Shay Vings wrote:
I had a go at a DIY version based on mdf quadrants fixed to a nova scroll chuck jaws but I wasn't very happy with my efforts.
I didn't drill the holes for the button screws as accurately as they should be. Also the rubber material I used for the buttons was too soft and not truly cylindrical. Both these factors meant the concentricy of the bowl when fixed in the "jaws" was poor. I found the whole exercise disappointing but I must try again sometime as the bought jobbies are very pricey. Meanwhile I use jam chucks or flat discs with router mat, provided I remembered to make a cetnre mark on the base earlier!
I don't think it's just you!
From the Q and A in the article linked......"It didn’t run very true, but I only turned the very bottom down, I didn’t go up the side at all. I was able to sand it pretty well at slow speed."
Few solutions with soft, flexible buttons are going to be suitable for anything but flattening the bottom.
The other 'small' issue with these arrangements is when you are turning towards the limit of the lathes diameter capacity in the first place - if you are planning on reversing with such jaws you need to plan your pieces diamater carefully.