The Waineo design is a variation of the Elgin machine. The machine grinding machines do decrease the amount of work that the individual has to do and limits that work to the lifting of the mirror on and off of the tool and applying grit to the grinding. In a professional situation this makes the productivity of a worker a lot higher. This doesn't mean that a grinding machine of any design isn't an appropiate device to own. The latest issue of Amateur Telescope Making Journal has another Elgin grinding machine design with some nice pictures. The units can be built for less than $100, depending upon how much you can scrounge and how much you have to buy retail. For scopes over about 14" or so, the effort to push glass becomes so high that you get very tired very quick and the grinding machines become rather necessary to make the larger mirrors. As far as doing a 6" refractor, one of the big things that you have to do is insure that you don't have any wedge in the lenses. Newport Glass has some articles on doing lenses on it's website. You are going to spend as much as 40 hours or even more doing each surface by hand. Machine grinding will reduce the working time by a bit but you will spend a lot of time watching the machine work (professionals run several machines together and have auto feeding of the grit) rather than actually doing the work youself so it's a bit of a wash as far as time is concerned. Either way, if you start getting any wedge into the glass, you're going to spend the time hand working the glass until the wedge is taken out. If you plan on grinding a lot, I would build a grinding machine and have fun with it but remember that it isn't the be all and end all thing to have for making telescope optics.