Hey guys and gals, I have a radius question for you, I'm having trouble with building the CORRECT radii for my layout, my curves would look good at first until I run one of my 6 wheeled locos and theres the perverable derail!!!!! What are the steps in making the best radii, My layout is going to be in Nscale. Thanks for the help. Trainsrme1
From what I gather "N" scale is half of "HO" scale. So 9" and 11" radi should be the norm. But as I work in "HO" scale that's just a guess. I do know the smaller the scale the easier it is to get it wrong and with my fat fingers I'll stay with "HO".
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TrainsRMe1 Hey guys and gals, I have a radius question for you, I'm having trouble with building the CORRECT radii for my layout, my curves would look good at first until I run one of my 6 wheeled locos and theres the perverable derail!!!!! What are the steps in making the best radii, My layout is going to be in Nscale. Thanks for the help. Trainsrme1
I have no clue what a "perverable derail" is, but I assume you are trying to communicate that your longer locomotives cannot handle whatever radius you are using.
What is considered a bare minimum radius for N scale is 9 3/4" radius (N is not quite half of H0, but is the equivalent of H0 divided by about 1.8 instead of divided by 2).
What curve radius would make sense on your layout depends on what you are running. Rule of the thumb is that curve radius should be about 3 times the length of longest engine or car for reliable running, up to about 5 times the length of the longest engine or car for reliable hand-off coupling (like in a curved yard track).
If you are running cars that are 89 feet long, then those are about 89 feet x 12 inches/foot = 1068 inches. In N scale (1:160), that would be about 6.7" long - so 3x curves would need to be about 20" radius.
If you are running engines and cars that are about 60 feet long, then a good radius for reliable running would be 2/3rds (since 60/90 is 2/3, eh?) of the radius above - i.e about 13" radius.
Bad track work would also help derail engines and cars. If you cannot get a smooth curve using flex track, use sectional track for the curves.
Smile, Stein
steinjr TrainsRMe1: Hey guys and gals, I have a radius question for you, I'm having trouble with building the CORRECT radii for my layout, my curves would look good at first until I run one of my 6 wheeled locos and theres the perverable derail!!!!! What are the steps in making the best radii, My layout is going to be in Nscale. Thanks for the help. Trainsrme1 I have no clue what a "perverable derail" is, but I assume you are trying to communicate that your longer locomotives cannot handle whatever radius you are using.
TrainsRMe1: Hey guys and gals, I have a radius question for you, I'm having trouble with building the CORRECT radii for my layout, my curves would look good at first until I run one of my 6 wheeled locos and theres the perverable derail!!!!! What are the steps in making the best radii, My layout is going to be in Nscale. Thanks for the help. Trainsrme1
He means to say the "proverbial" derail; that is, well known so as to be stereotypical.
Rich
Alton Junction
Not sure about "N" scale but for me and my "HO" scale I run alot of 85' passenger cars and mallets on my layout so I run a min radii is 36" for me. Most are around 40" on the mainline, due to space restraints can't run any bigger size radii. All of my 6 wheeled engines as well as my 2-8-8-0 and 2-8-8-2 run just fine on the 36" radii. Also are the curves banked? If so what degree of angle do you have on the banking? remember flat curves trying to hold a train at speed doesn't work too well if you are running at speed, slow speed no problem but the law's of gravity still apply with speed and curves. I would recommend a radii of 20-22" that should handle the problem of derails due to tight radii curves. I use flex-track when I build my curves, it seems to work much better than using sectional pieces of track, plus you can customize the curve to open it up more this way where sectional pieces won't allow for it. Also how is the roadbed? is it stable or is there any "flex" in it when the engines roll across? I have a customize track car I made that I use to check for flaws and flex on my layout. I bought a dummy sd-40 from Athearn's and removed the shell and added weight to the frame so that it weights 25% more than my heaviest engine and use it to check the tracks if there is a flaw it will show up quickly when you roll it over that area. don't know if any of this helped you, but thought I would put in my two cents worth.
The smaller the scale, the less tolerant 6-axle diesels and steam engines are of tight curves and kinks in curves. While 4-axle diesels can usually negotiate these track laying faults without a problem, you need to broaden the curves and eliminate the kinks in order to stop derailments with 6-axle diesels and steam engines. This is especially true in HO scale and more so in N scale.
In trying to eliminate kinks in your curves, note where the problems consistently occur, and why, by running the engines slowly through the curves to see what is happening.
With steam engines, it is normally the pilot trucks that lift up first and the driver wheels follow. Other times, the pilot trucks hold to the rails, but the driver wheels cannot hold the rails because of kinks or tight turns.
With 6-axle diesels, the "wheelbase" from the first to the last of the three wheelsets on a truck are locked into a fixed position and simply cannot hold the rails on kinks and tight turns.
Whatever the reason, and whatever the type of engine, at slower speeds the porblem may not occur or, if does, the speed is often slow enough to permit the engine to recover because the lifting action of the wheels falls back squarely onto the rails. But, at higher speeds, the engine has gone past the trouble spot before the wheels can return to the rails and by then the position of the rails below the wheels is different. Thus, the proverbial derailment. It's a basic law of physics.
Broaden those curves and eliminate those kinks.
richhotrain He means to say the "proverbial" derail; that is, well known so as to be stereotypical.
Ah, "proverbial derailment". That is probably what he meant. Thank you.
Are you using flex track or sectional? Do you know what the radius is on the curves where you're having the problem? Do you see any kinks in the track, particularly at joints between track pieces, or where the curve meets the straight track?
I had a temporary layout built with Kato Unitrack, which is generally bullet-proof. I once ran a set of Con-Cor PA-1s through the equivalent of 13.5" radius. The engines made a noise half between a squeak and a squeal as they passed through the curves. My Life-Like SD-7s were a tad more tolerant, but not by much.
Dan
Our tiny models are not very forgiving of undulations, wobbles, kinks, and improperly lapped joints.
First, you need to know the recommended minimum radius for your rolling stock.
Next you need to be able to lay good solid track on a good flat foundation. If the track elements are not fully supported below them, the passing engine will cause it to dip and therefore to wobble. Joints, especially, need to be kept from dipping and rising. It really affects continuity at the points eventually as the joiners will splay and not make contact.
You can't make your engines and longer cars go around curves that are not at or above the minimum radius at some point along the curve. One or two may make it, but one will usually hang up, or it will come uncoupled, or it will derail.
To make curves with flextrack, you must first draw the centerline accurately. Use a string and pencil and a screw pivot at one end of the string, or use a wooden yardstick and drill two holes in it, one right near the end, drive in a sharp small screw for a pivot, and somewhere along the yardstick drill several holes large enough to put the tip of a pencil through so that it will mark your roadbed. Use an indelible marker to label each hole's distance from the screw pivot. Then, lay your flex curves along that centerline so that the tiny nail holes in some ties run right over that centerline.
There ya go...!
Crandell
Thanks Crandell, and everybody, I don't know why, but I have a heck-a-time building good curves, one more question, with the string and pencil, would I start the radii mark from a middle pivot point?? Thanks again for the Help!!!!
I'd suggest using a yardstick instead of a piece of string. That way, you don't have to worry about the string sagging and accidentally making a sharper radius than you were planning.
A simple method is to tape a finishing nail at the end marked 1, then tape you pencil over the inch mark of the radius you want.
Then when you're done, throw away the tape and no one in the house will be any wiser that you requesitioned household equipment for model railroading uses!
Eric
I wish I was a headlight
On a northbound train
oo-OO-OO-oo I'd suggest using a yardstick instead of a piece of string. That way, you don't have to worry about the string sagging and accidentally making a sharper radius than you were planning. A simple method is to tape a finishing nail at the end marked 1, then tape you pencil over the inch mark of the radius you want. Then when you're done, throw away the tape and no one in the house will be any wiser that you requesitioned household equipment for model railroading uses! Eric
steinjr If you are running cars that are 89 feet long, then those are about 89 feet x 12 inches/foot = 1068 inches. In N scale (1:160), that would be about 6.7" long - so 3x curves would need to be about 20" radius. If you are running engines and cars that are about 60 feet long, then a good radius for reliable running would be 2/3rds (since 60/90 is 2/3, eh?) of the radius above - i.e about 13" radius.
Not disagreeing with Stein's numbers, I would just like to point out that those suggestions are for the minimum radius. The "normal" radius should be larger than that. For example if your minimum is 20" radius you should try to make normal curves 22-24" radius with broader curves where possible. If the minimum radius is 13" then the "normal" radius should be 15-18" radius with broader curves where possible.
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TrainsRMe1 ...with the string and pencil, would I start the radii mark from a middle pivot point?? Thanks again for the Help!!!!
...with the string and pencil, would I start the radii mark from a middle pivot point?? Thanks again for the Help!!!!
Yes, exactly. You have to fiddle with a pivot point inside the curve you desire so that you get the radius you desire WHERE YOU WANT the curve.
As stated above, the string method is quick and simple, but it has some problems. String stretch, or sag if you are sloppy, could compromise your nice curve somewhat. It isn't going to be a show-stopper except when very near the minimums engineered for the rolling stock. Best to be as accurate as possible. You could use fishing line, say 5 pound test, which you would have to work hard at to stretch. Sag is still a potential problem.
That is why the wooden yardstick, or wooden lath, is best. For one, you can place its pivot point on one end on something off the layout if that is practically where the center of the circle would be for the arc you are making. That is how most of us do it...we have curves turning around corners in our benchwork, and this means the pivot point has to be closer to the person operating the railroad.
As I described earlier, very close to one end of the lath/yardstick, you drill a tiny hole, just enough to keep it from splitting when you drive a small screw for a pivot. OR, just next to it, you could drill a larger hole that the larger machine screw on the panhead of a photographic tripod would fit into...your off-bench pivot point! Then, depending on your scale, you drill at appropriate intervals a whole bunch of other holes further up the lath, say starting at 8" for N scale, and drill a hole every inch until you run out of lath length. Inches are inches in any scale, and if you ever build an HO layout, your holes will still be an inch apart for the different radii.
Since you're having trouble doing curves, you might want to look at Kato Unitrack. In N they offer a lot of track products, including double-track pieces. One problem when using flextrack is that one slight 'kink' can make engines derail...even though it looks like say 11" radius, one kink might mean that for a few inches it's actually 8" radius.
In general, the largest curves you can fit in, the better. 15" or larger curves and No.6 turnouts will probably mean no more derailments (or at least far fewer).