Resurecting a B&S rack milling attachment linear dividing unit.

The job is done by gearing the table screw shaft to the dividing head input shaft, so that the dividing head rotates while the table is feeding, this at a ratio that provided the desired lead for the spiral angle of the gear to be cut. The table of the mill is then swiveled to match that spiral angle, and the teeth cut, one after the other.
With the pair of gears cut, the spiral lead was 4X on one than the other, making it necessary on the one with the shortest lead to use the short lead attachment, and because the table will not swing to such an extreme angle, to use the universal spindle attachment (call it a vertical attachment, but it swivels in all planes) to drive the cutter rather than the main (horizontal) spindle. If you can find a copy of B&S book, "Practical Treatise on Milling and Milling Machines" there are illustrations showing these setups.
 
My go-to copy that I have owned since 1964 is in the process of being rebound by DH, one of his many diverse talents; it has many pages, especially in the tabular data that are afflicted by "mechanic's tan". It is well used to say the least; it was one of several reference books required for our after hours apprentice classes.
I'm sure that as with many other things, it is easier to ask for forgiveness than permission --- I only ever asked and was granted permission to post an article from American Machinist regarding niter bluing, it was posted on HM some time back.
 
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