"Voiding the Warranty" - Mol's experiments in 21mm gauge

[Horsetan]

1 hour ago, Mol_PMB said:

I put this list together mainly of photos of 560 on the Fenit branch, ....

https://www.flickr.com/photos/irishrailwayarchive/53467653382
https://www.flickr.com/photos/irishrailwayarchive/53468560926
https://www.flickr.com/photos/irishrailwayarchive/53468878174
https://www.flickr.com/photos/irishrailwayarchive/53468979775
https://www.flickr.com/photos/irishrailwayarchive/53498929093
https://www.flickr.com/photos/irishrailwayarchive/53499079334
https://www.flickr.com/photos/irishrailwayarchive/53509201430
https://www.flickr.com/photos/irishrailwayarchive/53509204144
https://www.flickr.com/photos/irishrailwayarchive/53511776674
https://www.flickr.com/photos/irishrailwayarchive/53527642129
https://www.flickr.com/photos/irishrailwayarchive/54252114857
https://www.flickr.com/photos/irishrailwayarchive/54418652517
https://www.flickr.com/photos/irishrailwayarchive/54419707054
https://www.flickr.com/photos/irishrailwayarchive/54419902095
https://www.flickr.com/photos/irishrailwayarchive/54419902890
https://www.flickr.com/photos/irishrailwayarchive/54419902915......

Great set of links -  unfortunately the Flickr "irish railway archive" ones are all restricted access.

[Mol_PMB]

4 minutes ago, Horsetan said:

Great set of links -  unfortunately the Flickr "irish railway archive" ones are all restricted access.

...and they are many of the best ones. You need to join the IRRS!

[Mol_PMB]

15 hours ago, Galteemore said:

That’s a great close up. For brass workers like me, it’s also a reassuring proof that platework on the real thing could also be shonky. Check out that front splasher on 655, and as for the gap in the boiler cladding….

Here's 663, the cladding doesn't look too bad on this side but it still looks like it's been dented by some fat fingers and clumsy handling:

But these IRRS photos of the other side show that a whole cladding sheet has come loose and seems to be flapping about:

RNC_MGWR_663_Castlerea_6_Sept_1957 | [Photographer: Robin N … | Flickr

RNC_MGWR_663_Castlerea_6_Sept_1957 (2) | [Photographer: Robi… | Flickr

The loco is still in steam and in use. A few months later it was withdrawn and sat on the scrap line in Athlone with that cladding even more bent out of shape:

AEB_MGWR_663_582_Athlone_16_June_1958 | [Photographer: Antho… | Flickr

What a wreck! 

 

Note that 663 above carried a round-top boiler but had the larger diameter, waisted smokebox normally seen on the Belpaire boilered locos. It's quite a different shape to the almost flat-sided smokeboxes on 654 and 655:

 

[Mol_PMB]

Back to Quartertown Mill, I've been playing with the CAD and laser-cutter to rough out a platform and mill building shape.

I was delighted to find that a local stationers stocks good quality 1.5mm card for a few quid per A1 sheet, which is ideal material for this sort of exercise.

This is truly a job for the lazy man's scalpel!

I'll do similar rough mockups of the other buildings to get a feel for how they look, and if the layout seems balanced. At present I've just estimated dimensions from maps and photos, so there is certainly scope for some tweaks. 

Once I'm happy I can use the rough CAD as a basis for the more detailed and robust structures. 

[Mayner]

On 18/11/2025 at 8:24 PM, Mol_PMB said:

I'm still working on sourcing wheels - I've found some driving wheels but the leading wheelset (and perhaps the tender wheelsets) may need to be secondhand off ebay. And then I need longer square-ended axles; I have some ideas how to do this but need to make a jig first.  

 

Ultrascale wheels are probably the best option if you are able to accept the long lead time (my last order fulfilled within 6mths), supplied to order complete with axle set for 21mm gauge, a decent crankpin system and no risk of tyres coming adrift from the wheel centre unlike AGW driving wheels, Sharman wheels next best alternative if you can source a set (possibly Brassmasters). 

Most of my older 25+year old 21mm gauge steam outline locos fitted with Sharman wheels, Gibson on more recent locos, I ran into a problem with driving wheels coming adrift from the centres during assembly and AGW steel crankpins ringing off. I now remove the tyres from the centre, de-grease,then re-assemble securing with Loctite, I use 14BA c/s bolt as crankpin, AGW crankpin bush and secure with brass 14BA nut, worked without a problem for 25 years!

Most of my 21mm gauge diesels run on Ultrascale wheel sets with b-b set at 19.3. 19.3 B-B works with AGW OO/EM profile wheels,  but 19.5 b-b with Sharman type B wheels which have a narrower tyre width than AGW or Ulrascale OO/EM profile wheels.

I seem to have managed without a wheel quartering jig before buying a GW quartering jig about 20 or so years ago https://www.gw-models.com/product/wheel-press-quartering-jig/  been worthwhile having assembled several locos with press-fit wheels and hopefullyseveral more.

[David Holman]

Swilybegs/Fintonagh, though 7mm scale has always used 4mm finescale clearances, ie 1mm flangeways through the points. My b2b are 19.2mm (ish), which chimes well with what John is saying. The rail is code 82 FB. Have found that anything more than 0.2mm variation in b2b can cause problems.

 Can only echo what he says about Gibson wheels: quality can be mixed. My main issue though has been around drivers coming loose on the axles. Once on, the fewer times you have to remove them during construction the better! Needless to say, a loose driver destroys both b2b and quartering.

 Give me Slaters wheels any day. Square, shouldered axle ends that automatically sort b2b and quartering, plus a strong brass centre too. MUCH simpler.

[Horsetan]

8 hours ago, Mayner said:

....Sharman wheels next best alternative if you can source a set (possibly Brassmasters). ....

What's left of Sharman wheels are available from Phoenix Paints. Stocks are being sold to exhaustion, as the tooling is mostly worn out and Phoenix have no intention of producing more.

[Mol_PMB]

8 hours ago, Mayner said:

Ultrascale wheels are probably the best option if you are able to accept the long lead time 

Many thanks for the advice, John. It's good to know of the pitfalls with certain makes of wheel.

I've had a look at Ultrascale, but their website is currently down and there doesn't even seem to be a way of getting on the waiting list. Even the GW quartering jig is only available on back-order with a considerable lead time! Fortunately, quartering a 4-coupled loco is easier than a 6-coupled one.

1 minute ago, Horsetan said:

What's left of Sharman wheels are available from Phoenix Paints. Stocks are being sold to exhaustion, as the tooling is mostly worn out and Phoenix have no intention of producing more.

Phoenix do seem to have the right sizes, which is a good start. That seems to be the best available option. 

1 hour ago, David Holman said:

Give me Slaters wheels any day. Square, shouldered axle ends that automatically sort b2b and quartering, plus a strong brass centre too. MUCH simpler.

Having spent 20 years modelling in 7mm scale, with the ready availability of Slaters wheels having all those advantages, I have been really surprised to find that in the much more popular 4mm scale, getting hold of decent wheels is such a challenge. I see that Scale Link are retiring in March 2026 and their range of Romford/Markits types is also being run down with many sizes unavailable.

 

The wheel/rail standards I'm working with are 21.0mm gauge, 19.2mm back-to-back, 19mm across checkrail faces. On the wagons and loco I've built so far, I'm using EM profile wheels with a 2.3mm tyre width (compared to 2.8mm on the IRM wagon wheels). This seems to work. 

With a steam loco I've got the old challenge of the overscale tyre width in the splashers. When looking at the wheels available online it's often unclear what the tyre width is. But it looks like the Sharman ones are reasonably fine.

 

Thanks to all for your advice. I'll get there eventually!