hello
Is there a way to set up mach3
When I click 'ref all home'
I would like to move the z axis upwards to its limit, then reference the x and y axis, then finally move the z axis  down to reference it.

Is there a way to do this?

Thanks

By definition Ref All Home moves to the reference switches.  Why don't you just use your z limit as z home?  Why do you particularly want to reference the z axis?  I never use ref all home, I just pick up the x y and z coords of the workpiece.  But that's on a mill - are you referring to a plasma machine?

Hi,
yes there is, look on the Homing/Limits page.

Referencing requires home switches. For instance if you have a switch on the X axis, it doesn't really matter where, just somewhere on the axis, when the carriage activates the switch Mach can
say 'I know where I am on the X axis', or as we say, 'referenced'. Thereafter Mach can keep track of where it is but it needs some definite point to start from.

Its common to put  home switches at or near the end of the axis, its not required but it is common. Its also possible to use a limit switch as a home switch. In the early days of Mach when everyone had a
parallel port with only five inputs is was common to have limit switches double as home switches. Today with external controllers with lots of inputs we don't have to do that anymore but lots do.
I personally think it causes a lot of confusion all to save an input or save mounting another switch.

What happens is that when you hit 'Ref All Home' Mach ignores the limit switches and treats them as home switches. Once the machine is homed then it turns the limits back on and turns the homes
off. It means that while your machine is homing, just when you need it, you don't have any limit switch protection. I think that's dumb. Anyway that's exactly what a lot of people do. If you chose to do
the same and crash your machine just remember you chose to do it this way.

Set the 'Home Order' so the Z axis moves first, ie 1. When it goes to the top limit it will call that home and will set machine coordinate DRO to zero, or whatever number you set as home offset.
I would recommend not to worry about Home Offsets to start with, just have the machine coordinate go to zero. The next axis in the 'Home Order' will now drive to its limit, or because Mach is ignoring limit
switches, its actually a home switch at the moment. When it gets there it will set the machine coordinate for that axis to zero. The last axis will do the same thing.

Once all three axes have 'homed' the contolled point (usually the spindle) is at machine coordinates 0,0,0. Now you can shift anywhere, usually to the corner of the workpeice and 'zero the axes'.
Zeroing in this instance means the work coordinates, not the machine coordinates.

Craig

Hi,
John is right you don't have to reference your machine however if you do it means that soft limits now work as intended.

Like John I did not bother referencing my machine and operated like that for nearly a year. Then I got around to fitting home switches,  just three home switches, not limits....and have never looked back.
Fitting good quality home switches and therefore having useful softlimits has reduced the number of crashes from a few every so often to once in last four years, and that one time was when I got
confused and did not home my machine prior to starting some code.

I use roller plunger microswitches and get 0.02mm repeatability. It means I can stop a job part way through, turn the machine off and come back tomorrow, reference the machine and take up from
within 0.02mm from where I left off yesterday, real REAL handy.

I highly recommend good home switches and preference is that they be dedicated for just that one job, ie homing. Leave limit switches to be just that...limit switches alone.

Craig

Yes it is a plasma table.

I tend to just click ref all home for ease and let it do that (Table is 3 metres by 2 metres) while i sort other things out.

I have only just realised from what you both have said that I can reference z to the top and enter the measurement in the homing page.

Hi,
yes that's correct, it doesn't really matter where the Z axis is referenced, at the top or somewhere else. You seldom look at the machine coordinates, Mach does that and keeps track of them.
You and I are more interested in how far we are from the corner of the workpeice, work coordinates as opposed to machine coordinates.

Craig

On a plasma the Z is rarely referenced at all, usually they have floating heads and will detect the top-of-material every pierce or two, thats all that matters to a Z on plasma.

if you have Limit Switches for all axis, it should be no Problem.
maybe a Little Change in the ref all button script.

+ a Floating head connected to the probe Input for detection of material surface,
then you can "cover" all

Thanks

Yes I have limits on all axis.

I have looked at it a bit today.

Here is what I think I want to happen.

I click ref all home

Z axis moves upwards clear of any thing on the bed, say for instance my cup of tea, say 150mm.

Now it zero's Y then X axis

Then Z moves downwards landing touch probe on small platform in the corner.

No tea spilt

ok Sounds good so far.
first would be to get the referencing working of the single axis.
means:

press Ref Z make sure the referencing Z is working, upwards to your Limit switch
press Ref X make sure the referencing X is working
press Ref Y make sure the referencing Y is working

if we have this working, we will create a customized ref all home script