Touch plate setup for zeroing X, Y and Z

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4DThinker
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Joined: Wed Oct 07, 2015 10:57 am
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Touch plate setup for zeroing X, Y and Z

Postby 4DThinker » Fri Jun 23, 2017 6:53 pm

I often set up projects using the bottom left corner of my work for the origin point. I add in an offset of 1/2 the diameter of the bit I'll be using, which means to set zero I touch the edge of the bit against the left and bottom edges of the workpiece for X and Y axes respectively.

After getting a touch plate installed for setting Z, it made me wonder if I could use it to set X and Y as easily. That became my challenge.

Adding buttons on the LinuxCNC screen, subroutines those buttons could run, and making it all work took several days of reverse engineering the interface but I now have it working.

LinuxCNC.png
LinuxCNC.png (113.68 KiB) Viewed 2538 times
I use a rectangular bar of aluminum for my plate (rather than a round puck). I have it set up so I can move the bit to within an inch or so of the X or Y edge, put the plate in between and against the wood, then click on the appropriate Set button you can see on the right edge of the screen above. The routine moves the bit slowly toward the plate until it makes contact. Zero is set allowing for the thickness of the plate, then the bit moves back an inch.

Now that I've figured out how to do this, I'm looking into how to split the X and Y buttons so I can choose to zero against left or right, and bottom or top edges.

4D

Bobtail Farm
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Joined: Tue Mar 22, 2016 8:32 am

Touch plate setup for zeroing X, Y and Z

Postby Bobtail Farm » Wed Jun 28, 2017 6:04 am

Nifty.

4DThinker
Posts: 254
Joined: Wed Oct 07, 2015 10:57 am
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Re: Touch plate setup for zeroing X, Y and Z

Postby 4DThinker » Wed Jun 28, 2017 8:26 pm

Thanks, Bobtail Farm.

In our college shop we have a CNC shark with a touch plate, and 2 Probotix CNCs. Every semester my students have been asking why we don't also have a touch plate for the Meteor and Nebula. The original controller for my personal Meteor died recently and Len was gracious enough to replace it with their new Unity controller. I had to rewire all my stepper motors to get it to work, then run their configurator app. Seeing that there was a choice for using a touch puck while running the configurator I realized I could now make and wire up my own. They have all the needed info on their Wiki page.

Setting it up to touch off the X and Y axis was just a bonus challenge to keep me busy for a few days this summer while I wait for classes to start up again in the Fall.

I've seen a way to have the software check all three axis during the same routine using a short section of pipe with a 1/4 section notch in it that you place on a corner of your work piece. The bit gets jogged into the pipe. The Set Origin routine has it move left/right until it touches the pipe for X, then forward/back for Y, then down to check Z. A little math deduces where 0,0,0 is and it doesn't matter what diameter the bit is. That will be my next challenge. The code needed should be simple. Making the sectioned pipe piece will be a bit more trouble.

4D


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