# Thread: 4th Axis Direction Question

1. ## 4th Axis Direction Question

Can you folks with a Tormach 4th axis tell me which way your axis moves when you do a positive axis move. This would be as viewed from the end of table which the chuck faces. CCW or CW?

Thanks

Jeff E.

2. My brand new rotary table moves CCW looking at the chuck with a positive A move. Not sure if it's right or wrong, but I think it's right since it matches the engraved marks on the side. Hope that helps.

3. Thanks Dan,

I believe that yours is correct. Mine (2 years old) was set up the opposite way because the marks on the table itself were positive CW an negative marks were CCW. Guess if it was mounted on the right side the marks would be correct :-) Anyway I recently changed it to operate like yours.

Thanks for you response

Jeff E.

Descriptions for A axis direction are often confusing.

I find the Right Hand Rule to be the best way to describe it. Makes no difference which way your headstock is mounted or where you are looking from.

Take your right hand, make a fist, point your thumb in the positive
direction of an axis, the direction of your fingers gives you the
positive direction of rotation around that axis.

Greg

5. For the record: Is that the direction the axis rotates, or does it represent the tooltip motion relative to the axis as it rotates?

6. Originally Posted by flick
For the record: Is that the direction the axis rotates, or does it represent the tooltip motion relative to the axis as it rotates?

Flick,

It is the way the axis rotates.

Jeff E.

7. I was actually hoping for a reply from Greolt. He seems to speak with some authority, and notes that many descriptions of rotational axis motion are confusing, and then provides an incomplete description himself.

So we're supposed to think of linear axis motion in terms of tool movement, regardless of whether it's actually the tool or the work moving, but we're to think of rotational motion in terms of part movement. Suppose this still applies if your rotational axis is actually implemented as head motion?

I've arbitrarily declared my rotational axis motion to be positive and negative in terms of relative tool motion in the same directions that Y is positive and negative as seen from the operators normal point of view, looking down on the work at the near side of the rotational axis. This happens to correspond to Greolts description of the right hand rule, if he was indeed referring to work/axis motion, as opposed to relative tool motion.

Unfortunately, this means that the Mach simulation is backwards, as is the engraving on the rotary head. I'm planning to engrave another set of numbers next to the original, and fill them with black paint, while filling the original with red, but I don't know what to do about the simulation...

8. Originally Posted by flick
I was actually hoping for a reply from Greolt. He seems to speak with some authority, and notes that many descriptions of rotational axis motion are confusing, and then provides an incomplete description himself.

So we're supposed to think of linear axis motion in terms of tool movement, regardless of whether it's actually the tool or the work moving, but we're to think of rotational motion in terms of part movement. Suppose this still applies if your rotational axis is actually implemented as head motion?

I've arbitrarily declared my rotational axis motion to be positive and negative in terms of relative tool motion in the same directions that Y is positive and negative as seen from the operators normal point of view, looking down on the work at the near side of the rotational axis. This happens to correspond to Greolts description of the right hand rule, if he was indeed referring to work/axis motion, as opposed to relative tool motion.

Unfortunately, this means that the Mach simulation is backwards, as is the engraving on the rotary head. I'm planning to engrave another set of numbers next to the original, and fill them with black paint, while filling the original with red, but I don't know what to do about the simulation...
Sorry for the reply - I now feel so insignificant

Jeff E.

9. Originally Posted by flick
I was actually hoping for a reply from Greolt. He seems to speak with some authority, and notes that many descriptions of rotational axis motion are confusing, and then provides an incomplete description himself.

So we're supposed to think of linear axis motion in terms of tool movement, regardless of whether it's actually the tool or the work moving, but we're to think of rotational motion in terms of part movement. Suppose this still applies if your rotational axis is actually implemented as head motion?

I've arbitrarily declared my rotational axis motion to be positive and negative in terms of relative tool motion in the same directions that Y is positive and negative as seen from the operators normal point of view, looking down on the work at the near side of the rotational axis. This happens to correspond to Greolts description of the right hand rule, if he was indeed referring to work/axis motion, as opposed to relative tool motion.

Unfortunately, this means that the Mach simulation is backwards, as is the engraving on the rotary head. I'm planning to engrave another set of numbers next to the original, and fill them with black paint, while filling the original with red, but I don't know what to do about the simulation...
I think Greolt's answer was quite clear. If your 4th axis is aligned to the X axis, then point your thumb in the direction of X+, which will be to the right when facing the front of the machine. Your fingers will then be curling up and to the front, indicating the 4th axis positive rotation direction will be CW when viewed from the left end of the table, or CCW when viewed from the right end of the table.

Regards,
Ray L.

10. Uh Srsly? I didn't mean to offend, just trying to get greolt's attention so he might respond as well.

Here, maybe a dancing banana will cheer you up...

friends?

Originally Posted by Jeff E.
Sorry for the reply - I now feel so insignificant

Jeff E.

11. Ok. One more try. Do you suppose that "axis motion" as it relates to rotary axes actually refer to the motion of the workpiece, or the tool relative to the workpiece?

I fell into the trap of using axis and workpiece motion interchangeably in my own posts, but It's not really clear that they are the same. In fact, they might be interpreted as being quite the opposite.

Originally Posted by HimyKabibble
I think Greolt's answer was quite clear. If your 4th axis is aligned to the X axis, then point your thumb in the direction of X+, which will be to the right when facing the front of the machine. Your fingers will then be curling up and to the front, indicating the 4th axis positive rotation direction will be CW when viewed from the left end of the table, or CCW when viewed from the right end of the table.

Regards,
Ray L.

12. Flick,

The banana worked, I'm good.

Jeff E.

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