If it works, it works. I had to true 6 jaw glass lathe chucks in the past, the main jaw set was held with a ring at the back of the glass gripping replaceable inner jaws, line ground to true the replaceables they'd be fine, until someone got the torch or main burner too close and distorted them again, our newer glass chucks have one piece jaws, so if overheated it's a whole lot of money to sort those...