Are these only for use on stock that's the same width as the blades, or can it be reliably used to plane down something as big as 12" stock? I need to plane a 12"x18" 2/4 piece of stock to 3/8" thick and all of the wood stores in town I've talked to won't do it unless I buy the wood from them and I already have all the stock I need.
I don't have much money, so I figure I can put it to better use purchasing a good quality portable planer as opposed to a very cheap 12" planer. Any advice is appreciated. Thank you.