[AdamMarkon]

Hello. There is a question to the millers - in which direction do the left cutters rotate? If the milling cutter with the direction of the grooves on the right rotates to the right, then the milling cutter with the grooves on the left rotates in which direction? Left, or right?

[deadlykitten]

hy it's possible to have the toolholder/endmills with groove/flutes straigth, to the left/right, and all those combinations will use same spindle sense

there is no conection between spindle sense and flutes direction, thus a right tool, classical one, may have different flutes/groove geometries

in common language, a left tool requires an opposite spindle sense, while a rigth tool uses the default spindle sense

a right tool, with :
... z flutes/grove has the tendency to pull the material&chips up, and also it tends to get out of the collet
... s flutes/grove has the tendency to push the material&chips down, into fixture, and also it tends to go dipper inside the collet
... straight flutes/grove has no tendency whatsoever

for example, think of a tap : the one for blind holes has different flutes direction in respect to another for through holes

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endmills ( cuting on side ) or reamers ( conical ) with s/z flutes : one has the tendency to smooth out cutting, while the other makes it rough, thus one tool can be more/less stable, depending on how the flutes orientation is ( + how many teeth in cut, etc ); the difference, is that cutting starts near the tool shank, while for other, cutting starts near the tool edge / kindly

[Superman]

You make it bloody hard, Deadly

L/H cutters run in a CCW direction, uses M4 (opposite to a R/H cutter M3)

The idea was if you created toolpaths for a complicated R/H part using conventional tooling (ie. a climb mill operation), you could mirror that toolpath and use L/H cutters, you would be still be climb milling... Hole drilling operations wouldn't need reverse paths, just mirrored positions.

[deadlykitten]

hy super i think it looks "hard" because i tried to diferentiate between spindle sense and grooves direction

nowadays a common left endmill would have flutes in opposite direction in respect to a right endmill, thus for most tool users, there is a "default" association between spindle sense and flutes direction

but from a tool design point of view, there is no such association; demand for reversed helix has dropped considerably

[TomJacks0n]

Ohw..is it really too hard?