12 WHEEL LOCOS

[nfmisso]

QUOTE: Originally posted by trainboyH16-44

ic

QUOTE: Originally posted by CP5415

but SD40-2 should be no problem.
Gordon

I was told that Kato SD40-2s only run through a 21" radius curve or larger. Is that true?
Trainboy

Very likely, they have closer to scale truck spacing than Athearn. Athearn's truck spacing is over a scale foot short to provide clearance truck to steps. In addition, Athearn's fuel tank is short, for the same reason.

[Adelie]

rob,

I found the references in Track Planning for Realistic Operation. The offset for 18" curves is 3/8" and the easement length of 12" (6 on each side). So, the numbers I used earlier are close. To give you an idea, the next step up is for 24" curves, where they recommend 7/16" over 16" of length.

If you want the relevant paragraphs and diagram out of the book, let me know and we can swap email addresses. I can scan the pages (2 of them) and ship them off to you.

[trainboyH16-44]

ic

QUOTE: Originally posted by CP5415

but SD40-2 should be no problem.
Gordon

I was told that Kato SD40-2s only run through a 21" radius curve or larger. Is that true?
Trainboy

[selector]

Super job, Adelie. My compliments to you!

[Adelie]

I hope this does not turn out like War and Peace. It is actually not hard to do (especially with two people), but it is hard to describe.

You need a pencil, a wood yardstick or similar piece of flexible strip wood or metal, and either a second set of hands or some nails.

1) Drill a small hole (1/8" is good) into the middle of the yardstick at the 1/2" mark. Then drill additional holes at your radius (so for 20", drill the hole at 20-1/2") and at an offset from the radius. I don't have "Track Planning for Realistic Operations" with me (I'm goofing off at work), but the offset is probably 3/8" or so for that curve, so drill the hole at 20-7/8 in the yardstick.
2) Draw your curves on the plywood or subroadbed using the yardstick. Drive a common nail into the sheet of plywood at the centerpoint of the curve, insert the yardstick over the nail using the hole at the 1/2" mark, and then stick a pencil in radius hole (20-1/2" mark for example), draw the curve by swinging the yardstick with the pencil. Repeat for the offset curve (20-7/8"mark ). You don't need to draw the entire offset curve, but only about a foot or so from where it will join the straight track that leads up to it (the point where the straight and curve connect is called the "point of tangency").
3) Draw your straight section from the offset arcs, not the radius curves (use the 20-3/8" radius curves).
4) Draw a line 90-degrees from where the straight and 20-3/8 curve meet (the "point of tangency") towards the center of the curve. It only needs to be long enough to intersect the inner curve (the 20" radius).
5) Measure back from the "point of tangency" line about 6-1/2" (I drew one of these on Cadrail, and it used that distance)on both the straight section and the 20" curve. So, you will have a mark on the straight 6-1/2" before it enters the curve, and on the curve 6-1/2" before it intersects with the point of tangency.
6) If you have a second set of hands available, place the yardstick on edge on the straight section and have them hold it at the mark you just made. Then flex the other end of the yardstick on the 20" curve, and have them hold that end at the corresponding marked 6-1/2" back. It is important that they be reasonably accurate holding the straight part straight and the curve part on the curve. The yardstick will naturally flex between the two points at a nice easement. Draw a line from the straight section, along the yardstick, to where it joins the 20" curve (thus, the easement will be roughly 13" long).
7) Repeat this process for all curve-straight joints. If there are a lot of them, get a thick piece of posterboard or a piece of sheet styrene plastic and use the above process to draw the easement, along with about 6-12 inches of the adjoing straight and curve sections, on that and cut along the lines you drew. Then you can use this gadget to quickly draw the rest of them.

If you don't have a second set of hands, drive about 4 or 5 nails back from the 6-1/2" marks on both the straight and curve. I drive 3 on the outside, 2 on the inside, leaving enough room between the two rows for the thickness of the yardstick. Drive the nails on each row about every 2-3 inches apart. Then insert the yardstick between the rows of nails on both the straight and curve and it will flex away.

I hope to find some sort of graphic or condensed version of this that will make it clearer. It is actually pretty easy, but tough to describe. If I have confused you, let me know. It is really not that bad.

[twhite]

Adelie's suggestion is a really good one. Another alternative would be to get a Ribbonrailer radius gauge while you're laying out the flex--they fit between the rails, and come in radii from about 15" up to about 45" or so. You just place the gauge between the rails, slide it SLOWLY and spike down behind it. I use 34 and 36" Ribbonrailers on my layout, and haven't had any problems with it at all. You might consider getting a 22" ribbonrailer for easement and a 20" for the curve. But Selector's right--if you do decide to get some steam locomotives, remember, they're not as forgiving as diesels, because of their more rigid drive-wheel length. Most of the newer steamers from Proto, Specfrum and BLI will usually (and I stress the word USUALLY) handle a 22", though with considerable overhang.
Tom

[rob_c65]

Thanks Adelie. That would be great if you would post the how to. I will consider the flex..

[Adelie]

If you have 4' of width, you might consider using flex track and 20" curves with easements. They are a little bit of a pain to lay out (works okay with two people doing it or if you cut a template out of sheet styrene). It is certainly more work than stock 18 or 22 inch curves, but it might be worth considering, depending on the level of effort you want to put into it.

If you're not familiar with easements, it is a stretch of gradually increasing curve from your straight section into the curve. Makes entering the curve easier on the equipment. I'd guess you'd have better luck with eased 20" curves than straight 22 or 24" radius curves.

If you are interested, I'll post how I lay them out. Others out here may have better ways to do it, too.

[rob_c65]

Thanks selector. My concern was for the double main line I plan to build. Again, thank you for your suggestions.

Rob

[selector]

That's an interesting observation, nfmisso. I don't have the experience to counter that, but I suspect that you are correct. One would expect the more costly locos to have better engineering and therefore tighter tolerances.

For Rob, my local hobby shop (LHS in these forums) agreed beforehand to accept a return on anything I didn't use that was nor marked, nicked, etc..i.e., could be resold. That way, I didn't feel too worried about rising costs. if I needed it, I paid. If not, i could always rtuern it. That said, perhaps you can negotiate their return if you find that the 22" radius curves constrain you too much.

May I suggest that you use them on your main, if you will have one, and keep the 18" for passing, switching yards, industrial yards, and staging. The old railers will advise you to have lots of staging so that you can run the trains without impediment. I didn't, and now see the folly of my ways. (sigh)

[nfmisso]

Rob;

It depends on the particular model. Generally, the more expensive the model, the wider the curve required.

[rob_c65]

Thank you everyone for your input.

For Selector: I was going to use 18" curves becuause I have a bunch all ready and thought why not use them. I will go and purchase some 22" and see how they will fit into my plan. Space is an issue being I'm only going on a 4 ft width. Again, I appreciate your thoughts.

[selector]

My last message was getting long, so I ended it forgetting to add one last important point: you may decide to add steamers as you mature in the hobby. Some will, some won't. You'll want to use an existing layout (that tend to be costly to build), at least for a while. You could find that your steamer(s), unlike your trusty diesels, refuse to stay in 18" curves (as my BLI J1e does). Doesn't make for a very happy first experience with a stream loco. I changed to 22" radii, and the Hudson chuffs right around them.

Just food for thought.

[selector]

May I add my two-cents worth? Why are you leaning towards 18"? Is space a problem, or must you use them for economic reasons?

I am relatively new to this hobby, but I have completed a substantial layout, and have done a fair bit of late-night reading, both in magazines and here. The concensus is that you should always try for the biggest radius you can manage. Firstly, assuming you are failry meticulous about laying track (and fairly adept), all rolling stock that is not properly weghted tens to hop out of the tighter curves. Many larger steam locos will, as well. I'm not familiar with diesels, but they don't have rigid, or fixed, sets of large drivers, so I accept that most will have no problem on 18" radius. However, getting back to the conensus, virtually everyone urges the asker to get larger radii because they look much better, and reduce the toy-like appearance a fair bit. The layout looks more realistic.

Having said all of this, my recommendation to you is this: go with what works and with what you can afford. Get the layout bulit, but don't lay the track too permanently, and see what develops. If you decide that the 18" radius is not very appealing, it should be simple to replan, take out the curves, and install wider ones as you see fit.

Have fun, no matter what.

Cheers.

[Anonymous]

I usually refer back to the annual February MR product index, Product reviews, Diesel/Steam, then to the specific year/month for that particular loco.
In Rob's case he may not have the last few years. I'm sure any one of us
can help you out with those specifics once you know what model. Some three axles will work and also some steamers, but not the 85' passenger cars

WELCOME ABOARD!

[Fergmiester]

QUOTE: Originally posted by IRONROOSTER

QUOTE: Originally posted by twhite

Well, just goes to show you what time-frame I'M in!! I thought you meant a 4-8-0 steamer, and I was going to say that the pilot wheels would probably derail. Okay--back to the drawing board.
Tom [:I][:I]

Don't feel bad, I thought he was talking about a 4-12-2. I was going to say no way.
Oh well.

Enjoy
Paul

Oh Good, Great minds do think alike!

Tom: You'll be happy to know that 2 axle pilots will easily negotiate 18" curves. The Allegheny's trailing truck, which is 3 axle, has no issues with 18" curves.

Rob: from what I understand each manufacturer has different tolerances. So your best bet is to look up their website and check out the specs if they have them.

Fergie

[IRONROOSTER]

QUOTE: Originally posted by twhite

Well, just goes to show you what time-frame I'M in!! I thought you meant a 4-8-0 steamer, and I was going to say that the pilot wheels would probably derail. Okay--back to the drawing board.
Tom [:I][:I]

Don't feel bad, I thought he was talking about a 4-12-2. I was going to say no way.
Oh well.

Enjoy
Paul

[trainfan1221]

You`d be amazed what can fit around those tight curves, but you have to watch for overhang clearance, also larger stuff doesn`t really look too good on them. (Think passenger,intermodal,etc.)

[twhite]

Well, just goes to show you what time-frame I'M in!! I thought you meant a 4-8-0 steamer, and I was going to say that the pilot wheels would probably derail. Okay--back to the drawing board.
Tom [:I][:I]

[CP5415]

The AC4400's & large 6 axle loco you might have problems, but SD40-2 should be no problem.

Gordon

[steveblackledge]

It's going to be very difficult, my minimum on the old layout was 20" and SD's and bigger loco's tended to de rail sometimes, also some of the longer trucks and rolling stock don't like much less than 22" Radius, i would go with four axle units and trucks under 50 scale feet

[Javern]

yes they CAN run on 18"

[rob_c65]

I AM CURRENTLY BUILDING A 4X8 HO LAYOUT UTILIZING 18" RADIUS CURVES. WILL I BE ABLE TO RUN 12 WHEEL LOCOS OK ON THEM? I APPRECIATE ANYONE'S THOUGHTS.