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Machine Coord's
« on: October 13, 2016, 12:40:13 PM »
Can you zero the values in the readout for the coord's I tried using the zero buttons and nothing happens.

Offline Davek0974

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Re: Machine Coord's
« Reply #1 on: October 13, 2016, 01:30:29 PM »
Only way to zero the machine DRO's is to home the machine :)
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline rcaffin

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Re: Machine Coord's
« Reply #2 on: October 15, 2016, 04:51:19 AM »
What Dave said, BUT ...
If you do not have Home switches on the machine, or at least do not have assignments for Home switches in the Pins&Ports page, then you can fake the Home op. Go to where you want the nominal Home to be and click on 'Ref All Home'.
If you then zero all DROs you will have both Machine Coords and User Coords with the same origin.

Cheers
Re: Machine Coord's
« Reply #3 on: October 15, 2016, 06:12:48 AM »
Hi,
as rcaffin says if you don't have home switches assigned then when you 'ref' either an individual axis,
say refX or all of them at once refAll the machine cords zero. It is sometimes called 'zero in place'.

While quite useful when experimenting on a computer it is problematic if not downright dangerous on
a working machine. I know, I tried it in the early days and had a few crashes as a result, the last one
nearly crushed my hand!

If you assign home switches on the 'inputs' page of 'ports and pins' then Mach3 will on calling a 'ref' operation
drive in a direction and speed you set until the requested home switch operates whereon it will stop, back up
a wee bit and zero the machine coord.

My standard procedure when starting my mill is to first manually flick each of the home switches while observing
the diagnostics page to confirm that Mach 'sees' each switch, ie a wire hasn't fallen off or coolant leaked into the
switch or similar. Then hit 'ref all'. The Z axis drives upwards until it triggers the home switch a few mm short of
the end of travel, it stops a zeros the machine coordZ. Then does similar to Y then X axes.

As Dave has said with home switches assigned then the only way to zero machine cords is to call a 'ref' operation,
ie 'zero in place' no longer works.

Thereafter you can MDI to the location of your work piece and 'zero' the DROs. The diagnostics page will show
the machine cords of the current position and the work offsets such that the DROs read zero.

If you have home switches then you can set 'soft limits' on the homing/limits page and then maximum extent of
travel will show in the toolpath screen which allows you to ensure that the Gcode of the job you are running does
not exceed the boundaries of your machine. If you don't want to break stuff or hurt yourself its mandatory.

As I said above you can use Mach without home switches and zero in place. The problem is when machining
thru multiple setups you WILL make a mistake when shifting work origins and crash your machine. My mill uses
planetary reduction on the steppers and despite being only 23 size they generate over 1500lb of thrust, when
it crashes bad things happen. Don't be caught!

Craig
My wife left with my best friend...
     and I miss him!

Offline rcaffin

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Re: Machine Coord's
« Reply #4 on: October 15, 2016, 03:52:02 PM »
While quite useful when experimenting on a computer it is problematic if not downright dangerous on
a working machine. I know, I tried it in the early days and had a few crashes as a result, the last one
nearly crushed my hand!


I will gently disagree here. In many years of CNC I have never found any dangers with the lack of Home switches. True, my programs always request confirmation that the zeroes have all been set up. But that is simply 'good practice'.

As for nearly crushing a hand - just don't have your hands inside the working envelope when the machine is running. And don't leave any loose tools or bits inside either. It's a machine, and 'A machine does not care'. Many machines have guards or covers for that.

Cheers
Roger

Offline RICH

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Re: Machine Coord's
« Reply #5 on: October 16, 2016, 08:00:45 AM »
I haven't used home switches on any of my machines for years. Never had a problem.

One needs to decide on the level of automation they desire or need. Consider the following or combinations of the following
for the controller:

1. Manually define home and part location.
2. No switches but will define in a soft way where home is
3. Use switches to auto home the machine
4. Use switches to home and auto probe to find the part
5. Continue automating using devices and routines to automate the process of
   setting up the work to be done.

Quote
Can you zero the values in the readout for the coord's I tried using the zero buttons and nothing happens.

Now back to that original question ...........
This tells me there is lack of understanding of basics. It's of not much value to just say push some button or whatever
and not know how it will affect things.

RICH

Offline RICH

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Re: Machine Coord's
« Reply #6 on: October 16, 2016, 08:57:37 AM »
Some basics................


The CNC Controller is a software Program called Mach 3 and provides for controlling all the movements and associated commands. The CNC controller (Mach) does not know a "practical" Machine Reference Point to work from, thus, the controllers “0,0,0” is somewhat meaningless and has unlimited movement capability.  When the controller is turned on it monitors axis movement starting from Mach's  “0,0,0” value for each axis and displays the absolute movement using Machine Coordinates.


Machine Zero is a fixed point within the physical machine travel limits and does not normally change. It is typically called Machine Reference point, machine zero, or simply Home Position.  Machine zero can be located / defined anywhere by the user. Usualy it is located to provide for full available machine travel usage.

Part Coordinates are distances from a fixed point( machine zero as defined above ).
The controller needs to know where the part is relative to machine coordinates. The part zero can be located anywhere. The part has coordinates associated with it and normally the same location of the part is the basis for xyz= 0 in a gcode program. The software can’t properly control the machining of the part if it doesn’t know where the part is. Part coordinates can be equal to or even the same as Machine Coordinates. Thus defining the part location is very dependant on how a user sets up a job including how the gcode program was created.  So part coordinates are used to relate or define where the part is relative to the machine coordinates.

In general, only the user can define where the part is located to the controller.

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A way to see how the controller keeps track of location /reacts to different button use is to go to the Diagnostics Screen and try different button's and watch the DRO's on the screen. Also change values in the DRO's and see the affect.
- Ref All Home
- Zero All, Ref axis button
- De Ref All Axes ( the button is on the MDI Screen )
- jog a defined step say 0.1"
KISS....only do a small move and one axis only

BTW,
The lathe has some different buttons.
Note that level of configured automation has an affect on intial state of the machine on
start-up.

FWIW,

RICH
« Last Edit: October 16, 2016, 08:59:24 AM by RICH »