I am having some issues with probing in mach4. I seem to be able to get everything to work fine but for the life of me I can't get the 2 point outside centering to work.

The help button for this operation seems to say the probe needs to start roughly centered over the top of the part. When I press measure center y the probe moves in the y+ direction briefly then stops giving me an error that it has reached the limit of the move.
If I try starting the probe beside the part it gives me a probe interference error when the probe touches the part.

I can't seem to understand how this is suppose to work. When I adjust the approach and width options it changes the amount the axis moves but no matter what I do I get no z axis movement at all.

I have tried nearly all of the other probing options and all the rest seem to work exactly like expected even the inside centering found under the same tab.

This may or may not be related but when I probe using the probing tab the probe will touch the part then retouch at a slower speed. If I use the probing wizard it doesn't do the second slow speed touch it only touches once.

After playing around with it more I am sometimes able to get a z axis move when I manually bump the probe with my finger. When this happens it will stop again. So it will start with a y+ move if I bump it I sometimes get a z+ move if I bump it again I get another y+ move.

The movements are pretty nonsensical if you ask me? Still have zero problems with all other probing.

It sounds like you have not entered the width of the Y axis of the part.    Mach needs to know the approximate size of the part before it can complete the routine.

I have still been unsuccessful at getting this to work. I have set the width to the exact dimension, smaller, and larger. The probe always moves half the distance entered into the width as expected but what I don't understand is why it just stops after making the move.

I can sometimes get the probe to complete the z move but only when I touch the probe on the initial x or y move which is unexpected. Shouldn't the probe complete the z move immediately after the initial x or y move without the touch? The probe is above the part at this point so there is nothing for it to touch.

Even when I am able to get the z axis to complete its move it still just stops after moving the distance I input for the z move.

Are you sure you have the logic for the probe the right way round.

If you enter the following line in to MDI it should move 25mm/1" in X and stop if you do not touch the probe, do it again and touch the probe and it should stop

(for mm)
G91
G31 X25. F50.

(for inch)
G91
G31 X1. F2.

I have the same problem with any of the probing actions that require moves in more than 1 direction eg finding an outside corner or measuring the diameter of a boss. If you search through the forum there are several others reporting the same issue and no interest from Artsoft in fixing it. 

We have tested this tons of times and I had them make a video about it. The probe is a little to complex for people to use. So we came up with the touch module that is in the router screen as a more simple way to do probing.  We have a new guy starting next year and I can make it his first job to simplify / streamline the probe functions.

The difficulty I was having with the probing was caused by the way the ESS motion controller executes the G31 probing. By default the ESS reports a probe failure if a G31 probe move does not result in probe contact. The latest version of ESS plugin has an option to not fail the probing if a G31 completes without probe contact.

I think some of the LUA code in the probing module is a bit dangerous. There are a number of places with G0 and G1 moves. I think these should all be G31 probe moves so that if the probe makes unexpected contact the motion stops. With G0 and G1 moves if there is also an incorrect work offset or probe length active, then there is a high probability of crashing and damaging or destroying the probe. It would also be useful if the Probe screens had X, Y and Z axis DROs particularly with the option to display distance to go so it is easy to see where the probing is moving to.

Keith

I am sick of hearing about the probing issues so I think it is time for an update. I don’t know if I can make it work for everyone but I am going to try!

I will have it all done with G31’s and if it hits when it shouldn’t it will fail out.

After sitting here and thinking about this and I would like to make a wizard style probe interface that will prompt you for every step with graphics. Would that work for you guys? My goal is to have it so simple my kid could use it!

If you want to run it from the Gcode file that will not work out but I don’t think anyone is doing that. We can do Lua or C++... I am sort of thinking C++ because I don’t want people modifying. Only thinking please give your input