7mm Wheel Standards

[ian@stenochs]

An interesting thread.  Track standards are only part of it.  

 

You can have any gauge for a railway. If built to suit it and as long as the gauge, check gauge, back to back and wheel profiles are matched it will work as a miniature railway.  However when you start to model to a strict scale, 1:43.5 say,  then things are not quite as simple.  If we are modelling a prototype then only by using the exact scale gauge can we build scale models!  Anything else is just a caricature which may capture some of the appearance of the original but it is not a scale model no matter how loud you say it is!  

 

We all can recognise Gerald Scarfes depiction of Maggie Thatcher even with the great elongated nose but no way would you describe it as an accurate depiction. Models tottering along on narrower than scale track are compromised, we may recognise the prototype, like Maggie, but don't tell me that the narrow frames and other compromises aren't seen.  To misquote an advert from the past "the further away the better it looks!". A Hornby Princess Elizabeth can look just like the real thing if it is far away but I like my models to look like the real thing, close up.  Only by modelling to exact scale track standards can that be achieved.

 

Happy modelling,

 

Ian.

 

PS.  Even though I advocate Scale standards I can still recognise the craftsmanship and skills required to model in a compromised gauge.  Indeed if you build from scratch rather than just buy RTR or assemble kits then I think you need more skill to cope with the compromises. 

[Simond]

Ian,

 

It seems you are advocating "zero tolerance", but even the real thing has deviations from the nominal sizes caused by the practical limits of manufacturing capability.

 

32mm track in 0 gauge would be 1392 mm full size. Correct nominal gauge is 1435. Whilst the difference is clearly not within acceptable manufacturing tolerances, I'd challenge anyone to spot the difference from 100' ( less THAN the length of two typical grouping coaches) or more away, even if adjacent tracks were laid to the different gauges. I'd bet the same is true in model form.

 

And I'd bet that just about every finescale 0 gauge modeller would have chosen 33mm gauge if we did not have a legacy of 32mm stock, RTR track & point work to live with. It's the " I wouldn't start from here" scenario.

 

Best

Simon

 

Edit - missing word

[Adrian]

Ian,

 

It seems you are advocating "zero tolerance", but even the real thing has deviations from the nominal sizes caused by the practical limits of manufacturing capability.

 

 

I wouldn't like to presume what Ian is advocating but for me I build to the same tolerances in Scale7 that I did when building in Finescale, it's just the wheels and the chassis are a bit wider apart otherwise it's just the same.

 

As Ian alluded to building in Finescale in some ways is harder than Scale7,  I certainly struggled in fine scale to get everything to fit and look right. With the wheels further apart it meant that I didn't have to cut away the firebox to fit around the wheels, the running plate was the right width because it didn't have to be widened to reach the frames etc. So hat's off to those that can scratch build in fine scale - it was too difficult for me.

[Dava]

I'm sure I'm not the only relatively recent newcomer to gauge 0 to find this confusing: finer scale standards (0MF & 0SF less than 32mm Gauge, a nominal Gauge of 32mm, and Sevenscale and the 'correct' Gauge greater at 33mm or whatever).

 

I see that 32mm is wider than it needs to be on straight track with FS wheels, where 31.5 would run more truly. Some commentators above have confused scale and Gauge. Even 7mm/foot which we use as rule of thumb and 1:43.5 or whatever are different and would give a Gauge variation of 0.3mm if adopted to set the Gauge. 4'8.5" is 32.6mm at 7mm/foot, but 32.9 at 1:43.5. Not much but they're not identical.

 

Most of us are going to stick with the new RTR loco wheel and Slaters wheel standards and Peco track standards because we don't want to or cannot change or turn wheels and don't build our own track. I realize it's all a compromise but was it too much to expect the G0G, which has technical committees with clever guys and been around for yonx, to have sorted out a workable set of standards for manufacturers to use?

 

Dava

[jim.snowdon]

Dava,

 

It isn't, and I drafted a revised standard that set everything out correctly ages ago. To be polite, the Guild Technical Committee would appear to be, simply, sitting on it. Either it's too difficult for them or it has challenged something sacred. The wheel standards are those which the bulk of the suppliers already use for 0-Finescale, and the workable gauge of 31.5mm has been adopted by a growing number of modellers, with success.

 

Jim

[ian@stenochs]

Hi Simon,

 

Of course there have to be tolerances and some compromises,  We are after all trying to reproduce a miniature of the real thing and some things just don't scale exactly.  I am advocating working to the scale for everything possible.  The track gauge is the major one where by using a gauge which is not the same as the scale gauge everything to do with the wheels and motion gets put out of place.  To choose 32mm for 1-43.5scale,  with its agreed standards and coarser wheels, tighter back to back etc forces the frames on steam locos to be much less than scale. This forces the foot plates/running boards to be made wider than scale to meet the frames. Where the frames rise above the footplate they have to be spaced out at scale distance otherwise the smokebox saddle will have to be squashed to fit.  Where outside cylinders and motion are concerned the brackets etc have to be lengthened to bring the cylinders to the correct distance apart. Because the wheels are also out of scale, by being too thick and having larger than scale flanges, this forces the motion even further out to give working clearances.  The larger than scale flanges leaves less space between them and force compromise in fitting brakes, Some kit designers stretch the wheelbase and thus alter proportions just to accommodate the errors the gauge standards force thus increasing still the lack of fidelity to the prototype.    There are compromises required in the track as well, you can make a perfectly operating point to any standard but it will NOT be a scale model unless you use the correct scale gauge and other dimensions 

 

What I am advocating is using the correct scale for everything one can.  Only the true scales, 2mm, P4, S and S7 let you do that.  The others, N, 00, EM,O are all compromised to a greater or lesser extent and models built to them are, as I described them, Caricatures. I will agree that there are some very good ones and almost all can be recognised as a representation of the actual prototype but not all stand the close up test!

 

I will admit that it is a minority of the railway modelling public who agree with my stance, most are happy to make a model railway which looks OK and in most cases it does and they are happy. I have many friends who do just that and I respect that.  I too can enjoy operating and running a railway no matter what the standards, imagination can hide a lot of compromise but in my own personal modelling I prefer proper scale and I know that the same friends respect my position. 

 

Ian,


 

 

 

[jim.snowdon]

Ian,

 

It is a benefit of the free world that you can advocate working to dead scale, and whilst it does resolve some of the issues that are inherent in a less than scale gauge, I would contest some of what you say. True, the backs of the wheels, and hence the frames are closer together than they should be, which can result on the wheels impinging upon the boiler, although the designers of some kits make matters even worse by imposing additional reductions in frame spacing to accommodate flanged bushes for axle bearings, as well as the tolerance required for sideplay (which needs to be greater than scale in any case to cope with underscale curves). The deeper flanges (although not by much) can indeed cause problems for accommodating the brakes, but then so can the need to maintain electrical clearance where the prototype could let things rub. However, because Finescale wheels are thicker than scale, the motion doesn't move to the same extent as the backs of the wheels. What does cause it to move out is the need to provide greater than scale clearances behind crossheads, for example, or between components such as the expansion link and the connecting rod to allow for the fact that non-scaleable tolerances in the motion make it more floppy than the prototype.

 

We can, thankfully, all agree to differ, but I am not sure I would go so far as to label anything non-scale as a caricature; that is, perhaps, an exaggeration.

 

Jim

 

ps. I don't look at our 7mm layout with a magnifying glass!

[Guest Isambarduk]

"as well as the tolerance required for sideplay (which needs to be greater than scale in any case to cope with underscale curves). "

 

In 0 gauge Fine Standard, most four- and six-coupled locomotives do not need any sideplay in their axles because there is so much 'slop' between rail and wheel flanges to take up the tollerance down to 6' radius, at least; all that is needed is minimal end-float to allow hornblocks to raise and fall without jamming.

 

David

[jim.snowdon]

"as well as the tolerance required for sideplay (which needs to be greater than scale in any case to cope with underscale curves). "

 

In 0 gauge Fine Standard, most four- and six-coupled locomotives do not need any sideplay in their axles because there is so much 'slop' between rail and wheel flanges to take up the tollerance down to 6' radius, at least; all that is needed is minimal end-float to allow hornblocks to raise and fall without jamming.

 

David

But rather less if you work with 31.5mm or tighter track, and next to none for S7.

 

Jim

[Simond]

Ian,

 

I have to agree with Jim, "caricature" is rather too harsh IMO!

 

Otherwise, I suspect we are all, pretty much in agreement

 

Best

Simon

[Guest Isambarduk]

"But rather less if you work with 31.5mm or tighter track, and next to none for S7."

I agree, Jim.  Nevertheless, the way to accommodate tight curves in the model is the same as in the prototype: gauge widening; slop or excessive side play in the axles is not the way to go no matter which standard you adhere to.  Wouldn't you agree?

 

David

[ian@stenochs]

Simon, Jim,

 

I think you both understand what I am getting at and caricature certainly describes the Hornby Princess and the more modern products of the likes of Ace Trains.

Perhaps 'Oil Painting' is a better description of a semi scale model. Looks the part from a distance but the closer you get you see all the brush strokes.

 

Ian

[jim.snowdon]

Ian,

 

I take your point, but then I wouldn't call them representative of fine scale either.

 

Jim

[keidal]

Just a thought - is there anyone or a company that can convert Slater's Fine Scale loco wheels to Scale Seven standards please, without involving Gauge O Guild membership ? Thank you,

Keith

[daifly]

I get mine turned by Colin Dowling. Contact via http://www.eastsidepilot.com

 

Colin will modify the profile, thin the wheels, chemically blacken - whatever you, the customer, require. No connection other than as another S7 member and customer.

 

Cheers

 

Dave

[Simond]

I've never done it, but I'd expect it to be entirely possible. I think there was a thread on here, or WT on the subject. You will, of course, need to purchase a set of S7 axles. You might well have to pay someone to do the turning, unless you're lucky enough to have a local model engineering society who will let you use their lathe.

 

Not entirely sure it makes sense to do so - if the wheels are new and unused, then I'd try to swap them at Slaters, if not, I think you'd be better trying to sell them on a suitable model website and buying new wheels & axles to S7 standards - I think it would probably not cost any more to do that than to modify the wheels you have.

 

HTH

Simon

 

Edit - Dave beat me to it. It obviously is possible!

[daifly]

Keith

 

If you are interested in modelling in S7 then I urge you to join the ScaleSeven Group. Information here.

 

Slater's make a number of popular locomotive and tender wheel types to S7 standards but they are ONLY available from the ScaleSeven Group. Slater's sell to everyone their S7 axles, wagon and coach wheels plus a number of broad gauge locomotive wheels. 

 

Cheers, Dave