What Size/Type Diamond Drill Bit and Grommet Will I need For HomeMade Glass Bong

I am making a glass coke bottle bong, because I believe it is bad for me to be smoking from a gatorade bottle with a hose pipe. I have a 15mm diameter stem, and want to know what size diamond drill bit I will need and what size grommet I will need, thanks.

If you got a dremel tool, get a silicon carbide conical grinding wheel (green in colour, cone shaped) it will work much better than a drill bit and alot cheaper.

Just a suggestion but if you have the stem and bowl why would you not shove that in the plastic bottle so your only heating glass or whatever, no reason you should be smoking some kind of hose(?) Anyway I know that's not what your looking for

5/8 inch is best if you wanna get a lot of good info check out soundrone on YouTube he does a lot of glass bong builds

I use bits like these: http://www.ebay.com/itm/10-pc-DIAMOND-HOLE-Saw-Core-Bit-Set-1-8-Shank-for-Dremel-Rotary-Tool-100-Grit-/360500309373?pt=LH_DefaultDomain_0&hash=item53ef7e2d7d

I drill flat glass in a baking pan of water with a dremel tool and a dremel press with those 1/8" bits(We use it for glass jewelry)

http://www.ebay.com/itm/Dremel-Rotary-Drill-Press-Stand-And-Work-Station-220-01-/260968587353?pt=Power_Tools&hash=item3cc2f0a059

Hope that helps