I can't believe it's been over a month since I last wrote a post. I had everything ready to write a new post on another attempt at turning a chimney and then my enthusiasm for modelling suffered a bit of a blow. No I'm not talking about the referendum (although as the result directly affects my job which I might well loose within the next 18 months it didn't help) but some rather public feedback on my modelling. I'm still figuring out if I want to talk about it, but having been away on holiday (which included a railway related day out) I'm feeling a bit better and so on with the story.
Last time I'd managed to turn two chimneys neither of which were usable; one broke and one didn't have the right profile. The third attempt basically followed the same approach as the first two, but once I got to finishing and drilling out the turning I switched from the 3 jaw chuck to using a new purchase; a ER16 collet chuck. The chuck is a genuine EMCO part but the collets themselves are cheap Chinese parts; the entire set cost me less than a single collet often does and they seem accurate enough.
Unfortunately I forgot to take any photos while actually using the collets but, as I said before, the approach was the same as last time, just with a different way of holding the parts. Once I'd turned the chimney (photos of it on it's own appear not to have been taken) I moved on to preparing the body casting by removing the old chimney and drilling a mounting hole.
This involved another new addition to the Unimat 3; a milling table. If you remember, I previously had to hold the casting using the 3 jaw chuck which wasn't particularly stable or safe. I started by extending the existing hole in the chimney down a long way using a drill of roughly the same size to help ensure it was vertical. I then cut the top part off the chimney off with a razor saw and tided up the casting before opening out the hole ready to take the turning.
With the casting prepared it was easy to simply slot the turned chimney into place.
It's not a perfect match for the drawing I have but it's very close (close enough for me at least) to a number of old photos of Tallylyn and more importantly I'm much happier with the turning than the original cast version.