I understand the principle of using a universal dividing head in order to mill helixes (eg. helical gear teeth, spiral flutes) and basically how they are set up; they are driven by the table's feed mechanism to provide simultaneous linear and rotational motion to the work at a given ratio.
From what I've read, most milling machines have optional accessory dividing heads whose drive input is designed for that machine's specific feed mechanism. I have a Hardinge TM (plain non-swiveling table) milling machine with no power feed. I know that Hardinge made a dividing head for the TM and UM millers that have power feed. WAY too expensive and hard to find for my budget. I see also that there are third party (eg AccuPro) universal dividing heads on the market. My question is, how do these third party dividing heads get their drive from millers of unknown manufacture? Or to be more specific, how would I drive one of these dividing heads on my miller with no power feed?