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

[Horsetan]

On 17/4/2026 at 5:06 PM, Mol_PMB said:

As per attached spreadsheet.

CSB_calcs.xlsx 21.45 kB · 8 downloads

Interesting. I used a slightly different CSB spreadsheet and tweaked your measurements a touch....

J26_CSB.pdf

[Mol_PMB]

Slow progress today but I’m gradually populating the details.

 

 

 

I need to get some short Ross Pop safety valves for this loco, but can’t find any for sale. Might have to make my own from bits of brass rod, tube and tiny washers. 
I have a couple of sets of Markits tall ones, but I want to save those for the G2 and J15 for which they are correct. 
 

I have a very busy week ahead so there won’t be much modelling time. 

[GSR 800]

Lovely work Mol!

[Tullygrainey]

Very tidy Paul and great attention to detail. Ross pop valves do seem to be hard to come by. I had a small collection pillaged from second hand Hornby 0-4-0 Smokey Joes and the like but I've used them all up now. 

These from A Gibson aren't quite right but might be usable with work though it might be just as easy to make some from scratch as you suggest!

[Mol_PMB]

8 minutes ago, Tullygrainey said:

Very tidy Paul and great attention to detail. Ross pop valves do seem to be hard to come by. I had a small collection pillaged from second hand Hornby 0-4-0 Smokey Joes and the like but I've used them all up now. 

These from A Gibson aren't quite right but might be usable with work though it might be just as easy to make some from scratch as you suggest!

Many thanks, that's a good tip. 557 and 560 had tall Ross Pops, but my prototype 559 had short ones. In fact I think there were several types used on the class, and their appearance also varied according to which type of bonnet was fitted.

Having made the fittings for the vacuum ejector exhaust pipe from bits of rod, tube and M1 brass washers, I think I could have a go at making a couple of short safety valves the same way. 

 

[Galteemore]

That’s really nice work and neatly done. Wish my 7mm version looked as good !

[Mol_PMB]

9 hours ago, Galteemore said:

That’s really nice work and neatly done. Wish my 7mm version looked as good !

Thanks! I’m sure your larger one will look even better when it’s detailed up. 

[Mol_PMB]

I managed to find a couple of hours yesterday to use my friend's lathe to modify the axles for my J26, and to prepare a few more for other projects too.

Axles cut in half were set up in a collet and the end turned down in diameter using a homemade go/no-go gauge. There was a bit of slack in the lathe and I didn't have 100% success rate but my process improved through the batch. 

Back home this morning I prepared the brass tube sleeves and then assembled 6 axles. Four of these use the turned-down axle halves into a 1/8" OD tube to give an axle that's nominally 1/8" all along. The other two use the simpler approach of leaving the axle halves full diameter and fitting a 4mm OD tube over the halves. 

In both cases I was able to achieve a press fit and used my assembly jig to push the parts together. 

I drilled small holes in the tubes, and after the axles had been pressed together I fed some Loctite 290 into these holes. This is a very low-viscosity Loctite that seeps into the gaps by capillary action and takes 24 hours or more to set fully. So for now, I'm waiting! 

I have another busy week this week, including a flying visit to the IRRS archives in Dublin. So not much modelling time but hopefully some more research.

This week's eBay success has been the negative of this image, which will hopefully arrive in the next few days. It's good to have a clear photo of this side of the loco I'm modelling, most show the other side.

[Tullygrainey]

Excellent. Your little jig is a fine bit of work. Beautifully made and it seems to do the job well. A useful addition to your tool kit.

[Galteemore]

Excellent work all round. Photos are great - got to model that loose boiler cladding ! 

[Mol_PMB]

I continue to plough through the Irish Railfans' News, and have found a useful snippet on the Quartertown Mill branch.

Number 12.3, August 1966:

Special To Quarterstown
On May 21 the Munster Area of the IRRS organised a special train from Mallow to Quarterstown siding, better known perhaps, as Webb’s Mills. This was the first passenger  train ever to use the 90 chain long line which diverges from the Killarney Junction - Tralee line at MP ¼ and curves northwards to the short loop at the mills, now owned by Ranks Ltd and used as a store. The siding was opened in 1863 and on 8th February 1864 was the scene of an unusual accident when a goods train from Mallow to Tralee was diverted on to the siding and thinking itself on the main line made a spectacular pile-up at the mills. No such fate befell C212 when it propelled standard 1315 and LV 2756 south out of Mallow down platform on May 21 at 16:20. It was necessary to stop on the Kerry line and again on the siding, beyond the gate, for the opening and restoring of the points and at a crawl the train continued to the terminus. At 17:00 it, now hauled, started back, making a photographic stop, a gate stop, the junction stops and a stop at Killarney Junction waiting clearance of the 16:15 Cork to Limerick Junction goods (A30, transformer truck, 12 wagons, a van, 6 wagons and another van). Traffic on the siding is nowadays almost non-existent - the last working was in the 1964/65 grain season but up to about 1962 there were often 35 wagons per week in the season.

We've seen some photos of the special compiled by Colm Creedon, but this IRN paragraph gives a little more detail of regular operations on the branch and it's good to know how long the grain traffic lasted.

It's also good to confirm the coach used on the special - the IRRS Munster area records list it as 1350 but that doesn't fit with the photos - whereas 1315 does. 1315 was a 57' 8-compartment corridor second (previously third) built in 1925 to GSWR design, and it survived until 1972 though latterly renumbered 4032. Perhaps a future project for me?

 

Edited April 26 by Mol_PMB
corrected journal issue

[Westcorkrailway]

I wrote that history, my mistake

[Colonel]

Clever stuff, Paul and interesting to read about Loctite 290 too. Seems there's a cyano for everything.

 Since having to find 4mm scale drivers for my 7mm narrow gauge locos, it made me realise how valuable Slater's wheels are and wonder why the likes of Gibson and Ultrascale can't follow the Romford practice of square ended axles?

 It's not just the ready made quartering they offer either. It may be me, but I find building, fettling and painting a loco chassis requires multiple fitting and refitting of wheels, which Gibson's in particular do not like - a couple of removals and they are soon loose on their axles.

 Very neat solution to ensuring the axles will quarter correctly too, by the way.

[Mol_PMB]

Many thanks, David. I've also a long background in 7mm scale but now working in 4mm for the Irish models, and I completely agree with your comments on the wheel/axle interface. It also helps that the Slaters 7mm scale wheels have a metal insert, whereas the readily available square-holed 4mm scale wheels are all plastic (there were some with metal hubs or even entirely metal, but not readily available these days).

I've also found the wheels need to go in and out multiple times during construction, fettling and painting. I've read of some people who buy twice as many wheels as they need - one set for the building process and another set to fit in the final assembly.

It's one reason why I have come to prefer hornblock suspension because the entire wheelset including hornblocks can be removed in one piece. It's not a perfect solution though, it can very fiddly re-fitting them and that's without considering what to do about brake pull rods.

 

[Mike 84C]

Hi Paul, like the J26 very inspiring! lovely work on the body how/what did you use for the chimney?  Nearest I have found to a GSW/CIE style is a British GNR built up type.

Pretty busy in Wales last w/e.

 

 

[Mol_PMB]

1 minute ago, Mike 84C said:

Hi Paul, like the J26 very inspiring! lovely work on the body how/what did you use for the chimney?  Nearest I have found to a GSW/CIE style is a British GNR built up type.

Pretty busy in Wales last w/e.

 

 

Thanks Mick! Hopefully it will turn out well. The chimney is a GWR 14xx type, a nice lost wax brass casting. 

MT328: GWR 1400 Chimney – Wizard Models Limited

Ideally it would be a mm or so taller, but the styling is a good match. 

Glad to hear you're still getting to Wales.

[murrayec]

10 hours ago, Mol_PMB said:

.........

I've also found the wheels need to go in and out multiple times during construction, fettling and painting. I've read of some people who buy twice as many wheels as they need - one set for the building process and another set to fit in the final assembly.

......

 

I use a set of slightly undersized axles in the wheel area while constructing a chassis and then install the proper axles on the final build.

Eoin

[Bob49]

Always fancied a J26 does anyone do a kit in 4mm for one?

[Mol_PMB]

2 minutes ago, Bob49 said:

Always fancied a J26 does anyone do a kit in 4mm for one?

https://www.studio-scale-models.com/Locos.shtml

The SSM kit is what I'm using as the basis of my build. It's quite an old kit, well designed but I rarely follow the instructions!

[Bob49]

From your efforts I take they can be regauged to 21mm with out much fuss?

[Mol_PMB]

4 minutes ago, Bob49 said:

From your efforts I take they can be regauged to 21mm with out much fuss?

The kit includes frame spacers for both gauges, and it seems to fit. I'm still mid-build so bear with me for final confirmation!

[Bob49]

Sounds promising. I would need to expand the wagon range as well to make it work.

 

[Mol_PMB]

1 minute ago, Bob49 said:

Sounds promising. I would need to expand the wagon range as well to make it work.

 

I have found and photographed some previously-undiscovered wagon drawings in the IRRS archives...

[Bob49]

Sounds interesting.

Marc