Welt cord is sized in 32nds of an inch. The most common welt cord is 5/32 and 4/32. The rule of thumb is to add 3/32 to the size of the welt cord to get the correct size welt foot. 5/32 plus 3/32 is 8/32 or 1/4", and that is the size welt foot to use on 5/32 and 4/32 welt cord. If you use 3/32 welt cord, you add 3/32 to get 6/32, or 3/16" which is the correct size welt foot for
3/32 welt cord.
You are correct that the size of welt cord you use is a personal preference.
No one lives forever, the trick is creating something that will.
Last edited by DanTwoLakes; 05-03-2012 at 10:31 PM.