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Author Topic: Touch Off Plate - DIY Depth Sensor ?  (Read 5268 times)

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Touch Off Plate - DIY Depth Sensor ?
« on: June 20, 2007, 11:50:25 PM »

I have a DIY CNC machine running mach3.
I’m new to mach3 and to CNC machines; I’m trying to mill a PCB.
I’m using a 0.015 stub end mill 2 flute

I’m having depth problems, I always cut to deep or two shallow.
I need to cut Z-0.0075  down from Z0 (Z0 = the end mill just touching the top
of the material).

My problem is that I’m breaking my end mills because I can’t set them correctly
down on the material. (I level my work area via 4 screws at the corners)

Should I build and use a touch off plate ? I don’t know what to use.

I’ve heard about some kind of spring loaded depth guard that presses on the material each plunge. Is there a web link, How do I ?

I’m also thinking about adding a DIY vacuum modification.


Is there anything I can build that will provide realtime feedback of the current depth
so the program can make sure it’s always at Z–0.0075 ?

What other DIY solutions can I use ? I don’t want to spend $$$ on ready made solutions.

What about a pressure sensor ? That way I could do somthing like this ...
   if ( getEndMillPSI ( Spindle_POS ( Z ) ) >= dec_to_PSI ( 0.0020 ) )

         JOG ( Z, ( Spindle_POS ( Z ) - 0.0001 ) );

HOW can I build a DIY pressure sensor ?


« Last Edit: June 21, 2007, 12:04:06 AM by deleteallusers »

Offline Greolt

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Re: Touch Off Plate - DIY Depth Sensor ?
« Reply #1 on: June 21, 2007, 12:35:19 AM »


There has been a lot of posts about "Touch Off Plates"   That's how I learned about them.

If you follow this link it will take you to a thread I started on CNCzone and explains my method. 

It may or may not be what you're looking for.

Can't help with a "spring loaded depth guard"


Also regarding a vacuum hold-down that would be suitable for PCBs take a look at this one.


I have not used mine for PCBs but I'm sure it would be good and it might give you some ideas.