Tramsitions

[sailor38]

I will soon be building an HO layout starting with, of all things, a 4X8'. It will, necessarily, have 18" radius curves. I don't plan to use anything bigger than a Pacific for motive power. Right now I have a ten wheeler and a four axle diesel and I know they will handle the curves just fine, but I have read that a transition would make things look much better. I will be using flex track for the straight portions. Can someone tell me how to go about making transitions into the curves without my needing an engineering degree to understand it? Later on I may have something as big as a Mike with no blind drivers so I would like it to appear as smooth as possible. Thanks in advance. Youse guys (gals) are all great![bow]

[Big_Boy_4005]

I think for your purposes, a simple 1" offset would do. Instead of going directly from 18" radius to straight, move the straight out 1", then blend the curve to the realigned straight. You could probably do this by eye, or if you had a long piece of stripwood, you could bend it and use it as a guide to mark the curve.

[ndbprr]

A transition is a curve that gets progressively tighter as you travel over it. If you remember a French Curve from drafting class they are all transition curves. So to make it simple the first inch is say 180" radius and the second is 96", 3d= 48", 4th = 36", down to the radius of your main section. if you hold your hand so you are looking at the side of it curve your hand so it is one radius throughout the length. Now just bend your fingertips in a little then bend you knuckles slightly. That's a transition curve when compared to the first one and is more pleasing to the eye.

[j1love]

I believe there is a Kalmbach book on this subject.....may be worh the read. But my advice is this: Follow Big_Boy_4005's advice, BUT...make sure the transition from straight to curve is as long as your longest piece of rolling stock. I cannot remember the name of the book, but it advises that transitions must be as long as your longest car. You mentioned a possibility of expanding later: if you follow this advice you won't have to re-adjust your transitions. I think the term that Kalmbach uses is "easments". Hope this helps you out!!

[cacole]

An easy way to construct layout transitions is with a electricians conduit fi***ape, if you have one of these lying around -- doesn't everybody? If you don't have one, perhaps you can borrow one from a neighbor who has done some remodeling. By pinning the fi***ape in place at each end of a proposed curve and then pulling one end back and forth until it forms itself into the desired curvature, the ends of the tape will automatically form easements.

[stokesda]

There was an excellent (I thought so, at least) and fairly simple visual explanation of how to do this in the July 2004 issue of MR (page 49). If you have access to that issue, I highly recommend checking that out.

Otherwise, go to the main MR magazine homepage (click on the link at the top of the screen) and there will be links to archived articles on the left side of the screen. Click on the one that says "Layout Planning" and there is an article called "Easy Easements." Click on the one that says "Layout Construction" and there is an article called "Laying out an easement with MR templates." Both of these articles are more technical than the first one I mentioned, but they're at least worth a look. Good luck!

Cheers,