Author Topic: question re compensating for probe offset  (Read 3544 times)

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Offline vinythewheel

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question re compensating for probe offset
« on: November 04, 2013, 08:51:00 AM »
Is that possible to edit probing button?
For example:
I want to find the center of a circle. If i want good accuracy, i have to find the circle once then turn the spindle 180 degre and find center again. The résulting real center is the average of both mesurement. That way, all error introduce by the ecentricity of the probe, the TIR of my spindle, ... are wiped off.

To be able to do it, i have to modify the probing macro. Is that possible?
« Last Edit: November 04, 2013, 11:38:52 AM by DaveCVI »

Offline DaveCVI

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Re: question re compensating for probe offset
« Reply #1 on: November 04, 2013, 11:49:20 AM »
Hi,
I moved your post out of the announcement thread to keep things tidy.

Is that possible to edit probing button?
Yes, MSM is fully customizable. How to customize MSM is covered in the mill user manual.

For example:
I want to find the center of a circle. If i want good accuracy, i have to find the circle once then turn the spindle 180 degre and find center again. The résulting real center is the average of both mesurement. That way, all error introduce by the ecentricity of the probe, the TIR of my spindle, ... are wiped off.
To accurately find the center of a circle, you can use the MSM circle center probe routines. Note that MSM supports the ability to find both the center of circular holes and circular extrusions.
I also suggest that you read the section of the manual about probe calibration. The MSM calibration process will take care of the types of errors you mentioned. It is important that each time you mount the probe, that you use the same spindle orientation (since there is not a way to "Read" the orientation of the spindle, there the software can't compensate for an arbitrary orientation).

To be able to do it, i have to modify the probing macro. Is that possible?
The probing library for MSM is not offered in source form. 

Dave
Author of the MachStdMill Extensions for Mach3
www.CalypsoVentures.com

Offline vinythewheel

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Re: question re compensating for probe offset
« Reply #2 on: November 07, 2013, 11:08:58 PM »
my problem is that I bought the probe at 199$ on eBay and there is no way to calibrate it. pain in the ass. while measuring a 123 block I can calculate the ball diameter easily. if I want to know hole diameter, even with a offset probe, I will get it acuratly. but if I want to know where is the hole center or the edge of my part, there is only one way: touche the part, then turn the spindle 180°, then touch again. the average of the two position will be the position of the edge. fortunately, my spindle motor is a brushless servo DC motor with step and Dir drive. so implementing your probe code will be very useful to me. of course I know that very few guy have servo on they spindle. so its a lot of work for few customer.
if I edit the but on in your probing wizard. is there a way to call the same code twice and print or use the average?

Offline DaveCVI

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Re: question re compensating for probe offset
« Reply #3 on: November 08, 2013, 12:03:03 AM »
if I edit the but on in your probing wizard. is there a way to call the same code twice and print or use the average?

OK, here are some steps to get you started in trying this out...

The probe op results are shown by MSM in the probing panel. The circle routines display X and Y (center position) as well as X,Y width and diameter (X,Y = diam for a circle, different for a rectangular pocket).

I'd do the following manually to see if you get the results you want - then you can code up a button.

For a first step you can do one op, get the values, do the 2nd op and compute. The DROs are also accessible from a mach script, so the button code could become a wrapper - it would do one op (make the call the button already does), get the dro values for the result, rotate the spindle, make the probe op call again, get the values, crunch numbers and away you go.

BTW- the primary support forums for MSM are here:
www.CalypsoVentures.com/forums

Dave
Author of the MachStdMill Extensions for Mach3
www.CalypsoVentures.com