HO compared to OO

[mjb1961]

Hi, I know HO will run on OO and vice versa but the size comparison is it really noticeable,IE HO scotsman-OO scotsman, your thoughts really appreciated.

[Topcat1707821625]

If you are talking about running HO and OO trains together on an OO layout then yes, the size difference is very noticeable. Also remember that the bodies of OO rolling stock are over scale for the gauge, so you will have the following problems:

1. Track spacing has to be greater for OO than HO, so the distance between HO trains on parallel tracks will look wrong.
2. Platform clearances need to be greater for OO, so when you run HO rolling stock there will be big gaps between the train and the platform.

Conversely, if your layout is designed for HO and you try to run OO trains then they may collide with each other and with platforms owing to the smaller track spacing and platform clearances..

[threelink]

HO and OO are 2 different scales. OO is 4mm to the foot and HO is 3.5mm to the foot. The track is the same gauge. In HO it is correct. In OO it is under gauge. OO was adopted by British manufacturers long ago because of the difficulty of squeezing the mechanisms then available into British outline locos (smaller than their continental and USA counterparts). A British outline loco at 4mm to the foot (OO) would accommodate the mechanisms but at 3.5mm (HO) it would not. In a cost saving exercise, HO track was used for OO locos and stock. An HO Flying Scot will be smaller than an OO Flying Scot. Just to confuse the issue, Trix introduced some locos and stock at about 3.8mm to the foot, the intention being that they would be compatible with either scale but in fact they were compatible with neither being over sized in HO and under sized in OO.

[mjb1961]

Thankyou both for your replies,,,I had pre ordered the Trix/Marklin Flying Scotsman advertised with Rails of Sheffield not thinking that the scale difference would be that noticeable,majority of my stock is hornby oo gauge and I can visualise my oo gauge teaks on the back of the ho scotty,i have now cancelled that pre order ,,,,thankyou Martin.

[Yelrow]

Gosh, that was an expensive loco. I would want a new mower for that price. Nice though.

[ntpntpntp]

The scale difference between OO and HO is similar to the difference between British N and European N. It is noticeable when you put the models next to each other, not so bad if you use just one or the other scale in a train.

Top to bottom here are some models of the class 66 diesel in different scales:

Hornby OO

Mehano HO

Dapol British N

Kato European N

[threelink]

@ntp

Please forgive my ignorance, but I am not an N scale modeller. Why is there a difference between European N and British N? Is it because British N is half OO and European N is half HO (or vice versa)? I always thought that N was 2mm to the foot and would have expected manufacturers of N scale products to model them @ 2mm to the foot irrespective of the country of manufacture - or am I being overly simplistic?

[ellocoloco]

British N is 1/148, European and US N is 1/160. Basically the same compromise as with OO and HO. An increased body scale to compensate for the smaller UK load gauge.

[ellocoloco]

You've got to love the 66. An easy way to get accurate modern outline British models. I've got the Trix Scottie on order as well, I'll worry about what to run with it later.

ESU and Hornby (Everyone needs a Capt Tom.)

Depending on what stock you are running they don't look too bad, but its still a bit wrong.

Lima and Athearn.

[ntpntpntp]

@threelink as @ellocoloco says the difference in N scales (1:148 .v. 1:160) was originally down to fitting motors into small British loading gauge locos. As with OO, British N models are technically running on track that's too narrow for the scale and they do look a bit top-heavy when viewed end-on.

"2mm to the foot" is actually neither 1:148 not 1:160 but is a useful approximation. There is of course a community of modellers who do work to 2mm (1:152) with fine scale correctly gauged track etc.

[Rana Temporia]

While a lot of the older continental HO locos were to scale, the same couldn’t be said for the rolling stock and many of the coaches while correct in cross section were lengthwise to a scale of 1/100 so were shorter than they should be. Some were even shorter than that, for example some of the LIma Pullman coaches.

HO look much better and to scale, just as the modern TT does when compared to the old 4’ scale gauge of the 1960s stock. However, I know which I would really prefer!

[81F]

I actually bought a LIMA HO scale class 33 to pull my jouef HO CIWL sleeping cars since my 00 locos looked so odd. However did anyone ever make a MK1 BSK in HO in BR blue/grey?

[Rana Temporia]

81F, Jouef made HO Mk1s in blue/grey under the Playcraft name but they were too short and had solid lumps of plastic to represent the buffers. For some odd reason the blue/grey ones I have don’t have numbers while all the other versions in green, maroon and western region colours do. However, they do have the yellow stripe for 1st class and the red stripe for the restaurant car. I think their version is a BSO rather than BSK, I will have a look later.

I think the Lima HO MK1s were scale length but I have never seen one in blue/grey.

[Peter Stiles]

Personally I feel you'll be disappointed in the size of the HO Flying Scotsman.

The HO model is quoted at 245mm and the Hornby OO as 291mm. That's five centimetres of difference in length. add some OO coaches behind it and it may seem a little out of kilt..

[threelink]

Thankyou all. My modelling education continues. I had not realised that the difference between European N and British N was down to the same reasons for the difference between HO and OO.

[Rana Temporia]

These were the blue/grey coaches in the Playcraft range. It was a BSK that they did. A shame these coaches were shorter than scale length as they run so well. Some people have used them to make HO DMU/EMUs. They did the SO which Tri-ang/Hornby didn’t and would have been the best coach to make a number of EMU/DMU units from in OO.