0 gauge fine-scale on tight radius curves

[brossard]

3 minutes ago, F-UnitMad said:

I did that for a curved switch (turnout, point, etc!) that I needed in O with 4ft outer radius & 3ft inner. There were no O templates with those radii, but enlarging the Peco OO (setrack, I think) curved point template worked a treat.

This photo was taken while ballasting it. Of course it's for American O; with buckeye couplers & no buffers, curves can be much tighter than for UK O, & still use long locos & stock.

AFAIK, for long British stock minimum radius is 6ft really. Even auto-couplers can't take long stock through much tighter curves; they are not really a direct equivalent of the 4mm tension-lock coupler.

 

Good to know.  Sometimes I think I'm a voice crying out in the wilderness.

 

I started building a sort of horseshoe shape in the basement where the narrow part was 11' wide. 

 

 

 I did actually build the basic trackwork and ended up with something like 4'6" radius.

 

 

Tests on that showed that all my locos (6 coupled tanks like Terrier and Jinty) pulled wagons well enough and even propelled OK, but I could see the buffers hanging on by a fingernail.  My friend's G5 came to grief when propelling bunker first because of the large overhang.

 

All that got abandoned in favour of the current BLT where curves aren't an issue.

 

John

[Nearholmer]

The ancient solution for those wishing to use 3-links on sharp curves with abrupt transitions is to adopt wide buffers, as marketed by a Leeds Model Company from the 1920s (possibly earlier) for that very application. I always find it a minor miracle when I back stock with those buffers through a crossover and they all behave nicely.

[New Haven Neil]

#cough# drawing pin heads..... ;-)

[New Haven Neil]

😉

Set track points with diverging roads shortened.

 

[Donw]

The problem with crossover is you end up with an S curve which doubles the buffer locking problems .  If you build your own turnouts you can have the diverging route straight from the crossing nose  and with a bit of extra between the tracks you can have a short bit of straight which if it is a wagon length makes a lot of difference. Neil idea of cutting back the settrack turnouts does the same thing. Having a wider gap between parallel tracks also helps by bringing the fouling point closer to the turnout. I think it was Mike Vincent who put some  info on that in one of the small layout books. Long coaches a always an issue with sharp crossovers.  I find you can usually avoid them as the coaches usually are just run into a platform and back out after the loco has run round. If you cannot keep the passenger line either straight or gentler curves Yv points give a gentler diverging route in the same space. A a short single coach length of a larger curve before the main tighter radius acts as a transition because it reduces the mis alignment which is at a maximum when one coach is wholly on the straight attached to one wholly on the curve.

 

Don

[Nearholmer]

Two pre-war wagons fitted with Leeds buffers doing the shimmy over a rather horrible 38” to 24” reverse curve. I can shunt an entire string of these through here without tears, and the turnout has a curved crossing.

 

The buffer faces are way over sale width, being a sort of elliptical shape, but I would suggest this is a small price to pay for shuntability.

[F-UnitMad]

2 hours ago, New Haven Neil said:

😉

Set track points with diverging roads shortened.

 

Yes, short(ish) locos & short 4-wheel stock will go through radii as sharp as 36" - I even got Heljan 'modern' air-brake stock to take that curve. The issue is with long locos & stock. I probably posted these already, but maybe worth repeating....

On 36" radius curve - HJ 37 with 4-wheel van. Buffers waaaay out of line.

 

HJ 31 & 37 on 36" radius. Ignoring the buffer locking that would have occured as they entered the curve, even though the nearest buffers are now in line, the couplings would need to be about a 5- or 6-link to couple them together!!!

 

[Fastdax]

What's the chance that a 9F will go round a 4 foot radius curve?

 

Caveats:

- DJH 9F kit (unbuilt) so things like axle sideplay, pony clearance etc. can be adjusted to suit

- Test track only, so if some items of rolling stock don't go though, fine

- Test track only, so no propelling of stock

- O gauge finescale using Peco bullhead track

 

I have a 10 foot square room and I'm thinking of running a single-line test track round the walls (maybe with a passing loop accessed through Peco medium radius (6 foot radius) turnouts). I want to keep the curves to 4 foot to minimise the real estate taken up by each corner.

 

Thoughts?

Edited December 29, 2023 by Fastdax
Edited to say 4 foot radius

[Nearholmer]

Well, the Ace Trains coarse-scale 9F goes round 2ft radius (and looks very strange while doing so), so it can be done by incorporating lots of side-play. The flange-depth isn’t really that decisive. Maybe you should have s look at one, of have a chat with Len Mills who designed it. Lots of close-up photos of one here https://thestationmastersrooms.co.uk/catalogue/product-details.aspx?id=T40525&t=Ace+Trains+O+Gauge+E28%2FD1+BR+9F+Loco+%26+Tender+"Unlined+Gloss+Satin+Black"+Pre+56+R%2FN+92079+Electric+2%2F3+Rail+NEW+Bxd

 

 

[kernowtim]

I did try to run my Ace 9f on Hornby  tinplate 2ft radius track, it wasn't keen and the valve gear jammed up when a crankpin fouled part of the valve gear!

A lot of American O gauge is designed to run on 36 inch Diameter curves and some on 27 inch, not what we would call finescale though! 

I have seen Heljan cls 45 run  on peco sm32 set track curves, 2 ft 6 radius. 

[Nearholmer]

I’ve not actually got any 24” radius, but a friend tried his two 9F round the 27” radius on my old layout, and they worked fine, although, as I say, looked pretty peculiar doing so.

[Fastdax]

3 hours ago, Nearholmer said:

Well, the Ace Trains coarse-scale 9F goes round 2ft radius (and looks very strange while doing so), so it can be done by incorporating lots of side-play. The flange-depth isn’t really that decisive. Maybe you should have s look at one, of have a chat with Len Mills who designed it. Lots of close-up photos of one here https://thestationmastersrooms.co.uk/catalogue/product-details.aspx?id=T40525&t=Ace+Trains+O+Gauge+E28%2FD1+BR+9F+Loco+%26+Tender+"Unlined+Gloss+Satin+Black"+Pre+56+R%2FN+92079+Electric+2%2F3+Rail+NEW+Bxd

 

 

I should have made it clear that I'm talking about 4 foot RADIUS, not diameter. Apologies for being ambiguous.

[Nearholmer]

You weren’t ambiguous; my thinking was that if one can be got round 2ft radius, then a study of how that was done might inform getting one round 4ft radius.

[F-UnitMad]

6 hours ago, kernowtim said:

A lot of American O gauge is designed to run on 36 inch Diameter curves and some on 27 inch, not what we would call finescale though! 

In American O terms, "O Gauge" means 3-rail. "O Scale" means 2-rail, 'finescale', and most diesels & rolling stock are designed for 36" minimum radius. And it doesn't look that bad either; here on my layout (unfinished) a "Dash-8" & train comes off a 36" curve on to a #6 switch (approx to a 6ft radius point)

Of course buckeye couplers & no buffers help no end with tight radii..!!

 

I have no idea how 2-rail US O steam locos fare on tight curves, especially longer wheelbase, non-articulated types, so I can't comment on whether a 9F could take a 4ft radius curve or not.

[Hal Nail]

13 hours ago, Fastdax said:

DJH 9F kit (unbuilt) so things like axle sideplay, pony clearance etc. can be adjusted to suit

I don't think I'd compromise the build just for a test track, personally.

[Donw]

 The 9F have a flangeless centre driver if you replicate this it will help with tight curves.  The biggest issue might be the drawbar between the loco and tender you may need a longer one. Especially if you use have the loco and tender picking up from opposite rails. 

 

I have a Tower models King which will  cope with less than 4 ft radii but looks like a dog with its togue hanging out the bogie is so far from the body.

 

Don

[Fastdax]

1 hour ago, Donw said:

 like a dog with its togue hanging out

 

[Fastdax]

1 hour ago, Hal Nail said:

I don't think I'd compromise the build just for a test track, personally.

 

I'd only compromise the build in ways which didn't affect its performance or appearance on normal radius curves. A little extra side-play should be OK and can always be removed with extra washers if necessary.

[Nearholmer]

Brake gear will be an issue. Most coarse-scale models are completely devoid of it, because it gets in the way of the side play of the wheels.

 

One thing I think Len designed into the Ace one is a very shallo radius on the tread of the un-flanged wheels, and I think the flanges on the second and fourth wheel-sets are vestigial by coarse standards to give a tiny bit more wriggle room. You might not have to go to that extent though.

[goldfish]

On 29/12/2023 at 18:35, Fastdax said:

What's the chance that a 9F will go round a 4 foot radius curve?

 

Getting a fine scale 2-10-0 around 4' radius curves is achievable, Lenz get their Class BR50 2-10-0 around 3' curves with flanges on all ten driving wheels. Whether it is achievable with a kit designed for a minimum radius of 72" depends on how many compromises you are prepared to accept, A little school boy maths suggests that you would have to provided a minimum of 1.8mm extra side play* between the outer and inner flanged wheels. This will necessitate modifying the valve gear to allow additional sideways movement and the varying distance between the flanged wheels. The unflanged centre wheel could be a problem on 4' points by fouling the frog and so may need to have its vertical travel limited. The chassis of the 9F is very exposed and any modifications would be hard to disguise, so the end result might not be visually pleasing. How many compromises you are prepared to accept?

 

* Just to clarify, the additional play is required both sides of the centreline, with possible implications for clearance between the backs of the wheels and the frames.

Edited December 31, 2023 by goldfish
Added footnote.

[sncf231e]

11 hours ago, Nearholmer said:

Brake gear will be an issue. Most coarse-scale models are completely devoid of it, because it gets in the way of the side play of the wheels.

 

ACE trains are devoid of brake gear (Allen Levy does not like it), but I wonder whether most coarse scale models are devoid of it (I did not make a count). Most US coarse scale models, and these are made in large quantities, do have it.

Regards

Fred

[Nearholmer]

Beg pardon: I was thinking of British made or commissioned models.

[hartleymartin]

I recently ran some 1970s Vintage Atlas O gauge, which has 24" radius curves and points. Much to my surprise, British four-wheelers ran quite happily around these curves, hauled by locos such as the Atlas Plymouth 0-6-0 shunter, Heljan 03, Dapol Sentinel, Rivarossi DB Class 89 (0-6-0), and my Ixion Manning Wardle H Class. It helps if the buffers and couplings are sprung, but not 100% essential. I also have some 36" radius curves, which I might set up later. My Ixion Hudswell Clarke struggles a bit on 36" radius. It largely depends on your choice of prototype, and whether or not the model is made to allow for sharp curves.