This series of posts is intended to document the build of a Midland 3F loco and tender as supplied by JLTRT. It is another loco that was photographed around Tewkesbury so was is one to add my fleet of locos.
The kit was originally produced by Eric Underhill and was bought out by JLTRT. The kit is a mixture of etched nickel components, whitemetal castings and resin components for the boiler, firebox and tender body. Some instructions were included, whilst the words might have made sense the drawings were woefully inadequate. I’ve seen better images from a fax machine.
Dummy Side Frames
A start was made on the tender by digging out the main components to gauge how it would fit together. It soon became apparent why people refer to them as NQLTRT. Just putting the axle box castings on the side frames to work out how to set out the chassis quickly demonstrated that something wasn’t quite right with the supplied etches. The shape of the side frames contains numerous dimensional errors.
As can be seen in the photo the oval cutout, marked A, is in the wrong place being too far to the right to the extent that the cutout disappears under the axle box No.3! It should be central between the two axle-boxes. On top of that the curve at the rear, marked B, is wrong as well, again disappearing under axle box No.3. The frames also stick out from under the axle box which they shouldn’t and finally across the top are tabs to slot into the baseplate of the tender. Unfortunately these don’t line up with the slots in the tender baseplate!
JLTRT was contacted about these errors and they acknowledged the problem but they said it’s an old photo etch tool and it would be prohibitively expensive to update. Although they did say that they may get round to correcting the errors in the future. Which was disappointing to say the least. They seem to be quite content to include many duplicate white metal and lost wax brass castings in the kit but are unable to include a couple of new etchings for the side frames.
Anyway something different was required for the inner chassis. The kit is supplied with an inner chassis that makes up into a rigid chassis but I prefer something with springing and split axles. Therefore the intention was to get these etched as I have a few other Midland locos planned so they would prove useful later on.
So I looked to the various guidelines on drawing up artwork for etching, I downloaded Draftsight to try out but I struggled to get my head around it. It just didn’t seem to work as I expected it to do. So looking around for other alternatives I tried QCAD and liked it, even better it was free and works natively on Apple Mac computers.
So my first effort at etched artwork was to redraw the outer frames to the correct shape and tabs in the correct place to fit to the tender base plate. These were going to be easier than modifying those supplied in the kit. I had to fill the etch sheet so I have a few spare side frames if anyone else is interested in tackling the kit and would like a set of accurate side frames. Alternatively I’m quite happy to supply the drawing if anyone wants to do their own etching.
Replacement Inner Chassis
I also drew up a design for the inner chassis, the idea was to use split axle insulation combined with Slaters insulated horn guides and a continuous springy beam suspension system. This did need a little care with the frame spacers to include gaps for the spring wire. The design was sent off to PPD, the service was excellent and the following etches were returned.
The parts were separated and folded up. There are small tabs included to be folded up for the CSB fulcrum points, these have a short length of pcb soldered to them so that the spring wire will be electrically isolated from the chassis.
Something went slightly wrong with the slots on the frames, slightly too wide for the tabs, but fortunately all in the right place. This is the chassis assembled just on twisting the tabs, not soldered at this stage.
The wheel slots have been sized for Slaters insulated horn blocks, although I have included a small fold over tab at the bottom so that the keeper plate can be screwed in from the bottom rather than the side. Here they are just clipped in, no glue as yet. Just waiting for some small BA screws to screw and glue in place.
The tender chassis was finished to a running state. It works fine and is nicely sprung, however the PCB fulcrum points were a little fiddly so the next iteration I might look at using the etched horn guides from Steph and the Slaters insulated axle boxes otherwise it seems to work as I want it to.
Building the chassis
So I then I returned to sorting out the cosmetic chassis. My etched frame is at the top, that supplied in the kit is at the bottom. Note that the outer tabs at the top of the frame are in completely different locations on the two etches.
Guess which one fits in the tender footplate supplied in the kit?
Yes that’d be mine.
Now that’s the end of the good news. The rest is depressing – I often see people refer to JLTRT as NQLTRT, I’m sorely tempted to say FALTRT ( you can work it out yourself). It’s got to the point where I’m sorely tempted to chuck all the bits back in the box and stick it back on the shelf. I’m quite happy scratch building stuff but I thought I’d save a bit of time getting a decent kit that I could just throw together without thinking too much about what I’m doing.
It just seems that every component I pull out of the box is dimensionally inaccurate. After the palaver of the side frames next is the rear buffer beam.
Yes the rear buffer beam is actually nearly 3mm wider than the footplate. According to the drawings the buffer beam should be 7′ 5″ wide, that supplied in the kit is 7′ 11″, a full 6″ scale or 3.5mm model too wide. So now I’m left with the hassle of checking the dimensional accuracy of very single etching because I no longer trust them to have got it right.
I scratch built a new buffer beam from some nickel silver sheet and built up the tender cosmetic chassis.
To finish off the chassis I returned to the inner chassis. The next major issue for me was the cast brass brake shoes and hangers. Having gone to all the trouble of making split axles and taking care of insulation sticking bit lumps of brass as close as possible to the wheels didn’t strike me as a good idea. As far as I was concerned there were two options either insulate the brake hangers from the frame or replace the brakes with insulating versions. In the past I have always made brake shoes from paxolin sheet for this reason. However this time I decided to use it to practice with Onshape and laser cutting.
I was pleasantly surprised how quick and easy it was. A quick photo using my phone (found a magnifier mode in accessibility settings) was uploaded into OnShape. I then drew a circle and set it as the wheel diameter so that I had something to scale the image to the correct dimensions. I then sketched around the brake shoe.
This was copied a couple of times and tweaked for the different shapes on separate layers, effectively like several etched overlays I was building up the shape from several layers.
I could then easily generate a drawing from this 3D image – export it to a DXF file. Import it into the laser cutter software and cut out the various layers.
I made the frame around the outside to align the various layers. So no more than evenings work I had made a test sample for comparison with the brass casting supplied.
I was more than happy with the result so altered the drawing to make 3 brake shoes in one set.
These were then fixed to the hangers and soldered into a unit to clip into the tender frame so that they could be removed to enable the wheels to be removed.
Rolling Tender Chassis
So now there is a rolling chassis and dummy chassis. The next stage is to look at the upper body work on the tender which will be another post.