Outside width of S7 Terrier Wheels

[PaulR]

Hi All,

If anyone has a terrier in S7 (a converted Dapol one perhaps), I'd be really grateful if you could measure the outside dimensions of Slaters wheels plus axle? I have an old Roxey whitemetal one and I want to see if it would be possible to widen the space underneath by filing out the metal on the inside of the body. The centre wheels have plenty of space, but the front and rear ones are quite close in FS 7mm.

I'm assuming that, although the gauge is wider by 1mm, because the wheels are a finer profile, the difference may actually be minimal. I'm quite new to S7 and I haven't worked this relationship out yet.

Many thanks,

Paul

 

[Eastsidepilot]

The problem with Slater's wheels is that the tyre width on their loco driving wheels is way over scale, as much as 3.95mm om some, when I have re-profiled them for S7 I turn the back face off by 0.3 mm, this reduces the tyre width, not enough for scale width, but at the same time leaves enough on the flange for the profiling tool to create a new flange with out reducing the diameter to much.
Ideally in S7 you are looking at 2 x 3.25 mm ( wheel tyres) plus 31.25 back to back which equals 37.75 mm o/a the wheel set, this would be a minimum.
A reprofiled Slaters wheel is going to be 2 x 3.6 mm + 31.25 mm = 38.45 mm. o/a.
You may be able to squeeze a bit more off the tyre widths by taking some material off the outside faces of the tyres but you wont get a lot.
If you go for cast wheels then you can turn them to dead scale widths.
I have never understood why Slaters make their pony/bogie and tender tyres thinner than the drivers ? these come in at around 3.45mm width which means you can get them down to scale width easily but alas not the drivers ! Surely they should be all the same tyre width ?
You can reprofile the Dapol wheel sets to an accurate width as they are finer than Slaters.

Col.

 

[Overseer]

I have never understood why Slaters make their pony/bogie and tender tyres thinner than the drivers ? these come in at around 3.45mm width which means you can get them down to scale width easily but alas not the drivers ! Surely they should be all the same tyre width ?

In the US yes, in the UK no. US practice is to use 5 1/2 inch wide tyres on all loco wheels and rolling stock (with a 1” wide flange). UK rolling stock has 5” wide tyres. Steam locos usually have 5” wide carrying wheels and wider driving wheel tyres, often 6” and sometimes wider, hence the variation in Slaters wheels - although being finescale they are wider than scale.

 

[PaulR]

Thank you Colin, that is a very clear explanation which makes a lot of sense. As a newcomer to S7 I've only been aware of Slaters drivers up to now, which you kindly turned down for me. The terrier has a 40mm space underneath but it should be possible to take nearly 1mm off each side and hopefully that will be enough. However, this loco is a long way down the list and I have three other locos to convert before that - thankfully two are etched brass with plenty of space.

As to Scaleseven, I'm really enjoying the journey. I've been all round the houses with deciding what to do after Old Parrock (scale, gauge, theme etc) and finally decided that I must choose one thing and stick to it! If all goes well I'm within a month of completing my first loco conversion.

 

[Ian@StEnochs]

The problem with Slater's wheels is that the tyre width on their loco driving wheels is way over scale, as much as 3.95mm om some, when I have re-profiled them for S7 I turn the back face off by 0.3 mm, this reduces the tyre width, not enough for scale width, but at the same time leaves enough on the flange for the profiling tool to create a new flange with out reducing the diameter to much.
Ideally in S7 you are looking at 2 x 3.25 mm ( wheel tyres) plus 31.25 back to back which equals 37.75 mm o/a the wheel set, this would be a minimum.
A reprofiled Slaters wheel is going to be 2 x 3.6 mm + 31.25 mm = 38.45 mm. o/a.
You may be able to squeeze a bit more off the tyre widths by taking some material off the outside faces of the tyres but you wont get a lot.
If you go for cast wheels then you can turn them to dead scale widths.
I have never understood why Slaters make their pony/bogie and tender tyres thinner than the drivers ? these come in at around 3.45mm width which means you can get them down to scale width easily but alas not the drivers ! Surely they should be all the same tyre width ?
You can reprofile the Dapol wheel sets to an accurate width as they are finer than Slaters.

Col.

I can get a Slater driving wheel tyre down to 3.4mm thick by taking a bit more off the front but then I am working for myself and bear full responsibility, and cost, if I wreck the wheel. The front internal flange on the tyre is about 0.38 thick, difficult to measure with a moulded centre in place.

Worth remembering that for S7 we don’t need to have much more than running clearances, no need to allow a lot of sideplay especially on short wheelbase engines.

Ian.

 

[Eastsidepilot]

To make life easier with clearances on an 0-6-0 you could probably reduce the side play on the leading axle down to a minimum, increase it on the centre axle and I'm assuming the motor drives the rear axle so no side play, although having said that depending on how the motor/gearbox is mounted I have built chassis with some minimum side play on the rive axle which worked ok.
Of coarse you will need to joint the rods so that there is some flex.

Col.