Hanger bars and "Black Iron Butterfiles"

[e57]

Anyone know of a good hanger bar for use with what I reffer to as "Black Iron Butterflies"? - You know the type normally suited for use the lathers channel or 1/2" conduit. Trying to get a fixture like this to sit with a 1/16" toloarnce - and SOLID in wood framing...

http://www.kurtversen.com/Catalog/Leafs/Section_T/T4220.pdf