Scratch build - LNWR Precursor Tank - Scale7

[adrian]

Good to see you getting chance to do some modelling Adrian.

Well that aged well. Pressures of work and other issues just left me drained in the evening so I never had the energy to pick this up. However just before Christmas I decided I had to get moving on it again. A few recent posts have shown a little more interest in pre-grouping and Precursors so I thought I would post my updates over the next few weeks.

The front, middle and rear parts of the side frames were clamped together with tool maker clamps and using a ruler across the top to make sure they were straight from front to rear before soldering them together. It was only at this point did I start to appreciate how damn long this tank loco is going to be!

I then set about making some more of the intermediate frames spacers. Also behind the buffer beams a mounting plate to enable the bodywork to be attached to the chassis.





Also additional brackets for behind the buffer beam - cut from a strip of nickel-silver, riveted along the edga and then folded.


Once all the parts were ready I started soldering together the chassis - no photos I'm afraid of that stage however no complex jigs used. It was assembled on a flat glass plate and as the hornguides were fitted rather than "alignment axles" I just used two length of brass square bar and careful checking with an engineers square.

 

[adrian]

So I now have a rolling chassis - with CSB suspension.

I have decided to make the buffer beam part of the chassis rather than the bodywork. I just think it'll make it easier to keep the bodywork straight and flat, the loco lends it to this arrangement for me just because it has a very thin straight side valence. Other designs with deeper side valences I might have done differently but for this loco it seemed an appropriate arrangement.

 

[SimonT]

Adrian,
glad to see you back modelling. I too had a 2023 full of other matters and have just started again. Good, isn't it!

The axleboxes look interesting. Presumably a 3D print in an ABS like resin. Do they have a brass bush inside like the original S7 insulated axleboxes? Were the horncheeks set with a jig or were they a muck about with the iron until they felt right?
Simon

 

[adrian]

The axleboxes look interesting. Presumably a 3D print in an ABS like resin. Do they have a brass bush inside like the original S7 insulated axleboxes? Were the horncheeks set with a jig or were they a muck about with the iron until they felt right?

Sort of - but nothing fancy.

The "axleboxes" are more like CSB cradles for miniature ball races.

Then for the hornguides I just soldered one side vertical checking with a square - this is illustrative only. I then used one of the Slaters insulated axlebox as a spacer to solder the other side on.


I then have a little steel peg to fit in the axlebox so I can use the coupling rods to space out to match the dimensions and solder in the hornguides for the other axlebox.




The slot in the frames are actually slightly wider than the hornblocks to allow the flange on the bearings to be slightly recessed which lets me get the frames a nice width and close to the wheels.