Is there a 'standard' direction of rotation for horizontal mills?

[kwackers]

This is probably one of those questions that's either irrelevant or has no answer...

But.
I've just finished fitting variable speed 3 phase stuff to my H/V mill and wanted to make it so that 'fwd' on the switch made both the H & V parts rotate forward.
But as I was testing it I suddenly realised I don't know what or even IF there is a correct direction of rotation for an horizontal mill.
Now obviously you can fit the cutter either way round so presumably would fit it in whatever direction made the most sense for the job in hand but my question is:- Is there a 'normal' direction of rotation?
(It's sad, but I just want to be happy that when the switch is 'fwd' the mill is spinning in a 'normal' direction...)

[Lew_Merrick_PE]

Most arbor cutters are nominally set-up for an anti-clockwise rotation when you are looking straight into the body of the mill.  It's not as if you can't turn them around and cut the other direction, but that was the "forward" direction of rotation on all the horizontal mills I have run over the years.

The Hitachi-Seiki horizontal mill had a long lever to control the table feed direction.  If you lifted "up" on the lever while it was in a feed position, it put it in rapid traverse mode.  I was ganging parts on such a mill in 1970 with a $850 form cutter on the arbor.  As I turned away from starting the cut (I deburred parts while waiting for the cut to run), my apron caught on the feed arm and disengaged it.  I swung my arm to re-engage the feed and lifted it into "rapid traverse" mode -- with the parts less than 1/8 inch from the cutter.  I lost money big time on that contract.  I have a piece of that cutter epoxied around the keyhole on one of my tool chests to remind me about thinking through my actions...

[Davo J]

Hi,
My mill is set up the same as the vertical spindle. Being setup this way is good, because if you use a collet chuck with a end mill it will be going the right way.

Dave

[ksor]

My very old Vilh. Pedersen VPF-1 is running clockwise both vertical and horisontal.

It CAN run anti clockwise but it looks no good in the motor room when starting up anti clockwise mode because of the way the motor is set up - it tiltes/jumps a little too high I think.

So I think FWD is clockwise and is the "normal" direction on my mill.

[Stilldrillin]

If it is rotating the correct way for a twist drill. It is rotating correctly....... (Standard, forward, normal).

David D

[kwackers]

Looks like anti-clockwise it is then! (The twist drill thing is obvious - once you've thought about it...)
Thanks guys.

[Bernd]

Looks like anti-clockwise it is then! (The twist drill thing is obvious - once you've thought about it...)
Thanks guys.

This should be qualified by which end of the drill your looking at, wouldn't you think?

Bernd

[kwackers]

Pointy end poking out of the arbor...

[Stilldrillin]

Pointy end poking out of the arbor...

Unless it's for a flat bottom hole....... 

[djc]

Most arbor cutters are nominally set-up for an anti-clockwise rotation when you are looking straight into the body of the mill.

Which would imply that the force opposing the cutter's rotation is clockwise. Which would further imply that the thread on the arbor is right handed so that it is tightened due to cutter action, not loosened. Most full length horizontal arbors that I've come into contact with have _left_ hand threads... On the other hand, most vertical tooling that can be creatively and productively used in horizontal mode have right hand threads.... Most vertical tooling is also right hand cut.

The theory for horizontal mills is that the cutter rotation should not loosen the arbor nut, hence this is what governs normality.

Another aspect to consider is which side of the mill the controls are. You want the best view on the cutting pass; if your view on the return pass is partially blocked by the overarm and arbor, it's less of a problem.

[Lew_Merrick_PE]

My very old Vilh. Pedersen VPF-1 is running clockwise both vertical and horisontal.

It CAN run anti clockwise but it looks no good in the motor room when starting up anti clockwise mode because of the way the motor is set up - it tiltes/jumps a little too high I think.

So I think FWD is clockwise and is the "normal" direction on my mill.

Guys, if you look from the "pulley down" on a RH cut end-mill, then it is turning in a "clockwise" direction.  Look at it from the "bottom" (the direction you are looking in at a horizontal mill arbor) and it is running in an "anti-clockwise" direction.  If you place your head at the column of a horizontal mill and run the arbor in a RH-cut direction, it will turn in a "clockwise" direction.  However, that same arbor in the same set-up when viewed from the outboard support will be turning in an "anti-clockwise" direction.  It's all in your point of view.

The Right Hand (RH) cut direction is the direction of rotation you get if the thumb of your right hand is pointed towards the end of the cutter (as opposed to pointing towards the shank of the cutter) and your fingers sweep around as if you were grabbing the cutter.  The direction your fingers "sweep" is the direction of rotation.  This is a more accurate (and less prone to error) means of describing rotations.  The Left Hand (LH) cut direction of rotation is what you get if the thumb of your left hand is pointed towards the end of the cutter and your fingers sweep around as if you were grabbing the cutter.  Standard chuck/collet/toolholder integral shank cutters are RH cutters.

Arbor mounted cutters can be reversed on the arbor, so they have no intrinsic RH or LH configuration.  I misspoke on that before.  However, as I said previously, most cutters on a horizontal mill will appear to be turning in an anti-clockwise direction if you are looking from the standard working position into the column of the mill.