I could then hold the furnace part by the outside to bore out to the required diameter, face the end and cut a short spigot to locate it into the lower half.

A 4mm wide slot was milled across the top for two lugs that will need to be soldere don and I then made use of the slot with a piece of key steel slipped into it so I could set the slot horizontally while I bored out the hole for the flue.

I then rotated it 180deg so that the fire door opening could be milled on the opposite side as well as some small pockets to locate the hinge and latch parts that would also be soldered into place.

The furnace on these engines has quite a lot of wording cast into it and I was keen to replicate this so drew it out in CAD and used the CNC to mill away the surrounding metal to leave the letters standing proud, This took quite a while as the fine pointed engraving tool could only take a small stepover but it's tapered end did replicate the cast letters draft angle.

The furnace body was then held on the rotary table so that a pocket could be milled into which the suitable bent lettering could be soldered

The lower part of the furnace was base from some square bar, first boring out the waste material and a step to locate the spigot of the top half.

Then over to the CNC to cut the outside complete with draft angle to the sides and feet.

Then flipped the other way up to square up the cavity before milling off the excess depth.

I used a Sif type rod to braze the two main halves and the hinge/latch parts together then after a quick pickle used silver solder to do the nameplate and top lugs.

After a clean up and grit blast and the addition of the door that's about complete.