I took the liberty of moving this topic to the woodturning section. Gareth, you ask very good questions. If by chance, you do not already have the Tormek Woodturner's Information Box, I recommend it highly. It is, in my opinion, Tormek's best video and well worth the cost. Here is a link:
https://www.tormek.com/usa/en/accessories/other-accessories/tnt-300-woodturners-instruction-box/In addition to being an expert with the Tormek, Jeff Farris is also a very experienced turner. Jeff worked exclusively with the SG-250. (The other wheels were not available when he left Tormek.) One of Jeff's pearls of wisdom from the DVD is to reshape gradually. By that I mean if your skew left the factory not matching any of the Tormek presets with skew and bevel angles, do not try to regrind the whole change in one session. Just do it partway and leave the skew sharp. Get continually closer during the next sharpenings. You will soon be where you want to be and only need Twisted Tree's fabled less than two minute sharpening.
Twisted Trees and Rich Colvin both have much more extensive turning experience than I do. I would make only two suggestions. The first is the gradual change I just described. I have experienced what you are going through. An interminally long sharpening time is totally frustrating. Even a small amount of reshaping can be frustrating. Do it in small bites. Do not be afraid to use lots of pressure with your SG wheel.
The second suggestion is to keep your TT-50 convenient. It will make your grinding wheel cut faster than just your stone grader. Use the TT-50 and when the stone starts to slow down, switch to the stone grader. Go back and forth as needed.
Once you have the shape duplicated, TT hit the nail on the head.Sharpen often.......
Keep posting.
Ken
PS Jeff's other pearl of wisdom was if the shape you want is radically different than your present tool, buy a tool shaped as you want it. This is especially good advice if you decide you really prefer the original shape.
