An awful lot of work goes into the NGV assembly and since it involves a lot of cutting, bending and welding of thin stainless steel parts, at each stage the stakes get higher.
The penalty for a mistake is hours of work reduced to twisted scrap in a microsecond.
But that's half the fun isn't it?
Here's a shot of the inner and outer rings of the NGV. The curved blades have been inserted into slots cut in the inner ring using a jigsaw.
(I removed the footplate and used it freehanded as a reciprocating saw. Nasty, juddery experience, but it worked)
The NGV assembled and ready for final welding. The central web has just a small hole in it at the moment, that will be opened out to provide location and support for the turbine shaft tunnel
I discovered it's more than normally important to work slowly, tacking the parts together at opposite diameters and letting it cool after each weld to avoid the assembly distorting.
The first time I made one of these I only just got away with it. The turbine housing (outer ring) finished so far out of round I amost didn't have enough thickness of metal to true it up.
Since the turbine wheel itself is supposed to howl round in that bit of pipe with a clearance of just 1/4mm (10" thou.) It's vitally important for it to be absolutely round and concentric with the shaft tunnel support.
This time, I checked the alignment in the lathe chuck after each tiny tack-weld.