Who labelled the X and Y axes for DROs on lathes and mills?

I will repeat the facts for anyone unclear on the subject.

On a milling machine there are (typically) three axes of movement: table left/right and forward/backwards, and head (or quill or knee) up/down. A Digital Read Out (DRO) labels those axes X, Y and Z. X for left/right, Y for forwards/backwards and Z for up/down. This makes a lot of sense if you think of a graph laid in the table as the DRO axes all agree with the nomenclature for a graph's axes.

But with a lathe it all goes askew. On the DRO the Y axis is the main left/right movement along the bed, and X is the cross slide into and away from the rotating work. Why is it not the other way round to match our piece of graph paper?

Someone, or some organisation, or company presumably set these labels when DROs became available, and was this in the 1960s? Or had machine tools already been given axis labels earlier in the 20th century?

I have tolerated this for many years but feel it is finally time to see if anyone knows who labelled the machines' axes? and why? For extra amusement we could discuss the polarity of the axes (plus and minus directions) but I won't complicate things.

Norm

The spindle axis is always Z. The others follow from that.

See:

https://www.cnctimes.com/editorial/axes-convention-on-cnc-hmcs

There will not be many people on this forum who have a lathe with a Y-axis.

Who labelled the axes for DROs on a lathe as X and Y? You did.

The correct convention is Z and X.

The Z axis is towards and away from the spindle. The X axis is the lateral movement, at 90* to the Z axis.

A lot of 2 axis consoles sold as suitable for lathe & mill have X & Y printed on the buttons so the user can't be blamed for that.

Can't you just swop the Encoder plugs over?

Norm,

I think, as you suggest in your question that the axes were identified way, way before the modern DROs. I dumped some very old workshop manuals a good few years ago and I am sure the axes were identified then. My guess is that it will go back well before WW1 when they had semi automatic machines and probably way before that. Whether the DROs for lathes follow the old labelling, I am not sure.

Phil H

My Warco lathe is incorrectly labelled with X and Y and I need to change it when I get round to it. Z definitely the axis through the spindle.

Tony

Absolutely outrageous

Norm, if it bothers you then you can get ones where the axis is part of the display so can be changed at setup. Though I expect most people except it as printed X&Y on their Sino etc rather than spend £1100 on a Newell console that allows it to be changed.

Here's an idea:

Print out a load of uppercase Z's in various sizes and fonts. Arrange them on a page, send to Neil. Win £30.

Make them white text on a black background and resubmit the following month to double your money.

£0.10 bonus if you include a perimeter dotted line and the pair of scissors from your wingdings font.

The display box for my Warco lathe has three axis displays, labelled x, y, and z starting from the top. I could plug the cables into the appropriate sockets to have y and z active, but it looks silly with the top box blank so I use the top two with the topmost one, labelled x, displaying z, 'cos I find that the most convenient. It's therefore completely wrong, but since I don't look at the labels, it really doesn't matter.

I don't worry about it and just get on with the work at hand. Life is much too short for anxiety on axis designations.

I like that

You could probably drag it out for another £30 by sending in some up/down and sideways arrows for those that can't remember which letter is which axis

CNC pipe bending machines use YBC. The vertical rotation is the C axis, just the same as it is on a milling machine since C is rotation about the Z axis. The feed of pipe into the bend head is the Y axis and the rotation about the Y axis is the B axis (plane of bend). It is a convention that matches CAD, and mathematics as well when drawing graphs. 3D graphs have the relative orientation of the Z axis to the XY plane the same way round as machine tools. 3D graphs possibly preceded machine tools and the convention used for these graphs could then become the norm for machine tools to avoid confusion.

Martin C

So there really should be a prize for the first person to have a Y axis readout on their vertical slide

😋

Just to add to the confusion, for CNC threading on the lathe (at least in Mach3), the conventional threading direction is labelled "clockwise" - did you ever see a lathe chuck rotating clockwise when threading an ordinary thread? Apparently this is because the lathe CNC axes are derived from the mill by laying the mill over on its left hand side and the mill spindle of course rotates clockwise viewed from above by the operator.

Not sure why that is confusing John, the controlled point that is the tip of the threading tool is rotating clockwise relative to the work.

regards Martin

There are industry standards for naming axes of travel. Here is one reference I found.

**LINK**

You can use what ever you like, as long as you know the direction that the axis readout means. In my case I have them the same as the commercial stuff at work. That way you don't accidently move the axis in the wrong direction.

Towards the chuck or spindle should be Z minus on a lathe. The direction to the centreline of the spindle should be a decreasing number. From the spindle centreline , set at Zero, all values away from the centreline should be positive.

I have seen and used lathes where the normal conventions are not adhered to. Like on one lathe I used, X was the axis inline with the spindle, (Normally Z), and the values to the spindle were positive. The in the Y axis(Normally X) any value to the centreline was positive. Moving away from the centre line was negative. The complete opposite to the normal conventions. But the readout was only and XY two line readout. Yes it work, but confusing as hell for me to learn. To the chuck was positive ,because the depth micrometer increased with the amount being cut. also when he used a long (4 inch stroke DTI) as the carriage travel was towards the indicator , it got greater. So as a result, when the digits were installed etc, he made them read the same way that he had been using the machine since it was new.

Although you can set the thing up as you like you could get into problems if you want to use some of the functions like ARC on the mill or if you want to set a finished diameter as zero on the lathe in which case the readout will count down to zero as the tool is advanced with +ve handwheel movements.

So if you are fitting one from scratch then best to do it to convention rather than getting used to using it another way and then having to learn again when it has been altered to use the functions as that is bound to lead to mistakes.