mine are only 7x14 lathes . They are so cheap to buy that getting a local grinder to grind them would cost the same if not more than the lathes cost . Plus they work as they are so no grinding needed .
I did take them apart and deburr and do some polishing though when I bought them . If I do any work to them I'll modify them to use linear slide which I already have on hand , and I am considering it . As I mentioned , I get a few tenths taper which I just modify the program to compensate . 5/8 aluminum with no end support being machined down to 1/2" with a stick out of 3.5 inches is going to be prone to some issues on the best of machines , at least the taper is consistent since my parts need to be within .0005"