Cutting LGB 18000 r5 curves in half for smooth transitions

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mikeabdullah

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Hi there, newcomer to G scale here. Currently experimenting with track layout in my garden for myself and 5 year old son to enjoy mucking about with.

While doing this, I find myself bumping into an area that I thought would be common, but which I struggle to find basically any results for on the Internet. Typical!

I'm aiming for a minimum of LGB radius 3 curves on vast majority of the track, to keep it looking decent and not too tight, and I'm very pleased with the results so far. The spots where I do have R1 points or R2 curves certainly do become sticky running spots quite easily.

I've also got quite a large number of LGB radius 5 curves (18000, 15º) bought for nice gradual curves wherever the space allows it.

To my eye, on the tighter R3 bends, it looks really good to use a short section of R5 as a transition. Supposedly this makes it a little easier for the train to navigate (I'm not sure), and it certainly looks smoother!

Is anyone else out there doing this? I seem to find almost no discussion of transition curves for G scale, particularly specially the use of R5 for the purpose. Maybe all the serious folk go straight to flexitrack for this?

Choppity Chop​

For a transition curve, I particularly like the look of an LGB half R5 piece, 7.5º, product code 18020.

I had initially purchased a couple of these, but I soon wanted more. Then I stared a little closer at all the 15º r5 pieces I've got. They've got a fishplate in the middle of the curve! As best I can tell, the r5 curves are constructed out of 2x 7.5º sections of sleepers, with 15º rails threaded through.

It took some effort, but today I was able to dismantle one, cut the rail in half, and tada I've now got two 7.5º r5 curves, exactly as I wanted, for "free" from leftover full length curves. Very pleased with the result.

Is this a deliberate thing from LGB?? Does anyone else do this? Even more so than the transition curves, I seem unable to find any mention of this on the internet.
 
mikeabdullah said:
Hi there, newcomer to G scale here. Currently experimenting with track layout in my garden for myself and 5 year old son to enjoy mucking about with.

While doing this, I find myself bumping into an area that I thought would be common, but which I struggle to find basically any results for on the Internet. Typical!

I'm aiming for a minimum of LGB radius 3 curves on vast majority of the track, to keep it looking decent and not too tight, and I'm very pleased with the results so far. The spots where I do have R1 points or R2 curves certainly do become sticky running spots quite easily.

I've also got quite a large number of LGB radius 5 curves (18000, 15º) bought for nice gradual curves wherever the space allows it.

To my eye, on the tighter R3 bends, it looks really good to use a short section of R5 as a transition. Supposedly this makes it a little easier for the train to navigate (I'm not sure), and it certainly looks smoother!

Is anyone else out there doing this? I seem to find almost no discussion of transition curves for G scale, particularly specially the use of R5 for the purpose. Maybe all the serious folk go straight to flexitrack for this?

Choppity Chop​

For a transition curve, I particularly like the look of an LGB half R5 piece, 7.5º, product code 18020.

I had initially purchased a couple of these, but I soon wanted more. Then I stared a little closer at all the 15º r5 pieces I've got. They've got a fishplate in the middle of the curve! As best I can tell, the r5 curves are constructed out of 2x 7.5º sections of sleepers, with 15º rails threaded through.

It took some effort, but today I was able to dismantle one, cut the rail in half, and tada I've now got two 7.5º r5 curves, exactly as I wanted, for "free" from leftover full length curves. Very pleased with the result.

Is this a deliberate thing from LGB?? Does anyone else do this? Even more so than the transition curves, I seem unable to find any mention of this on the internet.
Click to expand...

The longer straight track pieces are made up of multiple '1000' track bases as well, so yes, it's a deliberate thing.

Transition curves (also referred to as spiral curves) are used on just about all prototype railways. Approximating a spiral curve through using fixed radius curves of varying radii is hood model practice if you have the space for it.

IMG_2225.png
 
i am indoors with my layout. so i must use even the R1 curves in some places. but for looks and against derailing transitions are better.

mikeabdullah said:
As best I can tell, the r5 curves are constructed out of 2x 7.5º sections of sleepers, ... Is this a deliberate thing from LGB?
Click to expand...

that is deliberate, so that they can use longer pieces of track using the shorter standard sleeper webs( the additional fishplates keep the sleeper webs in place)
depending on the space available i bend between 12"/300mm to 24"/600mm into an "easing" between curve and straight.
and i cut the available track in the lengths, i need.
 
Another way to get your curves transitioned would be to use LGB flex track ( pref 10003 sleepers 10005 rail), though a railbender will help make things more accurate.

Do not decry second hand track whilst you are creating your line, rail will tarnish outside no matter how new unless you get the highly expensive LGB Stainless track.
 
Software Tools said:
The longer straight track pieces are made up of multiple '1000' track bases as well, so yes, it's a deliberate thing.
Click to expand...
Had a closer look and realised why I hadn't twigged this. Some of the older pieces indeed have a proper fishplate in the middle of the straight. I have a number of double straights like this.

But on newer track, of which I've got both double and quad straights, it's a smaller flat piece of metal connecting the sections together, hidden under the rails. Not a full blown fishplate.

My guess is it's great for LGB's manufacturing to share the same sleeper sections among multiple end products, to keep costs down. Likewise probably the switch to using less metal for a hidden connection probably saves costs.
 
Transition curves are very rarely done on model railways, due to space constraints.

Hats off to you for giving it a go Mike....
 
Gizzy said:
Transition curves are very rarely done on model railways, due to space constraints
Click to expand...
This quite surprises me though. On an r3 curve, switching the last 7.5º to r5 adds on ~15 cm, and it seems unlikely one was planning to immediately ram something other than a straight piece in there. But maybe I'm completely wrong :D.

Having said that, I suppose with my current setup, the tightest loop does end where a station is planned to start, so I could gain 15 cm back for station's reversing run around loop. But I aim to get even more out of it later with a Piko curved switch/turnout instead.

I find the gentler curve at start and end here good on the eye. Just need to achieve some actual planting to make it work!
 

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mikeabdullah said:
This quite surprises me though. On an r3 curve, switching the last 7.5º to r5 adds on ~15 cm, and it seems unlikely on was planning to immediately ram something other than a straight piece in there. But maybe I'm completely wrong :D.

Having said that, I suppose with my current setup, the tightest loop does end where a station is planned to start, so I could gain 15 cm back for station's reversing loop. But I aim to get even more out of it later with a Piko curved switch/turnout instead.

I find the gentler curve at start and end here good on the eye. Just need to achieve some actual planting to make it work!
Click to expand...
It will be longer, because although the arc is the same angle, R3 is 4 ft radius and R5 is 8 ft.

Think of a running track where the start line is staggered, so all racers run the same distance to the finish line....
 
Gizzy said:
It will be longer, because although the arc is the same angle, R3 is 4 ft radius and R5 is 8 ft.

Think of a running track where the start line is staggered, so all racers run the same distance to the finish line....
Click to expand...
That doesn't make sense. Here's a picture of a 7.5º r5 piece vs r3 (actually a Piko r5). Just under 15 cm difference in length, to cover the same angle.
 

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Ah, now Piko and LGB geometry are different.

Piko R3 will fit inside LGB R3 and are not the same. The radii are the same for both manufacturers R1 but are then different for the other Rx radii.

I'll try the race track analogy again. The runner on the inside lane of an athletic track covers 400 metre for a complete circuit, but if he ran from the start/finish line in the outside lane, he will run much further, hence the longer the radius then the arc will also increase, the only constant is the arc angle (360 deg for an (elongated circle or oval))....
 
Ignore the LGB/Piko difference; it's a distraction, and besides I clearly stated I'm using a Piko R5 piece for the comparison, which is virtually the same as LGB R3.

Your analogy doesn't hold. Consider two different setups:

A: 8x LGB R3 curves, to give a total of a 180º bend
B: Take those same R3 curves, chop off the last 7.5º from either end, and replace with 2x LGB R5 7.5º pieces

In either case, the vast majority of the curve is the same. It's not like a race track where extra lanes are being added.

The only difference is at the ends of the curve. They're now smoother/softer, and extend for an extra ~15 cm. Therefore this tweak has only "cost" that much at either end.
 
The Claptowte Railway, being U shaped has two 90deg bends. It had been my intention to use 4 x R3 curves, but found that there was insufficient space for this. As a compromise fit, I used R3-R2-half a R2-R3 to tighten up the centre of the curve, making a transitional 90 degree bend. It fits, and still looks acceptable.

David
 
mikeabdullah said:
This quite surprises me though. On an r3 curve, switching the last 7.5º to r5 adds on ~15 cm, and it seems unlikely one was planning to immediately ram something other than a straight piece in there. But maybe I'm completely wrong :D.

Having said that, I suppose with my current setup, the tightest loop does end where a station is planned to start, so I could gain 15 cm back for station's reversing run around loop. But I aim to get even more out of it later with a Piko curved switch/turnout instead.

I find the gentler curve at start and end here good on the eye. Just need to achieve some actual planting to make it work!
Click to expand...
Flexi track can give a transition curve if you don't pre-curve it too much, and if you don't fix it down too frequently.

I much prefer the appearance, and the running characteristics of transition curves, and have frequently mixed 10 ft and 8ft radius curves to achieve this, although now I have quite a lot of second hand flexi as well.
 
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