Chimney saddle, how to machine

[Scrat]

Hi,

I am restoring my Foden Lorry. The Chimney was completely rusted to bits so a new one was made.
The old brass end cap also fits the new one.
The big problem comes at the bottom end.
How do I machine a chimney base to fit the radius of the smokebox top?

Chimney OD at bottom: 43 mm
Smokebox OD: 177mm

The smokebox top has four screws to hold the Chimney base.
These form a square with 53mm between hole centres.

Can anyone help?

[Chip1e]

Hi I would try using a verticle slide in a lathe and cut the radius with a boring head. Or in a mill with a boring head. I have machined all my chimney saddles using this method but on a smaller scale only 16mm steam Loco's.
Regards
Paul.

[Old Man Aaron]

Aye, lots of ways you could fly-cut it.

[Scrat]

With my small MD65 lathe and the matching BFE65 mill I do not have much capacity.
The idea now is to make a dosk with a hole in the middle, bend it to suit the smokebox top, weld in a bit of pipe and then weld the tapered portion on top of it.
Looks ok on trial assemply.

Pics to follow.