Just "Ref Z Home" available? (vs ref all home)

[HankMcSpank]

Hi there,

Up until now, I've been using "Ref all home" button to take all axises (axii?) to their respective homing switches - however, is there a command (or button) that I can use where only the Z axis homes to its switch? (for say a tool change)

Also, Is there anything command that could say be integrated into my GCode that would do this each time a tool change is required? (because it's kinda getting old shuttling up the Z axis each time I need to swap out tools!)

[multiplex]

curious about this too!

figured one way would be to add in a button just to execute the z axis (or whatever axis).

[HankMcSpank]

Some googling suggests for the latter part of my question that Gcode command G28 will do what I want.

I found this link...

http://www.mail-archive.com/emc-user.../msg07873.html

Extract here...

"a G28Z0 with no space will home the Z axis only"

So I guess if I edit my Gcode to have that immediately before a Tool change, that'd work.

It'd be nice to have a button in Mach 3 though - is there one? Could one be done via a screen editor (ie is it possible to submit Gcode via a nominated Mach3 button?)

[ger21]

Make a new button, and set it for VB script, and use the code DoButton(24).
Or, save it as a macro, say M500.m1s (I think it's m1s, don't have Mach installed here). Then you can just call M500 to home the Z axis.

[Torchhead]

One of the nice options in the CAM package SheetCAm is there is a Tool Change option that lets you automatically drop in several lines of G-code anytime you change tool numbers in the process list. So you can do something like this:

M05 (turn off spindle)
G00 Z 2.500 (raise Z up 2.5 inches)
G00 X8 Y8 (rapid to tool change location)
M00 (pause until Cycle start [RUN] is hit)

You don't have to move up to a Home so the calibration of the machine stays the same.
If you need to rezero the tool end on the top of material then just jog it down and hit Z zero button.

The option sticks the correct g-code in the right spots so you don't have to edit code.

You could put the same thing in a macro named M100 or higher and call it in the code.

You can also drop in a Z ref command in the same code snip
G28.1 Z .500 (rapid up to .5 then move at homing speed to Z home switch)
but I'm not sure what advantage that gives you since a home up in the air has no relation to the end of a tool or where the top of the material (Z 0) is.

TOM caudle
www.CandCNC.com
Totally Modular CNC Electronics

[HankMcSpank]

Thanks guys...I've read you replies a few times & while I understand the concepts, having just implemented a Z homing switch, this Z plane usage during a tool change is doing my head in!

I now think I've asked for the wrong thing - in the end I managed to program a spare switch on my contour shuttle, to home the Z Plane...but now I realise that's not going the help me!

Here's what I'm trying to achieve (my mill does not have a gantry)

Start Mach3
Hit "ref all home".
Load up Gcode file.
Clamp material to table
Got to Z (place centre of the table under tool)
Fine adjust axis to line up precise location of "working" 0,0 - zero X & Y.
Touch off top of material - zero Z.
Start Cycle off...........code is stepped through until a tool change is triggered

Now this is where it get fuzzy.

I intend putting plastic depth rings on all my cutters - each one being located the same preset distance from the tool tip ...the theory being, this would allow to locate Z0 just the once (when the first tool is loaded), then after every tool change it no more touching off would be necessary.

I need to try & figure this out...I know you've given me some leads, but being a relative new hobbyist, I'm still grappling with the concepts!

I guess all I need is what you've said - a simple macro, that when a tool change is triggered ..Mach3 raises the Z Axis about 50mm - can Mach 3 do this?

(I don't have spindle on/off control, so there'd be almost nothing in the Macro).

how to call a macro by Mach3 - specifically when a tool change is triggered?
Does it have to be a special name & directory location?
could anyone give me a lead what the Macro should contain (remember all I want is the Z plane to raise by 50mm - nothing else!)


Many thanks.

[ger21]

M6 is the tool change macro. There are actually two macros. M6 start and M6 end. You probably want to modify the M6end.m1s file to move to your tool change position. It already has code to remember where it is and to return there after the change.

[HankMcSpank]

I've found those two Macros, trouble is, it's not clear what I need to add in to get the Z azis to raise 50mm at tool change & then drop 50mm again to proceed with the cycle...

Here's the (default) contents of those macros...

M6Start.m1s
tool = GetSelectedTool()
SetCurrentTool( tool )

M6End.m1s.....
x = GetToolChangeStart( 0 )
y = GetToolChangeStart( 1 )
z = GetToolChangeStart( 2 )
a = GetToolChangeStart( 3 )
b = GetToolChangeStart( 4 )
c = GetToolChangeStart( 5 )
SafeZ = GetSafeZ()
if SafeZ > z then StraightTraverse x, y,SafeZ, a, b, c
StraightFeed x, y, z , a, b, c

on the face of it, I'd have thought this would be easy to implement (don't most people want their Z axis to rise automatically when a tool change is triggered?). with respect to these macros - I'm not getting much with Google (ok, perhaps nothing simple!)- could some kind soul indicate what simple enties would need to go into those two macros?

Once again - all my tools will have the same distance to tip - therefore all I need is for the Z axis to raise 50mm (I turn off the spindle manually, change the tool manually, start the spindle manually - press cycle start), the tool then drops 50mm again to continue with the cutting.

Many thanks!

[ger21]

Let me play around tonight and figure it out.

[HankMcSpank]

That would be great! (and probably of a lot of use to many others too!)

Many thanks.