Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: davelegg on June 06, 2016, 11:50:58 AM

Title: Table size
Post by: davelegg on June 06, 2016, 11:50:58 AM
I am having a beast of a time setting my table size and getting my machine coordinates to do anything. I can get the dros to zero in the work coordinates but not in the machine coordinates.
Am I right in that the machine coordinates button is showing the machine coordinates when the red led is lit around the button?
Below is my homing/limits settings.

Title: Re: Table size
Post by: ger21 on June 06, 2016, 12:40:50 PM
You have to home (ref) the machine to zero the machine coordinates.
If you don't have home switches, then the machine coordinates will be zeroed at the current location when you click the Ref All button.
Title: Re: Table size
Post by: davelegg on June 06, 2016, 03:54:28 PM
I have limit switches on all axis. will that work?
Title: Re: Table size
Post by: ger21 on June 06, 2016, 04:01:59 PM
If you configure them as home switches, yes.
Title: Re: Table size
Post by: davelegg on June 06, 2016, 04:10:52 PM
Please elaborate. New to all this
Title: Re: Table size
Post by: joeaverage on June 08, 2016, 03:52:06 AM
Hi Daveleg,
on the 'input pins' configuration screen you can assign a port and pin number to Xhome, Yhome, Zhome, etc.
Clearly the pin you assign must be input capable.
On the 'homing limits' configuration screen you can assign things like the direction to approach a home switch
and the speed as a percentage of traverse speed to approach at.
A home switch is usually a microswitch or some equivalent and can be anywhere on an axis but it is common
practice to put it at one end, aka a limit switch. When you hit the RefAxis button the machine will drive in the
preconfigured direction and speed until the switch operates, stop and back off a small distance and 'zero' the
machine coordinate for that axis. The machine will maintain the machine coordinate for that axis for the remainder
of your machining session or until you repeat the 'referencing' because of an axis stall or worse a crash during the
Note also that on the 'home/limits' page you can assign your soft limits which define the safe operating area of your
machine and is seen in the toolpath display as table limits.
You can use the home switch as a limit switch by disabling the limit function (usually an Estop and/or drive power
disconnect) while homing and the re-enable the limit for the remainder of the session.
For the purposes of a home switch a device which can repeatably trigger at a precise location is required. Inductive
proximity switches can be a bit vauge for this purpose. I use top quality roller plunger microswitches, Omron is
the manufacturer but indentical units are made by others, Allen Bradley certainly and if memory serves Honeywell as well.
Look at the specification for the switching limits usually mentioned 0.02mm /0.05mm or similar, the price also gives them
For limit switches less precise units suffice including proximity switches. I prefer seperate limit and home switches, I find it
reduces confusion and have had less 'operator induced crashes' since I adopted the idea. All the limits (x++,X--,Y++,Y--,Z++ and Z--)
are in series and if any one operates then my machine is in trouble and Estops immeadiately, no exceptions. The home switches
trigger about 2mm short of the limit and so homing never operates the limits unless there is a fault in the home switch wiring/components/