A Broad Gauge Adventure - Nick Dunhill's Workbench

[nickd]

I have to confess to being a bit out of my comfort zone with this project, so I was a bit unsure about whether to upload this.  I have been commissioned to build a pair of Armstrong Goods convertible locos from Scorpio (loco) and Broad Gauge Society (tender) kits.  There seems to be a paucity of information about the broad gauge versions (photography in it's infancy?), but fairly lenghty chats with Pat Ennis at Scorpio and Peter Boyce at the BGS put my mind at rest.  

 

The tender kits from the Broad Gauge society are ok.  They are a 4mm blow up but the difficulty I encountered wasn't becouse the kit was lacking, but more because of the shape and method of construction of the originals.  I guess the originals were beaten from wrought iron by blacksmiths (Bessimer converters didn't appear until the 1870s, so no cheap steel in large quantities) and the designs are very reminiscient of a (horse and) cart.  The tank sides are made of sections of wrought iron sheets, joggled at the ends and riveted together (no TIG!)

 

The first problem I encountered was the lack of an inner chassis.  This is of course a 7mm peculiarity, we use wheels without outside bearings to simplify tender builds.  I decided it would/might be fun to build a Finney style rocking beam inner chassis.  I saw that BGS track standards are more like S7 than FS so compensation may be key.  I think the tenders turned out OK, there's a lot of etches to fabricate parts that may have been better as castings (yikes if you're making the 4mm version!) but it goes together ok with a bit of care.

 

 

 

 

There's more photos on my Flickr page here https://www.flickr.com/photos/144381574@N05/with/51154713811/

 

The next part of the job was building a test track, as Peco haven't ventured into the niche area of BG.  I mithered Paul Scott (very modest man who is at least as good as Norman Soloman) and Richard Spoors for help and took my first plunge into trackbuilding of any kind.  Tony Geary was kind enough to send me some simple Templots (and a bucketful of encouragement) which I stuck to a laminate board.   I built half track, outside rail first (thanks Richard,) then laid the inside rail using a BGS track gauge.  It ain't going to win any prizes for the best looking track ever but it seems to be ok.  The rail is BGS bridge rail.

 

 

 

Then onto the locos.  I built a Scorpio Queen last year and was very pleased with the kit.  I assumed that this one would be of a similar quality, and so far it is.  It has a million etches (or so) for all the various versions.  The outer splashers for the BG version are feindishly difficult to form.  The valances have to match the radius of the tyres of the wheels.  It took ages!  The kit is designed with a rocking beam compensation system which I didn't like the look of for coupled wheels.  I decided to convert the dummy outside bearings to be the working ones, and leave the inner chassis as a dummy.  This left me free to make a proper ashpan to hide the motor and fill with balast.  It was quite tricky to modify cast dummy horn blocks to work effectively, but I lucked-out and the 3/16'' ID K&S tube I earmarked as bushes for the axles had an OD that was the same diameter as the horn cheek spacings in the outer chassis.  I let short lengths of the tube into the dummy horn blocks and all worked fine.  I made crude suspension from phosphour bronze wire and added pick-ups.  

 

 

 

 

 

 

 

 

 

 

 

Currently I'm fettling Laurie Griffin inside motion parts.  I'm copying the dimensions off the dummy cast set provided in the kit, what could possibly go wrong with that?

Edited May 3, 2021 by nickd

[Scorpio7uk]

I don't know why 7mm manufacturers use inside bearing wheels for outside bearing tenders either!

 

With this in mind, the GWR 2000 gallon tender I've almost finished designing will be outside bearing only.

 

I believe that inside bearings on the Armstrong Goods were on the crank axle only and didn't touch the outer axles - we only put bearings on it for convenience at the time.

 

I hope the valve gear works out - I was about to say that you've got more room being BG, but of course you haven't!

 

Thanks

Jeff

Scorpio Models

[nickd]

Hi Jeff

Are the cast whitemetal horn guides for the outer or inner chassis?  I understand that the rear axle is only supported on the outside frames.  The front axle is supported on the inner and outer frames but only sprung on the outer frames (hence your correct beefier spring castings for outer axles.)  The centre axle is supported and sprung on the inner and outer frames.  Do you think this sounds correct? 

 

Your cast dummy con rods are the right length so thats encouraging.  With this type of arrangement the lengths of the eccentric rods isn't that critical as they pass through the motion bracket and won't smack up against it.  The valve stem will take up the difference.

 

I could do with someone to make me a set of slimmer eccentric sheaves if there's anyone out there who fancies a quick machining job.  Full expenses paid.......

 

Nick

 

[Scorpio7uk]

You are certainly right about the frames and springing, but I'm not certain of the Whitemetal horn guides 

 

Dad designed this kit about 20 years ago so bear with me..... and the instructions don't make this any clearer as the casting doesn't seem to be used!

 

The outside frame horn guides are represented by etchings, so the castings would seem surplus for that purpose, but the rivet pattern does match up with the frames and there are six of them!

 

Personally, I would use a pair of them for the inner frames, on the crank axle (if you can fit them in) as this is more visible.

 

Sorry I couldn't be more definitive....

 

Jeff

 

 

 

 

 

[nickd]

A quick catch up.  I have done a fair bit to the valve gear this week.  As mentioned above I have ordered a large batch of eccentric sheaves to replace the LGM castings.  The cast ones have an OD of 9.8 mm and the eccentric strap ID is 9.0 mm.  Therefore the eccentrics and/or straps need a lot of fettling to get a good fit, and it has to be done by hand so customer has to reconcile a big labour cost.  The LGM ones have a flange cast on which makes them too thick so if you use the cast LGM valve guide the outer eccentric rods have to be dog-legged slightly to bring them into alignment with the sheaves.  I ordered 100 which is enough for 25 two cylinder locos (in the last 12 months I've made 6 sets!)  I'll have a few sets to spare if anyone wants some.

 

 

So the week has been spent fettling rods and building cylinder bottoms and drain cocks and a few other odds and ends.

 

 

 

The way the inside motion is arranged in the loco results in eccentric rods that are near the maximum length for the castings.  I took the approximate length from the dummy set in the Scorpio kit and, with a bit of advice from my dad (engineer, retired) they seem to be about right.  I'll know when the eccentric sheaves arrive, but you can work it out from the throw.......I hope.

 

 

 

 

Brakes next week, well on at least one loco.  The pic of 1207 I have shows it running with no brakes on the loco .

 

 

[nickd]

It was fettling and fitting-up week in the Dunhill workshop.  First the brakes, I had a choice of etched or cast brakes for one of the locos.  One kit had both options but oddly the other kit had had the etchings removed from the fret.  It was a bit of a moot point anyway as the other loco didn't have brakes, eek!

 

Both locos had springs and buffers so a day was spent listening to R4 and fettling many many springs, dampers and hangers.   They required a lot of concentration to assemble and locate on the footplate.  I found it was better to solder them up in-situ.

 

The buffers were decent castings but blind, drilling them out also required a modicum of concentration!

 

The pics below show the model with the dummy inside motion fitted.

 

 

 

 

 

 

 

Also this week a packet of machined eccentric sheaves arrived.  They are a direct replacement for the cast ones in Laurie's inside motion kit.  They are excellent and hopefully will make the assembly of the crank axle much less troublesome (see next week.)  Thanks to Simon Dobson for making them for me.

 

 

[nickd]

The week began by soldering up my crank axle.  Care was needed spacing out the sheaves and the cranks and pre drilling the sheaves for a locating pin to hold them in place prior to soldering, but here's the result.  I had to crank the chassis by hand as I don't have any motors/gearboxes yet.

 

 

 

See how aggressive a flux that Baker's fluid is!  Cleans up OK though...

 

 

 

This was a first, the motion went together first time and did so without any binding or jerkiness.  Thanks again to Simon D for making the replacement sheaves (I have a few left if anyone wants some.)

 

The tender springs turned up and I was able to finish both tenders.  Here they are for comparison.

 

 

 

I looked at the pre-rolled wrappers for the boiler, smokebox and fireboxes.  They were etched in 0.0015'' brass and I decided that it would give a better result if I substituted for 0.0010'' nickel silver, as it would be easier to bend, either by hand or slip rollers.  Here's the way fabrication has progressed.

 

 

 

 

 

 

 

[nickd]

So the next step was to solder the three components of the boiler together.  I used the Scorpio boiler and firebox formers and they had alignment holes for some 0.8 mm brass rods.  I had to enlarge one of the holes to 1.0 mm to get a bit of wiggle room but they pretty much aligned the boiler and firebox perfectly, then I started to add the boiler bands.  I asked around but no one does a cast GWR firebox band tightening cleat (surprising as lots of GWR locos have them) so I had to make some from tube and wire.  I fitted the safety valve and cover and made the last firebox band stop just where the brass cover touches the firebox top.  

 

 

 

I had to put the boiler and smokebox on the loco check all was level and get the correct alignment.  I made a brass ring from 1 x 1 mm brass square rod to represent the brass cover that appears on lots of GWR boilers to cover the fixing bolts.  When I was satisfied all was well I tack soldered the join and finished the joins and bands etc.  I have to say that the Scorpio formers are pretty accurate and all ent together without much tweaking.  The etches in both Scorpio kits I have made have been of a good quality and fit.

 

The dome casting was a bit grotty but it came up well.  if you look very carefully you can see where I have filled the worst holes with solder!

 

 

 

I did some other embelishments, such as the plate join and screws along the boiler top.  There are also boiler band cleats along the bottom of the boiler but you can't see them in the photos.

 

 

The chimneys are cast in bronze but were wildly different colours, so much so that I thought one was a brass casting.  I rang Pat Ennis and he assured me that the lighter colour one would darken if I wafted it over a gas ring.  He was right!  I suppose bronze is another one of those alloys, like brass, where there's not an exact stoiciometric mix.  Must remember that for the future.

 

So here's a couple of shots of them mocked up for the camera.  Just the cab interiors and boiler pipework and handrails to do.

 

 

 

There's more photos of the build here; https://www.flickr.com/photos/144381574@N05/with/51210301378/

[nickd]

A shorter week's work due to the much welcomed sunny Sheffield Bank Hol.  It doesn't really look like I achieved much this week but it's all been about the behind the scenes stuff.  I've attached the cab and boiler/firebox/smokebox assemblies to the footplate.  I think this model is unique in that it is the first model I have made (although thinking back this might also include an original Piercy B1 I built ages ago) where the loco is almost in one lump.  The inner chassis is detachable but the outer chassis, footplate and body are one assembly.  A problem for the painter to resolve!  I did make the cab roofs and backheads detachable to hopefully help things along.

 

The instructions provided in the kit give fair warning that gaps will appear in front of the cab and footplate and front of the firebox.  These were dealt with fairly easily.  Some adjustments had to be made to the springs that are shoehorned between the cab sides and splashers, and a number of other small issues and adjustments were made.  This is the state of play as I post.....

 

 

 

One of the models depicts a loco that had the injectors and clacks on the boiler side and the other with the injectors under the cab and clacks (presumably) on the backhead.  Basic physics might suggest that injecting cold water into the firebox water jacket might not be a good idea?  Anyway the visible injector/clack pipework is also detachable.

 

 

The loco with the visible injectors also has the whistles on turrets in front of the cab.  These have been scratchbuilt from tube and rod and will be attached to the firebox first job on monday morning.

 

 

I have also prepared the backhead castings with their cast brass surrounds and planked the cab floor.

 

 

One of the locos has tender mounted guide poles for the emergency communucation cord and I'm not sure where the bell for it would be.  On the Queen class I built last year it was on the cab side.  Is it in the same place on these locos, can any of you GWR buffs advise?  

 

The last pair of jobs will be the backhead details and boiler handrails early next week.  At that point the job will be delayed as I don't have any motors.  I am 'patiently' awaiting deliveries from ABC.

[Scorpio7uk]

The bell might be in the cab........

 

These pictures tend to show the guide poles on the tender but no sign of the bell....  https://broadgauge.co.uk/locomotives/a59_388_class_convertible.shtml 

 

The more conventional position would be on the right hand tender frames, as shown on the first couple of shots of Iron Dukes on this page http://www.gwr.org.uk/no-tenders.html  (it tended to be attached above the footplate on SG tenders)

 

Other then that - not sure - but I think it's safe to assume that if the poles are still being used and there's no sign of the bell outside (on the drivers side) then I think it must be in the cab somewhere.

 

Jeff

 

[Miss Prism]

The bell tends to be at the front of the right-hand side of the tender frame.

[nickd]

Thanks for getting in touch  Miss P and Jeff.  I think I'm going to run with the photo which shows the bell on the tender frame.  I'm making nos 1205 and 7 from the photos in the RCTS book.  They were both converted from SG locos and paired with recycled tenders.  I bet they just never removed the poles and gong on the tender of no 1205 although they were only used for freight.

[nickd]

Thanks to everyone who helped with the bell here it is on the tender sole bar.

 

 

Last week I completed all the cab and handrail details and both locos are complete.

 

 

 

 

All the backhead fittings are a bit wobbly as they're only loosely fitted up, removable for paint.

 

 

 

There's quite a few more pics here;  https://www.flickr.com/photos/144381574@N05/with/51240898567/

 

The locos are in a box waiting for delivery of ABC motors/gearboxes.  Is anyone else experiencing a delay with orders from ABC?

[nickd]

The ABC motors/gearboxes have turned up and have been fitted.  Here's a crap unedited and mercifully short video of the valve gear and the loco on a short test run.

 

 

It's off to see Warren Haywood for a date with his felt tipped pens tomorrow.

[Scorpio7uk]

Wow! - they had some really steep gradients on the Broad Gauge!  

 

Jeff

[nickd]

Reassembly time!

 

 

 

 

 

I will assemble the second loco next week and post more pics.  Both painted by Warren Haywood.

[Craigw]

Nick, 

 

I always enjoy watching your builds and am particularly impressed with your ability to just get on with it. This is absolutely superb (as I would expect) ... how can anyone not love broad gauge?

 

Craig W 

[nickd]

Just to close this thread here's a few pictures of the finished models with coal in the tenders.  Ready to go to work.  Thanks to everyone who helped with the build.

 

 

 

 

There's more here  https://www.flickr.com/photos/144381574@N05/with/51642177010/