Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Ebygum on October 31, 2017, 04:32:01 AM

Title: Work coordinates
Post by: Ebygum on October 31, 2017, 04:32:01 AM
Gday,
After setting up my limits and all working fine.
I setup G59 as per coordinates but when I tried to send the machine to these coordinates the X & Y worked perfect but the Z didn't move.
If I had any hair it would be in jeopardy.
Any assistance would be much appreciated.

cheers

Trevor
Title: Re: Work coordinates
Post by: joeaverage on October 31, 2017, 04:39:22 AM
Hi Trevor,
you say that you've set up your limit switches and they are working. What about home switches? How do you reference your machine?

Soft limits, work co-ordinates are just so much hot air UNTIL the machine is referenced.

What sort of controller are you using?....parallel port or USB external controller?

Craig
Title: Re: Work coordinates
Post by: Ebygum on October 31, 2017, 05:02:56 AM
Gday Craig,
The limits I referred to are the Home Limits (proxies).
To reference the machine I hit the ref all button.
The machine then goes to the 0,0,0 which I presume is correct.
Its only when I go to the work coordinates that the problem rears its head

cheers

Trevor
Title: Re: Work coordinates
Post by: joeaverage on October 31, 2017, 05:22:27 AM
Hi,
so are they limit switches (at the ends of the axes) or home switches or do they do double duty and do both?

When you hit <ref all> does the machine drive to some location?

What sort of controller are you using? There is a reason I'm asking...its because I want to know if its going to be feasible to get you to fit three dedicated
home switches each with its own input. This may strike you as over the top...its not. It reduces confusion and because you use decent microswitches
way more accurate and repeatable.

When you say that all axis DROs are reading zero now go to the diagnostics page. Each axis has a current position which is calculated from the machine
position and the prevailing work co-ord for that axis. Note you cannot change the machine co-ordinates EXCEPT by shifting the axes by jogging, MDIing
or running Gcode OR referencing (homing). Mach is quite happy and extremely good at maintaining a true and correct set of machine coordinates BUT it
needs to know where to start to keep its record, hence the home switches. It common to have the switches at or near the end of each axis but it doesn't have to be.
My home switches are set up to trigger about 10mm short of the end of the axis (where the limit switches are). The important point is that everytime you turn
Mach on that you reference to the exact same place, or as near exact as you can then softlimits make sense and so do work co-ordinates saved from a previous
session.

Craig
Title: Re: Work coordinates
Post by: Ebygum on October 31, 2017, 05:54:04 AM
Gday Craig,
The proxies are home switches.
I home the machine by hitting Ref All.
I then use my handheld controller to jog to a work and setup the XYZ coordinates.
Then to the Offset screen and Click the XYZ buttons on the Machine Coordinates which transfer them over to the works coordinates and them I save.
I then go back to the first screen and hit the ref all to zero the machine and hit Go to Zero to check my works coordinates are working.
Previously the X&Y worked but the Z did not.
Just been down and checked it again and all seems to be working.
Bloody Gremlins.

cheers

Trevor
Title: Re: Work coordinates
Post by: joeaverage on October 31, 2017, 01:21:01 PM
Hi,

Quote
I home the machine by hitting Ref All.
Does the machine drive to its Home location?

Quote
I then use my handheld controller to jog to a work and setup the XYZ coordinates.
So you manually jog to the desired location.
Do you hit <zero X>, <zero Y>, <zero Z>? If you do it forces the work offsets to be such that the current position co-ords are zero, ergo the offsets
will be equal and opposite the machine co-ords. You don't need to transfer anything.

The machine co-ords are important to your machine and Mach will track them but you don't need to see them. You reference once. Manually jog to where
you want to  call 0,0,0 in your work cords for this session and hit <zero x>,<zero y>,<zero z>. You can now run your program. Each and every time you
hit the <zero> buttons the local 0,0,0 changes, so if you put a new piece in your vice jog to the corner, touch the tool on the surface, hit <zero> buttons
and the machine is ready to run the code.

Do you have separate limit switches? How are they wired?
What type of controller are you using?

Craig
Title: Re: Work coordinates
Post by: Ebygum on October 31, 2017, 08:58:31 PM
Craig,
Yes I have seperate proxies and I am running Mach 3 on a converted Chinese machine.

Trevor
Title: Re: Work coordinates
Post by: joeaverage on October 31, 2017, 10:02:54 PM
Hi,
so does the machine drive of its own accord to the home location?

When the Ref All is complete and the machine co-ordinates are zeroed does the border of the <zero (axis)> go green?

Craig
Title: Re: Work coordinates
Post by: Ebygum on November 01, 2017, 09:54:02 PM
Gday Craig,
Yes the borders of the zero axis goes green when I REF ALL HOME and the DRO display zero.
I thought everything was OK but its not.
I have noticed that when I travel the Z axis down from home position the DRO has a + value and I was under the impression it was suppose to have a - value.

Trevor
Title: Re: Work coordinates
Post by: joeaverage on November 01, 2017, 10:27:13 PM
Hi,
it is common for the Z axis machine zero to be at the top of its travel. If you were observing
machine co-ords then any Z co-ordinate within the machining volume would be negative.

It is unusual to have the machine co-ords displayed in the DROs, it is the norm to have work co-ordinates
displayed where zero is the surface of the material, positive Z above the material (safe) and negative Z
means below the surface, that is machining and producing chips if all is well, or a crash if you haven't got it
right.

If you look on the diagnostics page you will see how the current position is calculated from the machine co-ords and the
current work offsets.

There is a button that causes the machine co-ords to be displayed in the DROs, hitting the button and the DROs go back
to the current position which is the 'normal' condition.

The green border around the <zero (axis)> button means that axis is referenced.

Craig
Title: Re: Work coordinates
Post by: Ebygum on November 01, 2017, 11:18:40 PM
Gday Craig,
Would like to send you some screen shots and see if you can pick out what I have wrong but cant figure out how to send them in this forum

Trevor
Title: Re: Work coordinates
Post by: joeaverage on November 01, 2017, 11:33:23 PM
Hi,
take the screen shots.

post to this thread but go to <Additional Options> to the left of the text window browse to your screen pics
folder and attach the files. You can attach up to four files per post but try and keep the individual files a modest
size, less than 300kB if poss.

Craig
Title: Re: Work coordinates
Post by: Ebygum on November 01, 2017, 11:48:20 PM
Gday Craig,
Don't seem to have the Additional Options facility.
Can I email you?
Sorry for being a pain.

Trevor
Title: Re: Work coordinates
Post by: joeaverage on November 02, 2017, 02:09:24 AM
Hi,
<Additional Options> is on the same page as you create the text for a post.

 Email is fine but that means I see it and no one else does, I don't need the help...others do and so I wish you to post it so they can benefit too.

Craig
Title: Re: Work coordinates
Post by: Ebygum on November 02, 2017, 03:43:35 AM
Gday Craig
Just testing
Title: Re: Work coordinates
Post by: Ebygum on November 02, 2017, 03:47:18 AM
Gday Craig,
Seems to be working
Title: Re: Work coordinates
Post by: Ebygum on November 02, 2017, 03:50:53 AM
Me AGAIN
Title: Re: Work coordinates
Post by: Ebygum on November 02, 2017, 04:01:13 AM
Gday Craig.
I am trying to produce a lithophane on a plastic pipe so if you think the cutting file would help I will post it.

Trevor
Title: Re: Work coordinates
Post by: joeaverage on November 02, 2017, 04:42:45 AM
Hi,
good work with the posting.

I see that you have referenced (homed) the machine, that is good. So what exactly is the problem?

I see for instance that the current work offsets are being applied but they may no longer be relevant to the job on the table at the moment or may be
left over from your last session.

Lets imagine that you've just turned Mach on, referenced and now you want to load a piece of material and cut it. When you place the material in the vice
it will almost certainly not align with the previous work offsets from the last job.

What you do is manually jog to the corner of the material (or wherever on the material that the Gcode 0,0,0 is drafted for) and hit <zero X> and <zero Y>.
Now manually and carefully jog downwards until the tool just touches the surface of the material and hit <zero Z>. The work co-ords of the point are 0,0,0.
The machine co-ords will be different, in fact they will be negative of the difference between the machine zero (your reference or home point) and the
'beginning' point of your Gcode job. Mach cares about machine co-ords but you don't. If you want to see them that's fine but I find they're a source of confusion.

The real value of referencing your machine is now Soft Limits (on Config/Homing-Limits page) make sense. You can have them drawn on the toolpath
display (Config/Toolpath.....check <Machine Boundaries>) and see whether your Gcode job is within the boundaries. If not  shift the material so that you
think it is within bounds, jog to the new 0,0,0 point as before, hit <zero X>,<zero Y> and <zero Z> and <Regen Toolpath> and you can now confirm that you
shifted the material enough and in the right direction to bring it within bounds.

This is a very simple procedure, no need to do any calculations or manually enter numbers into DROs just jog to the 'origin' of your part and zero your axes.
What actually happens is the work offsets get updated to negative the difference between your new intended work 0,0,0 and the machine zero (home point).
Easy really...but it takes a little practice before the simplicity and elegance of it become plain.

Craig
Title: Re: Work coordinates
Post by: Ebygum on November 02, 2017, 05:34:30 AM
Gday Craig,
The problem is when I set my work coordinates and run a cutting file the Z axis does not move to where I set it . X&Y work fine.
Plus I noticed when cutting a flat file (not rotary)it doesn't cut the same orientation as it looks on Vectrics .
Thanks for your patience.

Trevor
Title: Re: Work coordinates
Post by: joeaverage on November 02, 2017, 05:44:27 AM
Hi,

Quote
the Z axis does not move to where I set it
How are you setting it? Just typing in a number may change the DRO but it wont shift an axis. You must
jog or MDI or execute Gcode to shift an axis.

Quote
Plus I noticed when cutting a flat file (not rotary)it doesn't cut the same orientation as it looks on Vectrics
Then one of your axes is in the wrong direction relative to your CAM program.
Title: Re: Work coordinates
Post by: Ebygum on November 02, 2017, 05:57:07 AM
Gday again,
I set the Z axis the same way I set the X & Y.
I use my handheld and jog it to the correct position and in OFFSETS click the X Y Z which transfers the setting over to Work Coordinates but when I try to run a cutting file the Z axis does not move to the set position.

cheers
Trevor
Title: Re: Work coordinates
Post by: joeaverage on November 02, 2017, 06:02:19 AM
Hi,
just writing numbers into a DRO or a work offset  does not cause an axis to move.

Quote
I try to run a cutting file the Z axis does not move to the set position.
This won't happen... the Z axis will not magically move it has to be jogged or MDIed or under Gcode control.

Craig
Title: Re: Work coordinates
Post by: Ebygum on November 02, 2017, 06:10:21 AM
Gday Craig,
Do you have a 4th axis?
If so I will download my cutting file so you can give it a go.

Trevor
Title: Re: Work coordinates
Post by: joeaverage on November 02, 2017, 06:14:06 AM
Hi,
no 4th axis.

Craig
Title: Re: Work coordinates
Post by: Ebygum on November 02, 2017, 06:15:55 AM
Anyway thanks for your help.

cheers

Trevor