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Absolute Machine Coordinates Shifting??
« on: March 09, 2015, 01:43:44 PM »
Hello,

I'm new to Mach3 so forgive me if I do not use the correct jargon. But here is my issue:

I've set the work coordinates G54 as (let's say) X=1, Y=1, Z=1 in absolute.
Now from what I'v figured out, each time I open Mach3 it will use G54 as a default work coordinate system.
So G54's zero should be at Machine Absolute's X=1, Y=1, Z=1.

But each time I close and open, G54's zero is now at something like Machine Absolute X=.5, Y=.5, Z=1.

Why might this shift be occuring? How does Mach3 come up with the Machine's Absolute Coordinate's upon boot up? Am I wrong to have expected it to be the same each time?

Thank you,

Corey

Offline Hood

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Re: Absolute Machine Coordinates Shifting??
« Reply #1 on: March 09, 2015, 02:30:58 PM »
I presume you do not have home switches from the way you are describing things.
There are options in General Config for such things as persistent offsets and DROs, maybe some of them are wrong.
If you are using an external controller then it might be it that is setting the DROs to something on start up.
Hood
Re: Absolute Machine Coordinates Shifting??
« Reply #2 on: March 09, 2015, 03:44:41 PM »
You presume correctly. Maybe switches will ultimately be the best way to go. But for now I'll need to play with the software to figure out a solution.

And yes, both my persistent Offset and DRO are checked. As well as the "save offset" box. (Not that I know entirely what having them checked means haha)
But I assume that is why it asks to save my fixtures upon closing the program?

By external controller what do you mean? Doesn't Mach3 need to be installed on a external controller (i.e. a computer). I'm running it on Windows 7. Is that considered an external controller? And what else can Mach3 be installed on besides a computer?

Does anyone know how it sets the DRO's at startup? If I can figure that out I might be able to control it somehow.

Thanks!

Also, one side question: Does Mach3 support conditional statments? (e.g. If-Then statements with AND/OR logic devices)

Offline RICH

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Re: Absolute Machine Coordinates Shifting??
« Reply #3 on: March 09, 2015, 03:56:59 PM »
Suggest you post your xml file.

How does Mach3 come up with the Machine's Absolute Coordinate's upon boot up?
Go to Diagnostics after Mach opens. The table at the top of the screen shows how the current position is calculated.
Mach defaults to G54 offset on startup. Also note the current Mill> items in affect.

Depending on some settings and  configuration, what you did after start up, the state of things on exit can all affect what
happens when Mach is opened. I will add that Machine Coordinate 0,0,0 is used at start up from a controlling software viewpoint as it dosen't know a practical machine reference point 0,0,0 (ie; home position / referenced) until it is defined by you in sme manner to the controller.

May want to start reading the manual,

RICH

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Re: Absolute Machine Coordinates Shifting??
« Reply #4 on: March 09, 2015, 04:11:29 PM »
Yep you need to read the manual.......

Do this to get a flavor since you don't have switches:

- Open Mach,
- Click each Zero button next to the axis
-In the MDI separately type the following:
G54 X0 Y0 Z0
G92.1
-Exit and reopen Mach.

RICH

Offline Hood

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Re: Absolute Machine Coordinates Shifting??
« Reply #5 on: March 10, 2015, 06:33:30 PM »
The parallel port is the native controller for Mach, it uses the computer to do the pulsing for the Step signals. There are lots of external controllers that work with Mach, they do the pulsing in hardware which makes much cleaner pulses and are usually capable of a much higher pulse rate than the parallel port. There are also other external controllers that can output +/- 10v command instead of Step/Dir, these are used to interface Mach with servo drives/amplifiers that tend to be used in industrial CNC machines.

Hood