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Machine vs Program Coords questions
« on: February 10, 2010, 02:10:02 PM »
I know beginner questions are annoying so I appreciate your patience. In Turn I am unclear as to why on the manual screen there is a Program Coords. and a Work Coords. button. Smid's book on CNC Programming says that Program and Work Coordinates are the same thing.  There does not seem to be any explanation for this in the manual.

Also, is there anyway to tell when the Axis DRO is showing Machine Coordinates vs. Program Coordinates. You can tell this on the manual screen because the appropriate LED is lighted. However, on the Auto Prep and Auto Cycle screens it appears you cannot tell which mode you are in. I have found this confusing, but it could be I just don't know what I am doing.

I am wondering is there is any way to locate the 0 point of an axis in machine coordinates when the axis is not at that point, i.e. specifying zero without hitting the zero button. At one point when I was at z= 1 relative to where I want 0 to be I tried typing in 1 in the Axis DRO which I hoped would force  Mach3 to set 0 at a point -1 from where I was, but it would not take this. It is not a problem to jog the axis to right point, I am just curious if this can be done.

Thanks, Frank
 

Offline Hood

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Re: Machine vs Program Coords questions
« Reply #1 on: February 10, 2010, 02:17:14 PM »
Sounds like you were looking at machine coords, you can type into a DRO and it will change as long as you hit the enter key on the keyboard. If you are looking at machine coords however you will not notice the change.
Hood

Offline RICH

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Re: Machine vs Program Coords questions
« Reply #2 on: February 10, 2010, 02:32:22 PM »
Here is a link to Phil's screen set which i think you will find much better than the standard one.
It has Machine, Program, and Part buttons so you can easily switch between the three and see the  differences.
Very easy to get get confused.  ;)
Also has some nice features not in the standard lathe screen.

http://www.machsupport.com/forum/index.php/topic,13548.0.html

RICH
Re: Machine vs Program Coords questions
« Reply #3 on: February 10, 2010, 03:31:46 PM »
Hood,

Yes, in my item 3 of my request, I was trying to set the machine coordinates at a value different from zero. Are you confirming that you can only enter a value of zero?

Any comments on my question about how you know which coordinates the Axis DRO screen is displaying when in the Auto screens? Or the first one about what the Work Coords. button is for?

I appreciate you help. Frank

Offline RICH

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Re: Machine vs Program Coords questions
« Reply #4 on: February 10, 2010, 05:36:50 PM »
Frank,
You can know were X & Z  0 is if your lathe uses limit switchs or was homed using the soft limits.
Hope not to confuse, but one needs to read half the lathe manual to get a flavor of the different DRO's and what they are telling you. So i am going to try and help here, but will take it one step at a time. Can be rather hard to get grips on it all. You need to click each Machine / Program / Part button ,and a green light is on shown which is current, to see the changes in DRO.  Another thing, you need to know what each displays as can be different depending on the lathe mode your in ( diameter or radius ).

Machine coordinates just tell you where the controlled point is at any time based on a defined spot.
When you say ZERO button, i am assuming that you are refering to the Zero World X or Z buttons in the manual screen. Clicking those buttons will reset any offset( G54 offsets to zero )and now you are at Z &X =0 ( resets home to 0,0 ).Home can be anywhere.
That's my definition as i have never found a definition for it anywhere. Now i am going to repeat what i have already written, sorry,  go to the link below and read Homing a Lathe ( without limit switches ) as that will give you what you need to envision homing and machining coordinates.
Here is the link:

http://www.machsupport.com/forum/index.php/topic,11502.0.html

RICH
« Last Edit: February 10, 2010, 05:39:31 PM by RICH »

Offline Hood

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Re: Machine vs Program Coords questions
« Reply #5 on: February 10, 2010, 05:38:07 PM »
Frank
 You can only set the machine coordinates by doing a reference (homing) so no matter what you type into the Machine coords you can not change them. This is for good reason as machine coords are what Mach uses to keep track of things and normally a user will not look or care about machine coords,, note I said usually, there are times when you want machine coords but I will not complicate things at this time.
 What the user looks at and uses is offset coords, for example, you home the Z axis  so Mach knows where the zero position of the axis is in machine coords but you almost certainly dont want that as your Z axis zero position, you will want the end of the stock as zero. So what you do is move to where you want the zero to be and either hit the zero button for that axis or type into the DRO. You have now just set a Z work offset.

Afraid I do not like the Turn screen  and I have never used it so I am not familiar with the naming convention of its buttons, but I am sure others will let you know exactly what they do.

Hood

Offline RICH

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Re: Machine vs Program Coords questions
« Reply #6 on: February 10, 2010, 05:51:46 PM »
 COMMENT:
Machine coordinates read in absolute and the X axis dro will be based on radius values.
Program and Part coordinates read in absolute but will display X in diameter or radius and is mode dependant / depends on what you have set up in your config.

RICH

Hey Hood, please correct if i say something wrong...
Re: Machine vs Program Coords questions
« Reply #7 on: February 11, 2010, 12:18:02 AM »
Rich and Hood,

I really feel bad because I am making you waste time. I have read the manual, all three of them, extensively, repeatedly over the last month or so. I have avoided getting on the forum until I felt I was asking questions that I could not find the answers to in the manuals. (I am not saying the answers were not there, but that I either could not find them or could not understand them).

Almost everything you wrote in the last three posts I understand pretty well. In addition to your manuals I have read Briney on Machining, both Hayden and Hess on CNC Machining and Programming and I am a good way through Smid's Handbook on CNC Programming. I think I just am not good at expressing my question precisely.

I was referring to homing without homing switches. Your manual says, I believe, that you can enter data in all DRO's and hit Enter. So when I was trying to set up machine zero, I thought I should be able to do it relative to where the tool tip currently sits. So I tried and the system appeared to refuse to accept a value (which appeared to contradict what your manual says). So that is the reason for the question.

I think I understand offsets. I understand radius vs diameter. But what if you don't want to use an offset? What if you are running a simple program and you simply want machine zero to be program zero. I understand that that is not recommended practice, but I see no logical reason why you should not be able to do it.

I my specific issue I have little delrin rod that I am trying to turn and then cutoff. I want to do this repeatedly. Program zero is -.1" from the stock face so that I can face the piece before turning and cutting. I wanted to make machine zero - program zero and I wanted to do it without having to jog around the stock to y=0, I just wanted to leave it at x=0 and tell it where y=0 was (-.1 from the stock face).  This would make my repeated operation a lot faster.

So, I guess, from reading what you wrote the answer to the question is that no, you cannot set Home be defiining a location. You have to be at the location you are setting and the only value Mach3 will accept is zero.

If I haven't completely exhausted your patience I would still like to understand two other things: 1) what is a work coord. (from the Manual Screen)? Is the same as a program coord.? 2) when you are in the two Auto screens how can you tell if the Axis DRO is showing you macihine coords. or offset coords.?

Thanks. Frank
Re: Machine vs Program Coords questions
« Reply #8 on: February 11, 2010, 05:46:43 AM »
FALLen

I can understand your frustration but it makes no difference in the real world

If you didn't know about machine co ordinates and how to access them the program will work exactly as you want it too

I really must emphasize that you use a different screenset thanks to Klaus and his excellent MachScreen it is as easy as a word processor to alter the screens

But you've got to learn before you can walk there are loads to choose they are all free, some are just the same layout just different colours which is a shame

Phil
The Good Thing About Mach3, Is It's very Configurable

The Bad Thing About Mach3, Is It's Too Configurable

Offline RICH

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Re: Machine vs Program Coords questions
« Reply #9 on: February 11, 2010, 10:16:05 AM »
Ok, no switches, neither do i have any.
So you start LT Mach3Turn. Lets walk some.....because you are going to get confused later on if you don't know what is happening.
So we'll just practice a little and learn through experience.

If you press the Zero World X ( remember that gets rid of any offsets) in the manual screen then also press Set home X, Home=machine cordinates for the
x axis. No matter how you move along the x axis, Mach will keep track of were that controlled point is via machine coordinates.
Since machine cordinates are absolute and are displaying radius values you know the distance to X =0.  If you move the x axis to 0
and now Zero World X in the manual screen then also press Set home X, Home=machine cordinates for the x axis which is
equal to 0.

Home can be anywhere you want.

Now do this,  do the same for the Z axis such that when you are done you will have set the machine coordinates and
 home  to Z=0 such that it is at the end of the stock.

After you have that done, move the Z  axis some distance. Now press the Program and machine coordinate buttons making note
of  the dro's for each. What are they telling you?

 If you press the Home Z, the axis will move back to home.

RICH
« Last Edit: February 11, 2010, 02:02:00 PM by RICH »