Hello,

I am about to build a first and simple n gauge layout. Straights with semi circles at each end. My largest semi circle measures max 29" diameter (R=14.5") and I would like another track to run inside this.

I was initially a bit confused about the Rad 4, 3 etc terminology but I have found:
Rad 4 in N is 333.4mm ( 13 1/8 inches)
Rad 3 in N is 298.5mm (11 3/4 inches)
Rad 2 is 263.5mm (10 ⅜)
Rad 1 in N is 228mm (9 inches)

My outer radius is 14.5" or 370mm, inner 13.5 or 350mm but I would like to ask/double check, to achieve a curve at each end of my layout, semi circle at each end, would Rad 4 be correct? i.e 2 lots of Rad 4 with the outer track having a straight 'spacer' in it (the outer semi). 

thank you

Rad 4 = ST-19

If you are using only the pre-formed "set track", pieces to make a double track, the usual is for the inner track to be one radius less than the outer, so for example R3 for the inner & R4 outer track. If you have space for more generous curves larger than R4 there is the option of Flexitrack which can be bent to any radius desired.

In the space you have, you could either use R3 & R4 (a short straight in the middle optional, but if you do, you should put the same length in both the inner and outer track), or you could use R4 for the inner track and flexitrack to form the outer line.

Hi pgtips, and welcome to the forum
Now then, it's Sunday and I seem particularly dense today but if radius 4 = 333.4mm how can your outer oval curves be 370mm? Have you made them using flexitrack rather than fixed radius curved pieces? If you made your outer oval from ST-19 radius 4 curves I don't see why you'd need a straight 'spacer'. Just use radius 3 curves for the inner oval, as I think points are made to reflect that geometry.

edit - attached please find a diagram using ST-19 outer oval and ST-17 inner

As @Newportnobby  asks, how are you planning to achieve your two radii if they are outside of the available Peco Setrack range? Are you using flexi track or are you using a different brand of sectional track perhaps?

[edit] Ah I see you propose using R4 for both lines with spacer straights?  No that wouldn't give you nice parallel lines around the curve, it'll look odd. [/edit]

If you're using flexi track then my recommendation would be to use the Peco track centering spacer on it's wider Setrack spacing, remember on curves you have to be sure you leave enough space for coach overhang (centre of the coach on the inside of the curve and end of the coach on the outside of the curve).


You could lay the inside track with R4 and use the Peco spacing tool to guide flexi track round the outside. Buy a bunch of the spacers, they are cheap 

Alternatively, for a beginner I'd be more inclined to recommend keeping things simple and using Peco R4 and R3 for your curves so you don't have to fight with bending/cutting/joining flexi track.  Ok so the two radii are a little less than your original plan, but avoids the requirement for a swear-box       

I've been using flexi track since the 70s, but I still prefer to use sectional curves for long runs such as hidden loops etc.

Hello,

thank you for your replies.
Asked how I could fit "if radius 4 = 333.4mm how can your outer oval curves be 370mm"

I probably was not clear, I have enough space for R = 370mm so diameter of 740mm whereas R4 is less than this, 333 leaving me 33mm spare.
My logic was to add a spacer to the outer semi circle, so to use R4 for both inner and outer, making the outer ring a bit wider.

but I think from replies perhaps I should be thinking R4 for outer and R3 for inner (would ST19 and ST16 be correct ?)
(ntpntpntp you are spot on, I tried flexi 300 track but wasn't going too well, need simpler approach

Newportnobby : I am also a bit bamboozled by double curves and standard curves. ST18 or ST19, ST17 or 16, its very confusing.
I want to achieve a oval with one track inside the other, nice big curves as possible but I do not know which track I should be ordering (std or double curves).

thank you

@pgtips     

"single" (or "standard") and "double" curves just relates to the angle of curves.  So a standard curve is 22.5 degrees, a double curve is 45 degrees (goes twice as far round the corner  )

The most economical way to create a 180 degree curve is to use the double curves , so 4 doubles. It's also better as you have fewer joints.

R3 standard curve = ST16
R3 double curve = ST17

R4 standard curve = ST18
R4 double curve = ST19

I would recommend you use ST17 and ST19 for sides of the ovals.

My preference is not to have a tight curve but the trade off seems to be more joints so I will go for the ST17 and 19 as you mentioned, thank you.

@pgtips  I don't quite understand what you've said there?  There's no "trade-off" more joints for a wider curve. 

R4 ST18 and ST19 are the same radius  It's just that if you used standard curves ST18 you'd need twice as many pieces to get round 180 degrees in exactly the same radius as you would with ST19.   Costs more and has more joints       Same with R3 ST16 and ST17.

Arghh, of course, I see I just mis read it on my phone but yes, it's clear. 
correct track ordered :-)
Thank you again

Quote from: pgtips on April 26, 2020, 02:25:26 PM

I probably was not clear, I have enough space for R = 370mm so diameter of 740mm whereas R4 is less than this, 333 leaving me 33mm spare.

33mm between 2 baseboard edges and track is only 16.5mm per side which is still perilously close to the edge. As many on the forum know, this is one of my pet concerns but if folks want to take the risk of their prized stock plummeting who am I to argue?

Hello/good morning.

My baseboard is 810mm wide at its narrowest, 1220mm at its widest. I'd already allowed for some comfortable edge/scenic edge so I think I said I can comfortably fit 740 diameter.
With R4 its only 333mm (666 diameter) but Newportnobby makes a good point to consider.

My original plan had been to use R4 twice, extending the outer semi but there is no need to complicate it, ntpntpntp and others got it spot on, keep it simple. I am looking forward to the space to build a town etc.

I had attempted to use flexitrack but soon found thats not as straightforward a solution as I wanted, great for straights but not for circles etc.

I had n gauge as a child so like to use it. I bought a layout for my sons birthday last year but I was conned, travelled miles and the guy had a powercut when I arrived. The less said about that the better.

A year later and coronavirus means I have the time to tackle this again in earnest, the layout I bought cannot be repaired so start again I have decided to make something that fits over a desk and could be moved easily. I am stunned at the price of things so I'll be constantly on the lookout for a couple of engines.

Thanks again so far for everyones input and guidance