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Author Topic: Touch Plate Corner Finder  (Read 5328 times)

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Touch Plate Corner Finder
« on: August 20, 2018, 07:52:30 PM »
I've modified the TouchOff module to support corner touch plates that DON'T have the same thickness in all 3 axis's.

Instructions for install:
1.   Open C:\Mach4Hobby\Modules folder
2.   Rename file mcTouchOff.lua to mcTouchOff.lua.bak
3.   Copy replacement mcTouchOff.lua into this folder

This fix has been tested with MACH4 build 3804 – 3835 using a PoKEYS57CNC controller.  Make sure and test with any other builds or controllers. 

Setup Instructions:
1.   Touch Plate Height – This is the thickness of the touch plate in the Z axis
2.   Touch Plate X – This is the width of the touch plate off of the X axis.
3.   Touch Plate Y – This is the width of the touch plate off of the Y axis.
4.   XY Check below Z – This is the distance to move the tool below the material/touch plate for the X and X axis tests. (typically 2-3 millimeters (0.125 inches))
5.   Touch Plate Hole Diameter – This is the diameter of the hole in the touch plate typically at the corner of the material.  The tool will move inward enough to clear this hole when testing the Z axis.
6.   Remaining fields are set per ArtSoft instructions.  I recommend a “Prep Distance” greater than the “Retract Distance” for best results.

This modification only affects 3-point corner tests.  All other touch tests on this control function as ArtSoft designed.

Directions for finding material corner – Position tool over the corner of the material (with 2-3mm in the X and Y axis) and 5-10mm above the material.  Press the appropriate corner test button.

Let me know if you have any issues with it.
- Robert Beaubien
- Drone Plastics
-
“Dear Algebra, Please stop asking us to find your X.  She's never coming back and don't ask Y.”
Re: Touch Plate Corner Finder
« Reply #1 on: January 02, 2019, 03:31:34 PM »
This is a valuable fix-up to Mach 4. I will definitely use it.
As far as I can tell, this code requires offsets for X and Y to be identical to work on all four corners.
The typical edge finder can be used to work on all four corners.
Here's the problem:
If an edge finder uses three different surface offsets, for example, A, B, & Z  Interestingly enough, the top left corner and the bottom right corners use the same surfaces for X and Y, which is A and B respectively. However, the top right corner and the bottom left corner use surfaces X & Y as B and A respectively. 
Should the edge finder have three different offsets for X, Y, & Z , then the code needs to compensated for differences depending on the corner being probed.
Note Z doesn't change for any corner.

Does this code take in account for using all four corners of the work piece?
Thanks,
Bill
Pixel Tamer
Re: Touch Plate Corner Finder
« Reply #2 on: March 16, 2020, 08:25:11 PM »
Thanks, don't know why Artsoft does not include this. :(
Re: Touch Plate Corner Finder
« Reply #3 on: April 02, 2021, 06:08:58 AM »
Have you had trouble with the touch function not functioning all the time? When I run a command like top right corner in touch it will do random things like sometimes hitting the surface then stopping. It then comes up with n error code to do with the probe. Sometimes it won't stop when touching in the x or y move. My setup is similar to yours in that I use the same controller and touch plate.
Is there something I can check to get this working consistently?

Cheers
Re: Touch Plate Corner Finder
« Reply #4 on: April 02, 2021, 10:37:05 AM »
The code may have a bug in it, after all it is rumored that no coded project has ever been bug free. To avoid this, you should work from a point of consistency.
Try always starting your measurement from the same conditions, such as placing the probe at your starting point and then zeroing all of the axis before starting the probe sequence. This way, the code will perform all of its subroutines in the same order and in the same way.
If you encounter a setup scenario that reliably produces an error, then a bug report should be submitted with your test setup, and hopefully it will be fixed post haste.
The probe input is also a possible problem area. A touch should produce a reliable glitch-free signal that the software can detect accurately. A small capacitance (about 0.01uf to 0.1uf) across the probe to ground, should guarantee a clean signal to the software.
Bill
Pixel Tamer
Re: Touch Plate Corner Finder
« Reply #5 on: April 03, 2021, 07:03:04 PM »
Thank you for the info. I have tried the things you suggested and now I get through the sequence up until the x axis move. It will touch the plate then I get and error message "ERROR - no contact with probe" even though the touch plate and probe are touching and the active signal is lit up to say that it has been activated.
I am a newbie when it comes to the Lua code so don't know where to look to see the problem. Any hints?

Cheers
Brent
Re: Touch Plate Corner Finder
« Reply #6 on: April 03, 2021, 09:58:10 PM »
I don't know where to take you from here. I don't know much about LUA either. I don't use Mach4. You need to find another Mach4 user to help you through this. If there is a bug in the code, the author needs to handle it.
In the mean time, all I can add is that you try different approaches to getting X to work. I can't believe that nobody else has the same issue.
Just one thing more. Is it possible that you have a short to the probe? The motor spindle may be grounded to the frame, perhaps poorly, and the ground is interfering with the touch process. You may have to reverse the probe wiring between the probe and the edge-finder.  Early hobby CNC machines were made with wood or plastic and hand routers. Now almost everything is metal and electrical ground is everywhere. When i upgraded my CNC to metal, I found my spindle grounded and I eventually isolated it at the clamp to make the probe work again.
good luck,
Bill
Pixel Tamer
Re: Touch Plate Corner Finder
« Reply #7 on: March 20, 2022, 06:57:24 PM »
Hey Brent,

did you by any chance find a fix to you probe problem? I am running into the same problem with pokeys57cnc. m6 script works flawlessly, but I am having issues when i try to use any of the modules within Mach4 center finding for example, it will start the process then I'll get a random error " no touch with the probe" not on any particular axis.