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Author Topic: Proper directions of X, Y, an Z axis  (Read 5997 times)

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Proper directions of X, Y, an Z axis
« on: February 27, 2014, 11:19:08 AM »
I'm very new to machining and am finally starting to set things up and want to do them properly.  What I have learned is the tables are X and Z and the mill spindle vertical is Y.  I need to know proper directions + and - for the three axis's.

I read a post once where the gentleman said the cutting direction is normally negative.  Looking at Y, extending the mill into the work I would expect to be -Y.  Now for X and Z I'm not sure.  If my lathe head is left, and I'm cutting from right to left, is that considered -X and if the tool is going from being on my side of the work, to going away from me, is that considered -Z?  

Any advice would help me set this up properly.

Thanks,
Ed  (TeaMan)

Offline Fastest1

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Re: Proper directions of X, Y, an Z axis
« Reply #1 on: February 27, 2014, 11:34:35 AM »
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)

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Re: Proper directions of X, Y, an Z axis
« Reply #2 on: February 27, 2014, 12:04:52 PM »
It is also known as the "Right Hand Rule". A little more on its explanation. He is a little slow to get started but informative just the same.

https://www.youtube.com/watch?v=mBhE8Mbkj1A

Btw, Z- is cutting into your work, whether lathe or mill.
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)
Re: Proper directions of X, Y, an Z axis
« Reply #3 on: February 28, 2014, 10:44:08 AM »
Thanks Fastest1.  This explains the coordinate systems, but I guess I'm still a bit confused.  I was corrected before that the X and Z axis are the table planes and the Y is the vertical plane.  Looking in Mach3 turn, it solidified that in my mind because it only has X and Z since the lathe only has the table movements.  The Cad reference you showed here, even on a mill on the first link shows it the way I am used to picturing it where the X and Y would be the flat plane the tables move on, and the Z the vertical plane as the first link shows on the mill.  That is why I wanted to pose this question once more here to ensure I had it engrained in my thick brain before I set my machine up.  I know that with a home machine, I can do it what ever way I want and make it work anyway I want.  I'd rather do it in a standard way, or the most standard way in machining so when I get into conversations with someone who works in the profession, we don't have to spend the first part of the conversation getting on the same page.

Looking at the first link you presented, it's obvious that there is more than one way the profession views the axis, or is it different between the lathe and the mill?  Right now I have my DRO plugged in so it matches the mill in your first link and I only have used it that way for a very short period of time, and only to do some minor things.  I was hoping to fix it now, so I'm learning it "right" if there is such a thing.

Again, I thank you for answering this question.  Now I'd ask for clarification on a couple things, such as which axis is which, and when looking at the lathe spindle, moving the tool toward the chuck, is that "-", and moving it from side of the machine I stand on to the opposite side of the machine, is that also "-"? 

My objective here isn't to start a debate.  I just want to do it "right" the first time, and continue this pattern.

Again, many thanks
Ed (teaman)

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Re: Proper directions of X, Y, an Z axis
« Reply #4 on: February 28, 2014, 11:06:59 AM »
   I dont believe there is a correct or standard way as you can see from the different articles. I am just a hobbyist and am wrong plenty often, the terms I have always heard are that the Z is spinning, whether tool or part, mill or lathe (this is not always true as there are A & C axis too). The - direction is always into the work. Z- would be cutting towards the chuck (or into the table if a mill), X- is the tool traveling towards the center of the piece.

   That all being said. I dont think it makes 1 bit of difference as long as you the operator understand how you have it set up in CAD, CAM & how the machine is configured.
« Last Edit: February 28, 2014, 11:08:52 AM by Fastest1 »
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)
Re: Proper directions of X, Y, an Z axis
« Reply #5 on: February 28, 2014, 11:43:41 AM »
Makes a lot of sense.  Your explanation of the rotating part of the machine being Z, makes sense as to why the lathe could look different than the mill, where the lathe spindle is in the same plane as the table and the mill spindle is perpendicular to it.

You said you were a hobby machinist, understand, I'm not even at that point yet, so I'm very grateful for all explanations.  Eventually it'll make sense in my mind and I'll execute on it.

Glad you posted that explanation, it definitely put that aspect into perspective.

Thanks
Ed
Re: Proper directions of X, Y, an Z axis
« Reply #6 on: February 28, 2014, 12:21:07 PM »
If you are using Mach, imagine standing in front of your mill looking down at the table.  The table is like a piece of graph paper, positive X to the right and negative to the left, positive Y away from you and negative towards you.  The head goes up and down on the Z axis, positive being up.

If you dial in a positive X movement the table moves to the LEFT, so that the "control point" which is the tip of the tool held in the spindle, moves to the RIGHT relative to the table.  Similarly if you dial in a positive Y movement the table moves towards you.  If you dial in positive Z the head moves up, away from the table.

For all practical purposes, you can set the "zero" of the XY coordinate system at a convenient point on your work, for example at the "bottom left hand corner".  I tend to set the Z zero at the table surface as I have an automatic setting gauge for that; and measure the height of a convenient reference part of the work.  Another way is to set the Z zero at the work surface.  In either case, as the tool moves into the work Z decreases, and if you have set Z at the work surface, it cuts at "negative Z".

In principle you could label the axes differently, but for example the Mach wizards and at least the CAM program I use (G-Simple) use the above definition so you could get in trouble!

 

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Re: Proper directions of X, Y, an Z axis
« Reply #7 on: February 28, 2014, 02:16:21 PM »
Glad I could help. Btw, You are now a hobby machinist until it pays the bills.
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)
Re: Proper directions of X, Y, an Z axis
« Reply #8 on: March 01, 2014, 10:28:07 AM »
If you are using Mach, imagine standing in front of your mill looking down at the table.  The table is like a piece of graph paper, positive X to the right and negative to the left, positive Y away from you and negative towards you.  The head goes up and down on the Z axis, positive being up.

If you dial in a positive X movement the table moves to the LEFT, so that the "control point" which is the tip of the tool held in the spindle, moves to the RIGHT relative to the table.  Similarly if you dial in a positive Y movement the table moves towards you.  If you dial in positive Z the head moves up, away from the table.

For all practical purposes, you can set the "zero" of the XY coordinate system at a convenient point on your work, for example at the "bottom left hand corner".  I tend to set the Z zero at the table surface as I have an automatic setting gauge for that; and measure the height of a convenient reference part of the work.  Another way is to set the Z zero at the work surface.  In either case, as the tool moves into the work Z decreases, and if you have set Z at the work surface, it cuts at "negative Z".

In principle you could label the axes differently, but for example the Mach wizards and at least the CAM program I use (G-Simple) use the above definition so you could get in trouble!

 

Hey John.  Do you use Mach3 turn as well as Mach3 Mill?  From your description it follows what Fastest1 said where the spindle is Z.  So on the lathe in Mach3 turn, there is no Y since the spindle is in Z.  The table that goes from you to away from you as you stand in front of the machine is Z, where on the Mill, the table the goes from you to away from you is Y.  On my machine, that is the same table, which is where my confusion comes from.  I have a 3 in 1 machine with mill and lathe in one machine and have DRO on my machine.  How do you handle the same tables going from having a Y axis on the Mill and changing to a Z axis on the Lathe?

Thanks
Ed

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Re: Proper directions of X, Y, an Z axis
« Reply #9 on: March 01, 2014, 10:47:42 AM »
I believe it is a feature called "axis swap". Never used it or really read up on it. I think Hoss used it a bit when using his mill as a lathe. I would likely just have 2 profiles for the different processes.
I want to die in my sleep like my grandfather, not like the passengers in the car! :-)