The tender horns and axle boxes are made from brass stock material, with bronze bearing bushes. I could have chosen to use roller bearings, but these would be very small due to the limited space.
The horn cheeks have a radius shape at the bottom, so a CNC milling machine was used to produce them. The axle boxes are a straightforward milling job, done on a conventional milling machine. See the next post for that.
These are the real horns and axle boxes of the preserved Y-14 at the Norfolk Railway. The 3D design was created using photos only.
Setting up the vice at 90 degrees was done so that the main movement of the end mill occurred along the Y-axis. This is the sturdiest movement of the machine, directly connected to the vertical column.
Using a 10 mm end mill with depth steps of 2 mm in the Z-axis, it took about 45 minutes to complete one horn cheek. If I had used a smaller end mill and milled the side supports as well, the production time would have been much longer. So, I opted to make these supports separately.
After the roughing milling process, the start of the finishing cut with a depth of 0.3 mm, using steps that are 2.5 mm deep. This gives a good surface finish.
One horn cheek CNC-finished
Six left horn cheeks. The right ones are a mirrored version of these.
The slots for the support ribs were made using a saw blade.
At the bottom right of the picture, there is extra material that acts as a holding tab. This tab allowed the part to be securely held in the vice while cutting the contour and slots. It was later removed using a large face mill.
All the cheeks plus two spares. You never know what mistakes might be made in the following production steps.
The supports are inserted and soft-soldered.
After soldering, a hacksaw was used to trim them...
... and a file to finish them.
Job done; horn cheeks are ready for assembly on the frame.
Positioning them in the correct position with the aid of a vernier caliper and a set of gauge blocks.
The pre-drilled holes in the horn cheeks act as guides for the holes in the frame. It's a quick and dirty way to locate them.
Once fixed with two or three screws, the remaining holes were drilled.
But even this method of locating the holes works fine.
Holes for the spring hangers, brakes, and angle profiles were set out using the milling machine and its digital readout.
The horns are completed and fixed to the frames.
These spring hanger parts were made on Toin's 4-axis CNC milling machine.
