Bright EN24T steel vs Black EN24T for cutting gears

[Nigel Graham 2Participant @nigelgraham2]

A thread I'm looking at because I'm wondering whether to cut my own gears or modify stock ones for my project, since Edwardian trade magazine review photos are not exactly accurate works drawings so something that respects 1908 practice is near enough. (The originals were "machine-cut steel" though – it says so in the contemporary publicity material!)

Not Done It Yet _

Not sure where the "climb milling" comes from here, unless as being not sure of what Andrew Johnston's earlier comment meant about the cut being from "inside " the material.

Assuming horizontal milling, or the vertical-mill equivalent using a gear-cutter on a stub mandrel, for down-cutting the teeth approach the side of the blank and cut outwards or up (!) towards its circumference.

Look at Andrew Johnston's photo. If we assume the cutter is revolving anticlockwise as we look onto the machine: for down-cutting the table would therefore move leftwards (away from the camera). So each tooth, below the spindle axis so moving rightwards, would enter the blank's face remote from us and emerge up through its circumference.

If the cutter revolved clockwise for the same left-going table-travel, clearly that would be climb-milling, with the active teeth and table moving in the same direction. As you say, not for the relatively light-weight machines and accessories most of us possess.

I would be surprised if industrial gear-cutting by horizontal profile-milling rather than generating by gear-shaper or hob, would normally have been done in climbing mode, except perhaps for finishing cuts, but if someone knows otherwise…

[not done it yetParticipant @notdoneityet]

Thanks, but I do know the difference between ‘conventional’ and ‘climb’ milling. My query was a simple one. I most certainly use conventional milling when cutting gears with involute cutters on my machine. Not yet tried hobbing gears…

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