I went to one of the 'better' lumber suppliers in my area this afternoon to get a 1 3/4" dowel as part of my pepper mill project. The 'boss' of the outfit said he'd turn one for me on a duplicating lathe; $20 for 3' of Red Oak. Twenty bucks is a bit much (to say the least) for 3' of dowel, but I felt I would get the most accurate dowel and make assembly of the mill a piece of cake. I count on have a very snug fit and would sand to a diameter that allowed the snug fit after glue up.
After cutting, he walks in with the dowel and I check for a nice snug fit in my 1 3/4" bored mill. Fit perfectly ... for about 1" on one end, the rest was tapered 1/8" to 1/4" too thin (in diameter).
Of course it didn't help when he said "close enough". He knocked $15 off the quoted price, but I said to him "there is nothing more expensive than a piece of wood you can't use".