Work with probe

Doesn't the tool table only provide for one offset per axis? or have I missed something?

If it is only one offset then that doesn't help when probing a corner or circle as that needs two or three offsets respectively (assuming +X is 0 ie the probe tip radius) and even for single axis probes I'd have to change it each time.

Looking at the code some more, the references to tool_offset[] seem to apply to X, Y and Z so that's not what I'm looking for.

However, probe_screen.py calls 'xminus.ngc', 'yminus.ngc' etc and somehow gets the result of the probe therein back into the Python code (probed_position_with_offsets()? is it the print from xminus.ngc that gets fed back into python? the python stuff doesn't reference 5061 or 5062).

When I get back in front of my mill, I'll try hacking xminus.ngc as, if my guesswork is right, a tweak along the lines of:

might do the trick.

ruffle wrote: Doesn't the tool table only provide for one offset per axis? or have I missed something?

Maybe I am the one missing something, but the offset between the probe ball and the spindle axis can be described by an X offset and a Y offset. If you insert the probe into the spindle and then G43 the centre of the ball will be where the encoders say it is.

Your changes to the probe routine will probably work fine too, though.

Having engaged what's left of my brain... You're right and I'm an idiot ^[1]

If I change xminus.ngc and friends so they do:
and setup tool 99 that should do the trick.

Still might be nice if this was built into probe_screen.py though. I'm sure I'm not the only cheapskate that'll baulk at the cost of a Renishaw and buy a cheapy probe.



[1] - I should know better than to give a moments credence to the silly thought that AtP gave bum advise on something mechanical :laugh:

ruffle wrote: Can I suggest a modest but potentially very useful mod for this?

A probe tip offset/compensation method.

I've bought a probe (admittedly not a Renishaw!) and getting the tip centered to any reasonable accuracy is turning out to be a right pain.

Given that the probe would always be mounted in the same orientation (not unreasonable as the cable kind of dictates a natural place and I'd mark the front of the probe body and always use that facing the front of the machine), I know that probing in -X it measures 0.12 less than +X, +Y some 0.08 more than +X and -Y 0.04 less than +X.

It's easy to measure the offsets by turning the probe through 90 degrees and probing a known face in +X so if I could enter those differences into the probe routines (it doesn't even need to be in the GUI, editing the .pref file or setting a value in the machine's .ini file would be fine) and the calculations took account of the offsets I wouldn't need to worry that the probe tip is not 100% on centre.

Any chance of getting this added? or is it already there? I see references to 'tool_offset[]' in probe_screen.py but that array doesn't seem to be set to anything (warning my Python skills are less than my levitation skills so I could be missing the blindingly obvious!).

Ruffle: You have it half right. -- no insult intended. In the sense that 90 is half of 180.

I've implemented some probe calibration code. I've added "wings" to my probe to let it be rotated 180 degrees against a stop. I call the two positions A and B. I use a round hole for calibration. I took a drill bushing and glued magnets to the bottom so that I could stick it to my table or vise. The diameter of the calibration hole doesn't matter.
Then:
1 -- Rotate the probe to the A position.
2 -- Find the center of the hole (I use a subroutine I call calibrateA)
3 -- Rotate the probe to the B position.
4 -- Find the center of the hole (I use a subroutine I call calibrateB)
The true center of the hole will be *exactly* the average of the two values -- exactly to the extent that the probe was rotated exactly 180 degrees.

You can then compute the offset necessary. My calibration routines do that and display the new computed offset and any previous computed offset. I use the A position for my measurements, so that's the offset I compute. My probing routines automatically add the offset. (It should be noted that the calibration routine also corrects for errors in the collet that is used to hold the probe.)

Some results (on an old Bridgeport Clone I converted with ball screws). The probe cost me $79 (new on ebay).
1 -- When I probe a center, it regularly repeats to 0.0002 inches on both axes.
2 -- I calibrated the probe, used it, and then removed the probe and calibration fixture from the machine. I later put the probe back on the machine (its not necessary to recalibrate it.) I forgot that it had already been calibrated and calibrated it again. The difference between the old and new offsets was zero (to four decimals) on the X axis and 0.0001 on the Y axis.

Since the probe had been driven into the table by bugs in the software the offset was around .018 in one axis (I don't remember the other offset).

I'd like to be able to provide copies of my routines, but they probably aren't ready for prime time.
1 -- There is no documentation
2 -- They are integrated with the software I use for my MPG. That let's me do things like:
A -- Using the MPG move in some direction.
B -- Push the probe edge button. The probe will move in the same direction as the last move to find an edge.
C -- Push the set zero button. The last axis that was be probed will have the last probed position set to zero in the current coordinate system.
D -- Move somewhere else
E -- Push the probe edge button. The probe will find the new edge
F -- Push the half button. The current axis value will have zero as the half value of the new probed position. In other words, the axis was zeroed to the midpoint (line) between the two probed points on the axis.

Ken

I love the screen but I am having a hard time getting the probe screen to display the buttons. At this point I am confused as to were these files are and how to get them. Can someone please help?

The following files from the archive are placed in:

your-folder-configuration/python

probe_screen.py

your-folder-configuration/your_subroutine_path

all from folder "macros"

your-folder-configuration/probe_icons

all from folder "probe_icons"

~/

.axisrc

thor44 wrote: Can someone please help?

Hopefully, you do not perceive this folder name as literal (your-folder-configuration/your_subroutine_path).
These names should be replaced by the name of your configuration folders.