Home Position

[bgpv2xt]

Not sure what direction to go in right now.
Marty on YOUTUBE "HOME SWITCH TESTING & HOMING THE MILL" at time mark 5:30 shows the table moving towards the base of the machine and Marty is calling it the minus direction.
However page 55 of the INSTALLATION MANUAL shows a Y with a plus sign going towards the base of the machine.
The machine is a V2XT Bridgeport and are trying to get the limit switches and home position figured out.

What is the position of the table when in the 0,0,0 position? From the operators perspective?
X The table is all the way to the right.
Y The table is away from the operator and closest to the base of the machine.
Z The quill is up as far as possible

So when X is increasing the table is moving towards the left.
So when the table is moving towards the operator and away from the base of the machine the Y is increasing.
So when Z is moving down the minus number is increasing.

As usual thankful for any help that comes this way.
Pat

[tblough]

On a mill, the direction is the apparent tool motion. So, even though the table moves to the left, the cutter is "moving" to the right. Home position can be wherever you want it. Normally for a knee mill, Z is homed as far away from the work as possible (Z+ movement), Y is homed as close to the operator as possible (tool moving towards the column Y+), and X is usually as far negative as possible (table all the way to the right).

https://centroidcncforum.com/viewtopic.php?f=64&t=3638

[bgpv2xt]

Oh boy ?????
So X and Z make sense. But Y is a question.
Does that mean that Y ZERO and Y HOME are the opposite ends of the table?
But X ZERO and X HOME are the same place?
And Z ZERO and Z HOME are the same place?

By the way I just noticed when a CNCM.HOM is processed the following movement happens.
X Minus. Table all the way to the right
Y Plus. Table all the way to the operator.
Z Plus. Table all the way up (retracted).

Pat

[cncsnw]

On any axis: Machine Zero = Home

Part Zero is different from Machine Zero. Part Zero can be anywhere you want to set it, and usually varies from job to job.

[tblough]

And, as I said, home can be wherever YOU want it. Most people prefer to have the machine Z as far away from the work surface as possible to prevent interference during homing. I prefer to have the table home as close to the operator in Y so that parts are easier to mount. The X axis is a toss up as to whether left or right is better. I'm left handed, so I like the table to the right and the cutter on the left.

Also, HOME does not need to be at the ends of the travel. You can home in the middle of the travel if YOU want. Once you set the home position, LIMITS determine the extent of movement in both directions in regards to the home position.

Once you set home and the limits of travel, you can then set multiple (depending on your software level) Work Coordinate System zero locations, and you can change those locations as often as you like.

[bgpv2xt]

Thank You All
So I think it should be set up so the
X is traversed all the way to the right.
Y is traversed all the way towards the operator.
Z is traversed all the way up.
This will result in X and Y moving from zero to increasing number position, and Z moving to a negative position as it goes down.
This convention will copy the normally most accepted arrangement of the XYZ origin.
And most importantly allow me to easily distinguish the numbering convention as I have been exposed to it over the years.
Now let's stop talking and get to setting up the machine!!!!!!
Thanks again.
Pat

[cncsnw]

If this is a knee mill, and you home the Y axis so the saddle moves toward the operator, then that is Y+: the tool is at the far side of the work envelope (off the back side of the table).

In machine coordinates (i.e. measured from machine home, which is machine zero) your working Y positions will all be negative. But you do not run CNC programs in machine coordinates, so that does not matter.

You will probably set your Part Zero (WCS) so that at Y zero, the tool is near the front of your stock to be cut. Your Y coordinates in your CNC program, then, can be positive.

[bgpv2xt]

'Yes it is a normal knee mill. The way I think about it is, looking down at the table the XY origin is 0,0 which will put the table traversed
1. All the way to the right to make X=0.
2. All the way closest to the base of the machine to make Y=0.
So when a X=10 and Y=10 movement is issued the table will move to the left 10 inches and 10 inches towards the operator.
I think that is the way it should be.
If not let me know, I did CAD for a while and getting the Y direction in my thought process on this machine is not as simple as it should be.
Thanks
Pat

[cncsnw]

It sounds like you are still confusing machine coordinates with local (part, WCS) coordinates.

[bgpv2xt]

OK so I sort of have it figured out ????? The thing that is confusing is there is no MACHINE HOME on the WCS list and I still don't know how to switch back to the MACHINE HOME position. I consider MACHINE HOME to be 0,0,0 which is the table all the way to the right and closest to the base of the machine and Z all the way up. Also there is confusion when I look at the display position numbers and the position of the table, or where I expect it to be??
Also today I have been messing with the Z height and tool offset heights, that is going to be another rocky learning curve ahead !!!!!
Thanks Pat