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

4

40057

Western Thunderer
Brian McKenzie said:
Cast iron as a material may not take too kindly to broaching, especially if the wheels are to be broached full depth of the axle hole. I'd be wary of splitting a casting or wheel boss. I assume Tom is replicating some vintage practice.

Expanding on Adrian's suggestion of using a taper reamer - the taper at the end of a regular hand reamer would suffice.

(Hand reamers are easily identified by having a square at the end of the shank. Machine reamers have parallel flutes full length and no square on the shank.)
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It was ‘vintage practice’. Bond’s, Leeds Model Company and others all used a system where the wheel had a square central hole for quartering but the square hole was only about half the depth of the wheel. The end of the axle had a screw thread and the outer face of the wheel boss had a recess for a slotted nut that was used to secure the wheel. It meant the wheels could easily be removed and replaced (e.g. for replacing the mainspring in the motor) and the quartering preserved.
 
Tom Mallard

Tom Mallard

Western Thunderer
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Hello again,

here's a short update and snapshot of the L&B Manning Wardle project. So many little things needed either making or attaching (I'd avoided all the oilpots and lubricators - 4 types on the cylinder assembly! - plus completion of the cab fittings' installation til now). There was also the small matter of making the things run smoothly with all the properly working Joy valvegear...

Proper photographs will be done soon, but I was excited to show where these two had got to after a long gap in updates. The weathering is much needed now to highlight the small details and bring them properly to life.

The madness of the lone model maker exemplified in narrow gauge form.

Best regards

Tom
 
C

COEUR-DE-LION

New Member
What some exquisite workmanship Tom, the small details and complicated Joy valve gear are really superb, model engineering at its finest congratulations
 
Tom Mallard

Tom Mallard

Western Thunderer
Various other things have been on the workbench this year, including these chassis for GWR Saints. There's a fair few small differences between these chassis, including cutouts for one which meant a representation of the inside motion felt necessary. The bogie frame is a little different, and the brake hangers will be too. Cylinders are also slightly above the axle centreline on the model with frame cutouts which will show a little more once the bodywork is in position.

Wheels are the fantastic Ultrascale product (GWR modellers have always been fortunate) gears for the custom gearboxes are by High Level.

The clockwork model of Caledonian Railway 828 is quite near completion after a fun time reproducing square holes in the wheels for the original pattern axle. It travels quite quickly under test but is governed by an ingenious adaptation made to the mechanism which smooths out the power delivery extremely effectively.

Enjoy your modelling

Tom

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Dave Holt

Dave Holt

Western Thunderer
Very neat indeed, Tom.
Boy, the front and centre drivers are close (P4 rims?) - not much room for brake hangers. How does that work? (BR 9Fs had a similar issue, but on them the hangers were behind the wheels, near the frames, then stepping out in line with the wheel treads below the blocks).
Dave.
 
Tom Mallard

Tom Mallard

Western Thunderer
Hawkeye said:
Beautiful work as always! How did you make the square holes, by the way?
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Thanks very much! The holes were bored slightly undersize, then machined very closely to width over faces using an indexing attachment and a 1.5mm milling cutter, followed by hand finishing to fit the axles. This might have various flaws from a workshop practise point of view, but it worked far better than the aborted square push broach method I started out with (this wandered off centre based on lack of experience, poor technique and lack of appropriate equipment such as an arbor press). the wheels were all plugged, and I started again...
 
Tom Mallard

Tom Mallard

Western Thunderer
Dave Holt said:
Very neat indeed, Tom.
Boy, the front and centre drivers are close (P4 rims?) - not much room for brake hangers. How does that work? (BR 9Fs had a similar issue, but on them the hangers were behind the wheels, near the frames, then stepping out in line with the wheel treads below the blocks).
Dave.
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They sure are Dave! The front brake hangers are very compact and locate more or less on the bottom edge of the frames. The earlier batches maintained this approach for the remaining pairs, though later batches switched to more normal longer hangers for rear pairs.
 
Phil O

Phil O

Western Thunderer
Dave Holt said:
Very neat indeed, Tom.
Boy, the front and centre drivers are close (P4 rims?) - not much room for brake hangers. How does that work? (BR 9Fs had a similar issue, but on them the hangers were behind the wheels, near the frames, then stepping out in line with the wheel treads below the blocks).
Dave.
Click to expand...

Dave,

When I talked to Colin at Alan Gibson, about wheels for a Star, he suggested going down to 6ft 6ins wheels. On the prototype they would be worn, but still above scrapping, to gain some clearance.
 
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