New Zealand A Class 4-6-2

[suctionhose]

Taking break from machining to figure out the rear frame extension, the back truck, draw gear etc

Had a cab mock up today:

[suctionhose]

People may be interested in my processes for trying to emulate a prototype from quite limited drawings and photographs. Ten years ago, I was not a user of CAD, however through a similar process over the duration of 7 years building the 1880 Ploughing Engine, extracting information from pictures, considering "how it could work" and inserting pictures to scale into CAD to get the general feel of proportions, provided the genesis of the detailed design. Of course the end result is a design that stands on its own merits, specific to purpose on 5"g track, though I aim to have the overall affect recognisable and capable of a degree of scrutiny.

[suctionhose]

Worked on the Cab and frame extension which is carried by the trailing truck The truck is a Coles type with wide axle boxes (not made yet) with slides that bear up against a leaf spring that is housed in a box beam located in the dark under the footplate.

The frame extension is almost ready to weld onto the main frame. It has been quite convenient to have it on the bench for the work pictured here.

[steamer5]

Hi Ross,
Looking good!
Nice details around the window & hand rails.

Cheers Kerrin

[suctionhose]

Plenty more detail possible Kerrin. Gotta keep an eye on the clock... More to go but not doing glazed windows with 16ba screws like some people...

[suctionhose]

Been away on holiday with family / catching up on chores / starting a new job and various "that's life" diversions.

Minor progress this week in order to re-cunje enthusiasm with events like joining the main frames to the rear frame extension / cradle / whatever. Also a hinged flap of yet-to-be-determined value. An occasion to exhibit at the club this weekend so hopefully priority for this build will bubble from deep in the swamp of daily life to nearer the surface and see some sunshine again...?!!

[stevendavis]

Wonderful work so far!!

[David]

I wish my bench was as tidy as yours! That is all looking great, as expected. Front end is excellent and splashers are interesting. So is the bogie centring idea and the cab looks good :)

[suctionhose]

Is it just me or is the Christmas ‘busy period’ earlier, longer and busier than ever???

Just to signal I’m alive and still working on the NZR engine, here’s the partially made fabrication for the back truck. Really slow progress on this one – can’t seem to get a run at it.




I’ve wrestled with two things: A simplified design that works on tighter-than-scale radii, with sufficient side to side and vertical travel and secondly, how to make it. A silver soldered fabrication of many pieces is the answer to the latter in which I’m hoping to machine a seat for a ball bearing each side. The face plate on the outer ends that appears prominently under the cab, will be L shaped, incorporating the bottom sump of the axlebox like the original.

The other recent progress, albeit outsourced, was having the builders’ and NZR number plates engraved. Chosen numbers, A410, being the first of many built by A & G Price with (hopefully) the correct serial number from the works to attached to the smokebox. Mucking about with 14BA csk screws today to mount the red ones on the cab sides!

[suctionhose]

Further to previous post, an indispensable tool for tapping 14BA in steel is this sleeve guide for the tap. The vast majority of tap breakages are caused by sideways bending of the tap so the sleeve guide eliminates that risk and gives confidence to just feel the tap through; backing and advancing as your fingers tell you is ok...






I bought two packs of 10 x 14BA csk screws which arrived by mail. I opened the first packet and oops: then there were nine! Tiny little bast**ds!
The second pack was incorrectly labelled - they were 16BA - so off to the model shop to fix their labelling issue... Anyway all's well that ends well and I can claim a personal best....: Previously my limit was 10BA with a brief sojorn into 12BA (2 screws) but a DIY watch construction (a mere distraction compared to designing and building a loco) provided a pair of excellent Swiss tweezers and a delightful set of screwdrivers...