Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: PeteG on March 07, 2020, 01:01:13 PM
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Hi
I have a home-made CNC machine – surprisingly accurate – but it doesn’t have an auto tool changer. So far, I have been setting the Z height between different tools using the ‘bit of paper’ method, then resetting Z zero in Mach 3.
This works well enough for my purposes, but I felt that there has to be a more sophisticated way. So I tied into my emergency stop circuit and with a connection to the cutter and another to a 0.0015” feeler gauge. I can lower the Z manually and the machine stops instantly when the cutter touches the gauge then I zero Z. But 0.0015 is a bit flimsy and I want to use something more rigid.
I have a piece of Aluminium which is 1.77mm thick. How can I use this to set Z zero?
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Hi,
So I tied into my emergency stop circuit and with a connection to the cutter and another to a 0.0015” feeler gauge.
That is no the correct way. When your machine Estops it attempts to stop instantly and it will lose steps and therefore lose
its 'reference' or 'home'.
There is a Gcode instruction especially for 'probing' called G31. for example:
G31 Z-1 F10
It is assumed that the tip of the tool is say 1/4 inch (approx.) above the feeler gauge/touch plate. The Z axis will descend
towards Z=-1 inch at 10 inches per minute UNTIL it detects a probe strike event on Machs Probe input, at which point it will
use max deceleration to stop. At that point you can use the Z axis DRO to set your Z offset.
Craig
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Thanks Craig