John,
I agree with you, axis designations are arbitrary. But in the world of machine tools, builders found it necessary to standardize the designation of axes in order to eliminate confusion.
The first machine tool builder guideline is, the linear axis that moves parallel to the "main" spindle's centerline is designated Z axis.
The second machine tool builder guideline that pertains to a milling type machine is, the longest travel axis is designated X axis. The remaining axis of a three axis machine tool is designated the Y axis.
I have done a bit of researching since this discusion began and there is a lot of info out there on the web that can shed more light on this subject if anyone is interested. The origins of the "Cartesian System" go back several hundred years and make interesting reading.
Dick
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--- In 7x12minilathe@..., John Kiely wrote:
Might I suggest Gentlemen, that your choice of X,Y,Z axes very much depends on the tools you use and your own personal perspective.
If you use a CAD package it might make more sense to follow?the XY&Z perspective it offers.
If you are a mathematician X would be Horizontal from left to right?Y your Vertical (Up Down) and Z your other horizontal of backwards and forwards.
I think it all comes down to your own personal preference and possibly the tool you use?
Ask any mathematician why they use XY&Z and they will tell you that they are just arbitrary values!
?
John Kiely (IRL)
________________________________
From: "anthrhodes@..."
To: 7x12minilathe@...
Sent: Wednesday, February 6, 2013 6:04 PM
Subject: [7x12minilathe] Re: Digital linear scale for 7x lathe?
Dick,
While I already knew this it can cause a great deal of confusion. For instance, if you have a horizontal mill with a vertical attachment and half way through a milling job you switch from one spindle to the other do you also change your references? Or on a combo mill like the Rockwell, where both axes are ready to go at any time, same question. You can probably find numerous other situations which create such confusions.
Even though I'm familiar with the "Z = spindle axis" concept, for non-commercial or amateur usage it's probably more useful to adopt the terms longitudinal, cross, and vertical, longitudinal being the long horizontal axis, cross being the short horizontal axis, and vertical you can probably figure out yourself.
I know that you can argue against what I've just said. One man's opinion. And by the way, on a vertical mill you may very well have two vertical axes, the quill and the knee, each of which needs to be treated separately. Yes, I know about X, Y, Z, A, B, C, etc.
Anthony
Berkeley, Calif.
In a message dated Mon Feb?4,?2013 12:57?pm (PST),?old_toolmaker writes:
On a lathe the long axis which is parallel to the bed is known as the z axis. This can be confusing because when you stand in front of a vertical mill the right to left axis is the x axis. Despite what may seem logical, the axis of the revolving spindle is the z axis.
The z axis on a vertical mill is the spindle axis, the z axis of a horizontal mill is the axis of the spindle.
OldToolmaker