Hello, I'm new here but as Nick has twigged that he is proof building my castings in his NGG16 build I first came to have a look at the build and the comments and then decided to chip in.
Now I used to drive the NGG16's but these days I stick to the Festy engines and only do Porthmadog to Blaenau but it does mean I see them on a regular basis as, in normal working, one is stabled at Boston Lodge. Occasionally we get two at BL and once this summer all three of them which caused something of a stabling crisis (can't recall why all three were at one end of the railway).
The model Nick is building was produced from artwork that was intended for 009, was hand drawn and to 8mm scale. For 009 the 50% photo reduction was just about enough and to get it to work in 009 some compromises were made that were acceptable like trimming the inner ends of the frames to clear the inner trucks. When it was then released in 7mm of the same artwork the photo reduction was wholly inadequate, highlights some of the drawing errors, leaves a lot of parts looking thin and underweight and, as Nick is finding, its not any NGG16 but bits of all of them with features such as the welded tank shape of tha later batches but covered in rivets like the early ones. The one batch it can't really be is the first batch built by Cockerill as they are really different and are nearer to being NGG13 but with a different inner truck. WHR's 87 is one of these.
Backwoods Miniatures offered the NGG16 in ready to run form assembled by SanCheng Brass. These differ from the kit as San Cheng replaced some of the kit parts to ease assembly. It was one of these that came to me and I then sold on. I started this rework for the new owner but when we realised how extensive and time consuming it was going to be and what it was going to cost a lesser option was his choice.
What inspired my work was this
Now this may not bother many but spending a lot of my time around real loco valve gears, and the NGG16's in particular, this worse than 1970's triang rendition offended me big time. The angular Union Link really hurt my eyes.
Just as a reminder this is what it should look like - this is #130 part approaching the end of an overhaul
Anyway, spurred on by how offended my eyes were I set to work in SolidWorks 3D CAD and modelled the valve gear.
On the model the support arms for the expansion links just looked wrong. This was the result of my efforts
The valve spindle guides really didn't cut it either made out of flat etch so this was my version complete with lube lines added
The castings were reamed 2mm bore and valve spindles made out of 2mm brass tube with a 7mm scale short handrail knob soldered in
And that's as far as I got.
The castings you have seen in Nick's post above were my CAD creating STL files and uploaded to Shapeways. Ordered in plain brass or plain nickel silver they printed waxes and had them cast. As a result these are first generation castings and haven't lost a little resoliution by being cast from waxes made in a silicon mould of the original part. They were arranged on the chunky sprues to defeat the Shapeways rejection of sprued objects. Despite ordering them plain they came coated in a lacquer and have been grit blasted to remove this so they would solder.
I suspect Nick will have to do some fitting work to get the valve rod fork end around the combination lever top and the hand rail knob end of the valve rod into the cut out as I recall problems with minimum thicknesses in the Shapeways auto check process.
If anyone wanted castings I could get more done but if Nick feeds back his experieces of using them I would be to do a mk2 version of the CAD.
I still have a couple of the Backwoods Kits here and one day I'll build them for myself but each time i look at them i think it might be easier to make my own kit