Practical Engineering

The boiler cladding is made up of two brass outer sheets and 1/32" balsa wood as insulation. The balsa wood is cut into 3/8" wide strips. To ensure the cutouts in the brass fitted around the cylinder block, spectacle plate and water pump pad, two cardboard templates were made. The brass also had a joggle set to help the 3/16" overlap in the top and bottom seems. Once the templates fitted the boiler the cutouts were transferred to the brass sheet and milled and with a light file fitted to a snug fit. The templates were then used to cut the balsa wood (see photos)

Cutting balsa wood into 3/8" wide strips

Tape used to hold the balsa wood in position and the template used to set position of tape

3/8" strips stuck in position ready for template to transfer cutouts

Marked out, then cut with knife

One side of the insulation cut to size and shape

Trial fitted into rolled brass outer cladding

Trial fitted around 2,1/2" tube to check fit of joggles

Boiler bands in place also to check fitment

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