Tom Mallard’s Workbench L&B in 7mm scale, CR 828 in 7mm, GWR Saints in 4mm

[simond]

I use this

Silver Solder Paste 10g Easy, Syringe

I think it was recommended by Giles Favell. I haven’t much experience with it yet, but it certainly does the business.

It is fundamental to get a complete melt in one go, as it doesn’t remelt.

I use a piece of marble wall tile as a heatproof work base. This can easily be drilled with TC drill bits which means it’s possible to use pins/wedges to hold the work.

HTH
Simon

 

[adrian]

Yes! Show me what to do, what to buy, etc

There's a challenge and a half.

So I've added a post to my previous thread so show how I would make the brackets
Very Little Gravitas Indeed*

I hope it is useful - plenty of other good advice in the thread but if there is anything I've missed or is not clear then please let me know. Don't get me wrong - silver-soldering isn't the universal panacea. It's just another useful technique in the scratchbuilders toolbox and there are instances where it can be useful, it's having the option available when you need it.

 

[Tom Mallard]

Some machining and fiddling to produce the main brake parts. The hangers and shoes were cut along with all the original profile milled parts at the start of project and I'd successfully put off finishing this machining job for some time since although they come in pairs, each hanger is unique. the spacing of the twin hanger mounts was set in a jig using a pair of vertical pins in a piece of paxolin. Basic stuff but quite important to position them correctly during soldering. More little bolt heads were made - they get everywhere - on the model and on the floor and lost in swarf round the lathe sometimes!

Best regards

Tom

 

[Tom Mallard]

Yes! Finally getting there, with the engine's brakegear mostly resolved or at least all the parts I consider to be the most demanding.

The inclined cylinder cladding was a fiddle to seat the top edge precisely against the valence - so lots of checking and fitting of these.

Short stubs locate the hangers in their stirrups, and the brakegear springs in nicely as compared to 4mm scale as everything is much stiffer. The pull rods are made from two sections of etched N/S with a selection of machined parts to reproduce the turnbuckle.

I know it will be quite long, but I ought to write a list of things left to do before pattern making commences...

Best regards

Tom

 

[Jon Nazareth]

View attachment 113071
Some machining and fiddling to produce the main brake parts. The hangers and shoes were cut along with all the original profile milled parts at the start of project and I'd successfully put off finishing this machining job for some time since although they come in pairs, each hanger is unique. the spacing of the twin hanger mounts was set in a jig using a pair of vertical pins in a piece of paxolin. Basic stuff but quite important to position them correctly during soldering. More little bolt heads were made - they get everywhere - on the model and on the floor and lost in swarf round the lathe sometimes!

Best regards

Tom

It never ceases to amaze me how clever some people are in producing such small and very fine pieces, well done.

Jon

 

[Tom Mallard]

More of a 4mm scale Great Northern theme this time as the Compound is having a rest from construction. It was quite a rude return to 4mm scale and it's idiosyncrasies as my fingers relearned how to control smaller and thinner pieces of metal. There is the start of an understanding why modellers usually only work up through the scales and not down.

The project in this instance is to be a LNER O1, for which both tender and engine are developed from my own etch designs.

The tender design stems from my earlier work on a trio of Gresley O2 engines, so that was less of an unknown. The engine itself was designed back in 2015 as a set of etches. It's only this week that I have begun removing parts from the frets to check the design, and identify any omissions. It's not too bad, but there are a lot of bits!

Before anyone gets any ideas, it is absolutely not available for sale as an etch - it's a means to an end for me and I think it would betray the client's faith in my 4mm scale approach if I were to sell them 'off the back of a lorry'. But I still thought some of you might like to see them out of curiosity...

Best regards

Tom

 

[P A D]

Hi Tom,
Incredible work on the compound and everything else on your thread.

Not that you need any help with reference photos, but I thought you might like this. I took it at Barrow Hill when I was there recently. Shame the steps are in the way.


Cheers,
Peter

 

[Tom Mallard]

That's a great photo Peter, and it looks to me as though it's been properly cleaned compared to when I visited back in 2015. I had a good wander around on top of the boiler, cab and tender and it was completely filthy - not sure if from it's own running or from other engines...

 

[Dikitriki]

They've even polished the Slater's axle screws

 

[Tom Mallard]

The O1 tender is done, but now needs an engine to pull it. Not much has been done in this area beyond the pony truck frames.

The chassis is sprung, and currently is sat a little high on its springs. They're adjustable and adding the coal and so on will mean properly setting the ride height will happen more or less as the last thing to do.

Best regards

Tom

 

[Tom Mallard]

Some busy images of the sub-assemblies forming for the O1 and the cab/boiler/smokebox are just sat in position for now... I had forgotten the kinds of daft things I put in as etched parts such as the fold up sand boxes and built up reversing lever. Quite surprised i hadn't tried to etch the wheels. It's always a bit of a game reasoning which parts are suited most to etching, and after my 7mm scale foray I think the list shrunk a bit. However, etching is fantastic for making things fold up accurately, locating things with tabs and slots, and putting holes or marks for embossed rivets exactly where they're wanted. Dimensionally it is also really accurate for things like centre to centre measurements.

I use High Level gears for most of my gearboxes, finding them much more forgiving than everything else, and with nice simple metric hole centres. Since Chris at High Level had his own tooling made, the quality of them has improved, too.

Tom

 

[Tom Mallard]

Much fitting, filing, fettling and so on before the top and bottom of the engine mated satisfactorily despite a lot of careful design. There's still more to be done as it turns out I hadn't investigated the clearance of the cross-head to the coupling rod... I think there are several small compromises in the dimensions over the wheel boss crankpin seat, crankpin top-hat part and limitations placed on using an etched laminate for the rod that have absorbed all of the clearance in this area.

Obviously there's not that much on the prototype, but even in Scalefour as this model is, there needs to be very close attention paid. Designing the etches in 2015 didn't help my recollection of what I had or hadn't allowed.

If I remember, I don't think I will use half etched 10 thou nickel silver for the footplate again: the half etched edge is well under 5 thou and very prone to damage so not practical in a model where lots of test fitting is required. The long flat areas are reinforced with doublers so I'm not worried about that. Very pleased with the characteristic crease in the cylinder cladding though.

Boiler fittings are very temporarily fitted...

The majority of the toughest build areas are done. The chassis I think must consume about 70% of the total build time with a lot of dimension critical tasks adding up. Two small patterns for the valve guide and valve tail guide have been sent to the caster, so should be in hand shortly.

Tom

 

[John Duffy]

Blown away by the standard of this work. Very impressive.

John

 

[Dave Holt]

Very nice, neat work, Tom (as always). I can sympathise with the cross-head/coupling rod clearance problems having experienced a few myself, despite measurements and calculations before construction. I think that often, the wheel bosses protrude too far from the outside of the rim, certainly with standard commercial wheels. The other problem is that a clearance of 1/4" on the full size is quite generous, in 4 mm scale it is almost an interference fit.
Dave.

 

[john lewsey]

Really lovely work

 

[Tom Mallard]

Cheers, all.

Dave, the wheels are Exactoscale and as such have a very fine appearance. Basically I’m trying to build a model which matches the standard of the wheels!

However, I have found that a specific feature of the moulded wheel part places the seating for the crank pin top hat well proud of the face of the tyre, and as in all other cases this was only noticed after the top hats had been loctited into position. Maybe on future models using these wheels I will take this off to mitigate clearance problems before they arise.

Those locomotive engineers seem not to have considered the plight of the small scale railway modeller when leaving their idea of adequate clearance - it isn’t something that scales very well as you say. I blame the paltry loading gauges we have on this island...

Sorry about veering toward having an opinion on anything...

Tom

 

[45609]

Hi Tom,

All looking good. Please show me a close up of the weigh-shaft bearing just behind the second driving wheel? I'm interested to know how you have approached the fabrication of it. I recently dug this out of the "must finish" pile.


It is the base for an LMS water crane. Intended for casting. The four triangular webs on the top flange were a challenge to fabricate accurately as well as getting the flange at the prototypical shallow angle that makes the crane head swing back to a position parallel to the adjacent track.

Cheers...Morgan

 

[Tom Mallard]

Hi Tom,

All looking good. Please show me a close up of the weigh-shaft bearing just behind the second driving wheel? I'm interested to know how you have approached the fabrication of it. I recently dug this out of the "must finish" pile.

View attachment 119991
It is the base for an LMS water crane. Intended for casting. The four triangular webs on the top flange were a challenge to fabricate accurately as well as getting the flange at the prototypical shallow angle that makes the crane head swing back to a position parallel to the adjacent track.

Cheers...Morgan

Morgan,

very shiney!

It's pretty straightforward with an etched base where it attaches to the frames with half etched grooves to orientate the ribs (none of which is at 90 degrees to it's neighbour)... The ribs themselves are tacked at one end then the other and I get the solder to run together with my RSU. Close up is a bit ugly though it isn't very big at 2.2mm across the end of the bearing, but you get the idea.

Tom

 

[Tom Mallard]

Among other things, much detailed work has taken place on the body. The lubricators on the RH footplate are modified from those fitted to my O2 and K3 models to sit flat on the footplate with all feeds exiting laterally instead of downwards. The pipe brackets between the RH handrail and boiler are built up from 1/2 round 0.7mm N/S wire, annealed and formed around the wire, and cross drilled 0.4mm to fit the tail of a truncated handrail knob. Overall it turned out that every handrail knob was refined, modified or otherwise adapted as required. They came originally from either 247 developments or Markits

I think the Great Northern did a very good job of designing attractive chimneys and domes. Strangely, the dome presented more problems than the chimney in my efforts to reproduce the elliptical curve of the top, and the smallish flare at the base but I think I got there in the end.

Best regards

Tom

 

[Tom Mallard]

I've filled in the gaps on the body, leaving just the backhead to finish. I mentioned previously that I thought 70% of the time taken to build the model was being taken up by the chassis, but might revise that downwards after taking more time than expected to complete the detailing on the O1.

Back to the chassis now

Best regards

Tom