Help Homing with 4th Linear Axis

[carllance]

Have dual head CNC Router, thus X/Y/Z/W. Typically the 4th axis is called "W" when it's not rotational, as I understand.

No matter what I try, the homing/refall button just doesn't work properly. It typically homes one or two axis, and skips the others. Also the X axis will run into the end of the axis and keep trying to go, regardless of the limit switch, which I verify is working....

Any help/suggestions would be great!

Thanks!
Carl Lance

[DaveCVI]

Hi Carl,
Alas, you are into a situation here that I don't have first hand experience with.... so be please aware that I'm "winging" this response...

Have dual head CNC Router, thus X/Y/Z/W. Typically the 4th axis is called "W" when it's not rotational, as I understand.

Yes, My understanding of the convention is that
X,Y,Z are linear
A, B, C are the corresponding rotary axis numbers
and U, V, W are the corresponding (to X, Y, Z) 2nd linear axes.

But.... mach only has X,Y,Z,A,B,C and Spindle in it's Ports & Pins setup dialog. So I'm not sure that mach knows how to support U,V,W directly.

On the other hand, I think that mach has been made to support gantry style routers; it's just that I've never done it and so don't have much help to offer. I'd suggest looking around the machsupport forums for gantry homing topics.

No matter what I try, the homing/refall button just doesn't work properly. It typically homes one or two axis, and skips the others.

Homing in mach is controlled by a script.
In MSM that script is
C:\Mach3\ScreenSetMacros\MachStdMill.set\Masters\Scripts\All-RefAllHome.m1s

That MSM script has two ways to home the machine:
1) The default is to do exactly what the stock mach home/ref script does. This is probably what is causing you trouble as that code only homes Z, Y, X then A in irder and it does not wait for each axis to stop before starting the ref home motion for the next axis.

2) By setting a constant in that script it can be made to home all 6 axes, sequentially, while waiting for each axis to finish before doing the the next one.

I'd guess that any gantry homing solution you find will involve some custom ref home script logic. This is the MSM script that you would need to modify.

Please refer to the MSM user manual re customizing scripts etc - so that you do not customize it only to see it replaced when you next update MSM.

Also the X axis will run into the end of the axis and keep trying to go, regardless of the limit switch, which I verify is working....

When you say "it's working" - what do you mean by that (as it's not "working" entirely or the axis should stop) ?
Check that the "C" home switch input signal is enabled in the mach ports & Pins dialog.

Any help/suggestions would be great!

Thanks!
Carl Lance

Sorry I don't have more info for you on this one.

Dave