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

[Mol_PMB]

Starting anew in Irish 4mm scale modelling, I'm considering the gauge question. I thought I'd do some experiments to see how easy or hard it was to regauge rolling stock to 21mm, before making a final decision.

Of course it's more complicated than just the gauge. There are different wheel standards and back-to-backs to consider, which seems a bit of a minefield! For now I'm going to see what's possible by re-using the existing wheelsets.

 

Anyway, I started at the relatively cheap end of the scale and bought some spare IRM Y33 bogies as a starting point. It was fairly easy to remove the wheelsets and I was able to tap the axles through the wheels to achieve a 19.2mm back-to-back (which is one of the dimensions I've seen quoted). Assembling the wheelsets back into the bogies was straightforward and the wheels then had a much better alignment to the axleboxes and the representation of brake gear. This photo shows before and after on my dual gauge track:

I don't really have a use for these bogies at present, but they will be good for testing track as the wheel/rail interface is quite visible. I might re-gauge the other one and connect them with a strip of perspex for that purpose.

 

I'll describe the second project in the next post.

Edited 23 hours ago by Mol_PMB
correcting typo

[Mol_PMB]

Project number 2 was an IRM corrugated open wagon.

Again, it was reasonably straightforward to extract the wheelsets and tap the wheels along the axles. However, the maximum back-to-back I could achieve was 19.0mm - any more than this and the wheels rubbed on the back of the W iron mouldings. To achieve a largere BTB would require a thinner, more finescale wheel profile.

On this model, the brake shoes are positioned to align with the 16.5mm gauge wheels, foul the wheel flanges when the wheels are set to 21mm gauge. However, the brake gear is very simple (as per the prototype) and I found that by levering with a tiny screwdriver I could release the brake hanger from its mounting hole in the chassis.

I then used a small drill bit to slightly enlarge the tapered slot next to the hole, so I could push the brake hanger back in there. With a small tweak to the brake push rod safety loop, the brake shoe aligned with the wheel quite well:

It's not perfect but it looks fine from normal viewing angles. In due course I'll apply a tiny blob of glue to hold it in the new position:

I suspect that modifying the brakes on the forthcoming vac-fitted H van will be much more challenging!

 

Next I realised that the buffer spacing looked very wrong on the broad gauge track. On this model, the buffers are set to match GB rolling stock for some reason, and they ought to be further apart for an Irish vehicle. I decided to take the plunge and try to change them. Also, I wanted to represent a wagon retro-fitted with the larger buffers, like this one:

I was unable to remove the old buffers without damaging them badly. I temporarily removed the wagon body and sanded down the remains, and then re-drilled new larger holes in a better position:

The buffers I had in stock looked about right until I held them up against the wagon headstock, and then they looked too big! But looking back at the prototype photo the base of the buffers is a fair bit taller than the headstock section. I'll have a think about it and see if I can find an alternative buffer if I decide these ones aren't right. Any suggestions welcome!

In the meantime, here's a view of the bufferless wagon on the broad gauge track:

I've ordered a couple of wagon kits which I plan to build to 21mm gauge - that may be easier than modifying RTR where suitable kits are available.

 

My main stumbling block for the kits is the broad gauge wheelsets. I think I'll try the dodge of cutting the axle in half and sleeving it.

 

Please tell me if there are better approaches to re-gauging, or if you have advice on back-to-back, finer wheel profiles or sourcing wheelsets - I feel I'm stumbling a bit on the path to 21mm...

 

[Galteemore]

All of us broad gaugers stumble a bit! Looking good so far. Sleeving axles is probably a fairly cost effective way to go about it. And brakes are a pain. Some 7mm Irish kits are designed on the - quite reasonable - assumption that most people will build to 32mm, and the fold up brake gear designed accordingly ! 

Edited 23 hours ago by Galteemore

[Mol_PMB]

I have done the deed with the buffers, and I think it looks satisfactory.

It's very hard to get buffers perfectly straight, but I take comfort from the fact that the factory-fitted ones aren't 100% perfect either!

I have enough of these buffers to convert another wagon, so I might do that tomorrow or Friday.

The buffers I've used are X6495 Hornby Sprung Tender Buffers for Class B1. They're not a perfect match to the CIE self-contained buffers but they're about right.

Photo of the real thing from Neil Smith, showing the larger type buffers and how near they are to the outer edge of the headstock:

 

[David Holman]

 Am sure someone can give a definitive measurement, but seem to remember 6 feet or even 6'3 is the buffer spacing.

 As for axles, I use 4mm scale wheels on my 7mm scale, 21mm narrow gauge models, where the standard axle is 2mm diameter. Hence it is a simple matter to fit new axles from 2mm brass wire. The pin point ends are easily made by twirling the axle against a slitting disc in a mini drill, while using brass means the axles aren't attracted to the permanent or electro magnets I use for uncoupling. Have found P4 axles aren't long enough.

 Speaking of P4, have found that 4mm finescale/EM standards work perfectly well for 21mm gauge, without going the extra step. 

 Another option, rarely mentioned, is "Irish EM". I only came across it when looking on Templot for a set of points drawings, but it uses a 20.2mm track gauge - a similar proportion for 18.2 v 18.83mm standard gauge. On one level, one could argue why bother, but thinking about it, it might just mean the back to back will be just that bit smaller to avoid wholesale rebuilding of rtr chassis. I use 19.2mm back to backs and have found that if it is out by as little as 0.2mm, it causes problems on point crossings or Vs. This is with the standard one millimetre flangeways used in finescale 00 and EM.

 The wagons look great in the right gauge, by the way, but (if it isn't already in your plans), a couple of points will be essential on your text track to check whatever clearances and standards you use. Love the overall approach too as it could well point the way to more folk trying broad gauge.

[Mol_PMB]

Many thanks, that’s really helpful and plenty for me to think about. I will need to have some pointwork, but not sure what approach to use at present. 

Buffer spacing is 6’3” for the CIE wagons, whereas GB standard gauge is 5’7.5”, a 7.5” difference, similar to the track gauge increase. 

[Brendan8056]

Welcome back to the world of Irish modelling.

I have posted various bits here about re-gauging to 21mm. Rather than repeat myself you can hopefully search for my posts. Also I would suggest subscribing to "New Irish Lines", if you have not already done this.  The latest releases from IRM and Murphy Models are 21mm friendly. As David Holman does, I also make my own axles using a drill and some files, very little skill is needed, if I can do it.