yes, many people recommend that you just lay something down right away.
• Is there ANY time in the real world where doing a little planning is BAD? Resist the temptation, and look into the future. Don't just rush out and lay down a small oval, and then hope to expand on it later.
• It's a lot less fun tearing up an existing layout to move it around.
• Look for places to expand, you always need more room than you have.
• Look for ways to broaden the curves, places for passing sidings. 
• Don't start with a small loop if you don't need to, look at where you will be in years to come, and see how to implement it in phases.
• Don't put the track where you cannot maintain it, avoid places that might have to be torn up, or where there is water drainage places.
• Don't do anything less than 10 foot diameter curves in a new layout.
• Spend the $99 for a track planning software, that lets you "snap together" pieces of track and do "what if" very easily, it's hard for anyone to visualize without some form of drawing.

Scale, what is this all about? Do I care? How do I tell?

• What scale is all this stuff?
• Why should I worry about scale?
• What's available, how will it affect me?

These are all questions you should address, since the supply of models is limited, unlike a scale like HO, where virtually everything is available.

Basically, you want to decide if scale is important to you, and how important.

(If you are coming from another scale, the following stuff will seem strange, almost sacriligious, but read on)

Often things are called "G Scale".... this can be many different scales, that commonly "fit" on 45 mm gauge track.

(there are also "scales" that run on O scale track (32mm) for example 16mm scale, which is 16mm to a foot, and is about 1:19 scale and represents about a 2 foot narrow gauge... it really cannot get much more confusing.)

So let's stick to "G Scale", running on 45 mm track also often known a "Large Scale" but stick with "G Scale"

What scales run on 45mm track?

Well, mostly 1:20.3, 1:22, 1:24, 1:29 and 1:32 !!!  (These are the common ones!!)

If you are into American narrow gauge steam locomotives, you are in luck, since there are a number of good models available, all narrow gauge. Many of them are somewhat expensive, but there are some good inexpensive ones available from Bachmann. The higher priced stuff is from Accucraft, and a few others. The "reasonably priced" stuff is from Bachmann. The 45 mm track works out to the right size for narrow gauge in 1:20.3, pretty much the standard narrow gauge you can get in the US.

If you are into standard gauge trains, and exact scale is important, you have the possibility to buy equipment, but your costs are going way up. MTH makes/made a nice line of models in 1:32 at moderate to high prices, but they are about the only "reasonably priced" alternative in 1:32, and also a lot of "liberties" have been taken to allow locomotives navigate "toy like" sharp curves. (This is from the MTH heritage in O scale). MTH is not terribly active in the #1 scale, and no new locomotives in a while. They have very nice sound systems, and a nice (but non-standard) remote control. Recently they have added DCC compatibility although a bit flawed. You cannot buy the locos without the extra electronics. Your only other locomotive and rolling stock choices are much more expensie, Accucraft and Aster and several other high end manufacturers make beautiful models, but these can run into thousands of dollars for a locomotive. Basically be prepared to spend more on cars and locos.

If you are into standard gauge, and exact scale is not so important, USA trains, Aristocraft  and AML (American Main Line made by Accucraft) make excellent inexpensive models in 1:29. The trucks are a bit narrower than scale, since the track should be theoretically wider for this scale. Most people accept this in exchange for the large selection and good prices. More and more companies are build in this scale, like Gibert LeCroix' GLX Models.

The 1:29 stuff came about sort from the "wow" factor. If your layout is on the ground, the 1:29 standard gauge locomotives look much larger than the exact scale 1:32 stuff. There is also more available in this scale than any other.

(of course, if you are in narrow gauge, then the 1:20.3 is even larger, more wow!)

If you do not worry too much about scale, you can mix various scales, but right next to each other they can look funny to most people.

The oddball scales look pretty strange when mixed with other scales.

Worth mentioning here is LGB, who pretty much is responsible for the popularity of this part of the hobby. They often have products in a compromise scale in terms of width and height, but shortened to run on their tightest curves. Next to a 1:29 model, they often look short and toylike but wider and taller. This is excellent quality stuff, but if you want scale appearance, this won't be your favorite. They have gone into bankruptcy twice in recent years.

My best advice is go to someone's layout, have them put the different scales next to each other, look at the trains and see what floats your boat!

Bottom line: run what looks good to you.

Roadbed design & support, elevated or on the ground?

This section is about the 2 basic types of layouts, and will try to help you decide whether your railroad will be elevated or not?

This is your first decision. Items to consider:

• Will bending down to work on the layout, place trains, correct derailments, be a problem?
• Do you have drainage problems, get heavy leaf accumulation, or snow where track on the gound will be a big problem?
• Do you have pets or animals that will wreak havoc with your track?
• If you plan to run live steam, the greater attention the locos need may be a factor.
• Is your yard so "heavy" with slopes that grades would be a lot over 2%. Also steam locos run best on dead level track.

Elevated layouts

Elevated layouts are visually appealing since the trains are up higher and more visible. They are easier to work on. Your trains are closer to eye level and look bigger.

They can also be a lot more work, especially initally. Many people need tons (literally) of rock or soil to elevate their track. Normally retaining walls are needed.

If you plan to run steam, an elevated railway is almost a must, due to constant attention to water, fuel, and inspection. Steam locos really like level track, and this is easier to do when you elevate the track, unless your entire yard is dead flat.

Options are posts with with wood or metal between them to support the track. Relatively inexpensive, not really pretty though. Be sure to use plastic or metal, not wood for the posts. Be SURE to put the posts BELOW the frost line.

The other option is to build up the earth to the height you want, and this will almost necessitate retaining walls. When you do this, you probably want some sort of support underneath, since the earth will DEFINITELY settle. 

You can make "ladder" track (which is really roadbed), 2 parallel "ribbons" of wood (cheap but rots) or synthetic wood (expensive, support twice as often) that supports the track. You can then backfill with earth to make it look nice. The dirt, IF compacted well, will help support the ladder system. You can also make the ladder system self-supporting. I would not recommend wood at all. 

Roadbed on the ground

There are many different ways to support the rails.

Most importantly, you will want something that weather, animals and kids do not make a maintenance nightmare.

If you live in a mild climate, a shallow trench filled with small gravel might be all you need (works for me in San Diego). You need good drainage to make sure rain does not wash things away.

For wetter climates, you might put concrete pavers under the track, or pressure treated lumber bolted together. One famous garden railroader makes poured concrete roadbed. (Hi Marty!) This works well where frost heave is minimal.

For areas that get frost heave, you might have to add supports that go below the frost line.

The best thing here is to contact fellow modelers in similar climates and visit their layout or converse with them to see what works and how much effort you have to go to.

In general, the more stable your base, the more time you will spend running. Running long trains or reliable operation needs nice smooth trackwork that is level side to side and is free of abrupt bumps or dips.

Ballast

Ballast greatly improves the look of the track.

There are many variations on the type of stone and size you can use, but follow these guidelines:

• Do not use any smooth, rounded stone, it will shift position.
• Do find stone with sharp edges
• Generally, the harsher the climate, the larger the stone you need.
• Do NOT use any limestone or oyster shell. This is very alkaline and can damage the track. 

Many people use a coarser grade for the base or sub-roadbed, with finer stff on top.

Crusher fines or chicken or turkey grit works well and looks good, but can wash out under heavy rains.

Some people mix glue or cement with thier ballast to keep it from blowing or washing away. Again, refer to modellers in similar situations.

I use a coarse mix for my ballast. It is larger than prototype, just fits between the ties, but it locks in solid and does not wash out. Since I use stainless steel, my track cleaning is usually done with a garden hose!