Putting together a bok

[carcinogen]

I'm a homebrewer who got into pot distilling last year, and now I'd like to build a column still. Years ago I built my ideal homebrewing setup which involves a half-keg (15.5gal) with a hole cut out in the top, a drain spigot, and a 4500W heating element inside controlled by a PID temperature controller with pulsewidth modulated manual controls. It works wonderfully for homebrewing and I'm thinking that it would make a pretty good boiler for a column still. I also have a counter-flow chiller (25 feet of 3/8" copper inside a garden hose) that doubles very well as a worm for distilling.

After doing a great deal of reading I've settled that the bokabob 2-plate design seems to be the easiest, cheapest design advocated by people on this forum. My chief concern is sizing--I don't want it to take 10 hours to reflux 10 gallons of wash into ethanol. Would a 2" column with 48" of packing then be insufficient? Are there diminishing returns realized by stepping up to a 3" x 60" column, perhaps? Would a VM run faster than an LM?

Would my counter-flow chiller be better put to use in a VM still or otherwise? As far as I understand, the LM doesn't -require- a condenser, although the distillate comes out hot.

Do any of you have any insight before I drop big bucks on a length of copper pipe? Normally I'd just go ahead and do it but it looks like the copper is going to run me into the hundreds of dollars, so I'd like to be cautious and careful.

[Kentucky shinner]

I have run a 48"- 2" bok with 6 gallon of low wines and it is not uncommon for it to run for 8 -9 hours. So if your wanting to run 10 gallon in 10 hours I am pretty sure you need to go up to at least 3".

[rad14701]

Getting your boiler up to temperature accounts for part of the time you'll invest... Take that time out of the equation and you can conceivably have double the take off rate from 3" versus 2"... And 10 gallons of 10% wash would provide 1 gallon of neutral spirits... A take off rate of 2 liters per hour would mean that you'd need 2 hours to deplete all of the ethanol from the wash... I'm pretty sure there are a few 2" columns that are capable of the take off rate... I regularly pull 600ml - 750ml per hour with a 1.25" LM reflux column from a 12% - 14% wash...

[Kentucky shinner]

You could could do that with a 10% wash easy. I only used mine for spirit runs.. 6 gallon of 45% ABV takes a while if you do it right. I normally ran 95%ABV take off. I would take off 1/2 gallon an hour usually end up with 2.5 - 3 gallon. thats almost 6 hrs running time. Not including warm up.