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Zeroing machine coordinates
« on: August 22, 2010, 06:14:05 PM »
Hi,
I am quite new to all of this CNC-stuff, but I have successfully got my milling machine up and running and have run my very first program.

But, I have trouble with changing tools within the same program. I change tools manually, and I don't have any home-switches or means of detecting tool length.
So, the way I run a program now is:
Mount tool #1
Jog down until tool-tip touches table
Zero Z machine-coordinate
Jog to corner of work piece with tool-tip touching the top, which is my (0,0,0) in the CAM-program (and (0,0,0) in G54 fixture)
Run until next tool change
Mount tool #2
Jog down until tool-tip touches table
Zero Z machine-coordinate
Run rest of program

I plan to semi-automate the Z-zeroing using a switch later.

Anyway, all this works just fine. The problem is that I can not just press the ZeroZ-button to zero that coordinate (nothing happens). I must use the "REF ALL HOME", with auto-zero enabled only for Z. As I have no home-switches, the only effect is that Z is zeroed. This also means that to actually home the machine, I'll have to turn of the drivers, move to home, enable auto-zero for all axis, "REF ALL HOME" and turn on the drivers. Then I have to disable auto-zero for X and Y before doing the program run procedure above.
Sure, it's not very hard to do, but it would be much better if I could just click the ZeroZ-button and have it zero that machine coordinate (and not affecting the work piece coordinate system G54).

Is there a better way, or can I enable the ZeroZ-button, or could I perhaps do this with a script of some sort?

Regards
Alex

Offline ger21

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Re: Zeroing machine coordinates
« Reply #1 on: August 22, 2010, 06:24:09 PM »
Quote
Zero Z machine-coordinate

How are you doing this?

And why do you need to unplug the drives to Ref All Home? Without switches, the machine won't move.

I can zero my Z in G54 anytime, even as soon as I start mach3?

You should be able to just turn on the machine, click ref all home, then just set you G54 zero and work from there. When you change tools, just zero Z in G54. Not sure why your Z zero button isn't working??
Gerry

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Offline Hood

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Re: Zeroing machine coordinates
« Reply #2 on: August 22, 2010, 06:27:27 PM »
Machine coords are how Mach keeps track of where it is.
The easiest way I can see for you is  to touch off your work with the first tool and zero the Z DRO, then jog to the side and touch off the table and take a note of the number. When you come to use the next tool just jog to the table then enter the value you previously noted into the DRO and you should be all set.
Hood

Offline BR549

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Re: Zeroing machine coordinates
« Reply #3 on: August 22, 2010, 07:10:56 PM »
You should be working in user coordinates not machine coordinates. Sounds like you are in machine coordinates if the zero axis button does not work.

Just a thought,(;-)
Re: Zeroing machine coordinates
« Reply #4 on: August 22, 2010, 07:26:10 PM »
BR549: I am working in user coordinates, but I want to reference tool-tip touching table as machine Z=0

Let me explain better.
The G54 is no problem to zero or set to any value at any time. But, as I don't have home switches and still want the machine-coordinates to be accurate, I have to zero the machine manually. I do this by moving it to zero with the drivers turned off and then pressing ref all home (with auto-zero on x and y) to get the machine coordinates to zero. Now when I turn the driver on real position of the machine is the same as the machine coordinates.

Hood:
Yes, that is almost how I do it now. I would also touch off the second tool on the work-piece, but it's not always possible as the whole surface might be machined by a previous tool. Therefore, I use machine coordinate Z=0 when the tool-tip touches table.


Actually I think I found a solution by my self. SetMachZero(2) script-command seems be the equivalent off ZeroZ (for machine coordinate). Maybe mapping it to the Auto Tool Zero would make good use of that button.

Offline Hood

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Re: Zeroing machine coordinates
« Reply #5 on: August 22, 2010, 07:34:03 PM »
Yes SetMachZero(2) will indeed do it, so will DoButton(24)

Still not clear why you are doing things the way you are but if it works for you then I suppose thats what counts :)
Hood
Re: Zeroing machine coordinates
« Reply #6 on: August 22, 2010, 07:39:16 PM »
This way I don't have to enter any coordinates at all. I just have to jog the tool to table and press a button. Unless I have a Z-level which is not machine with a previous tool, then I can off course just zero the user coordinate touching off on the work-piece.

Offline Hood

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Re: Zeroing machine coordinates
« Reply #7 on: August 22, 2010, 07:42:00 PM »
Major drawback I see is you will not be able to use Soft Limits.
Hood
Re: Zeroing machine coordinates
« Reply #8 on: August 22, 2010, 07:44:16 PM »
Well, semi-true. The limit for max-Z will not be accurate, but the low-Z will make sure I don't slam the tool into the table. X and Y still works fine.

Offline Hood

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Re: Zeroing machine coordinates
« Reply #9 on: August 22, 2010, 07:47:05 PM »
each to their own I suppose :)
Hood