Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: mlancaster on December 13, 2009, 02:57:28 PM

Title: Auto detecting and zeroing of z axis
Post by: mlancaster on December 13, 2009, 02:57:28 PM

Is it possible have MACH3 monitor a switch or something to detect the height of a part and then zero the z axis?
I  have been cutting an item that varies from part to part only in the Z height, I have been placing several down on a grid  (4x4) and using an offset to move to next cutting location. The biggest downside has been I need to touch down and re-zero every time.
it would be great to just run the g code an the first line was a command that went to the z calibration setting and recalculated the new contact point.

Title: Re: Auto detecting and zeroing of z axis
Post by: Tweakie.CNC on December 14, 2009, 06:09:37 AM

First reply deleted as I misunderstood the question.

After a lot more thought – If  your workpieces are electrically conductive and the cutter is electrically isolated from the workpiece the auto tool zero button could possibly be redefined as an OEM button and your GCode would then call a macro to touch off the surface of the work automatically for the start of each part.
On the other hand if the workpiece and cutter are electrically connected (both ground) then the alternative would be to use a touch plate (as I and many others have done) but due the proximity of fingers I do not think it would be wise to perform this operation within a running program so placing the macro within the auto tool zero button and manually clicking on it would be preferable.

Tweakie.

Title: Re: Auto detecting and zeroing of z axis
Post by: mlancaster on December 14, 2009, 01:49:15 PM

Thanks, my cutter is a router and i'm cutting a wax block, so nothing is conductive. Could i mount a simple contact switch (or proximity switch)  next to the cutter and move to a defined offset each time to auto zero? Accuracy is not a big issue. Does this mean that i would have to create a macro to search for the contact switch or does this already exist?

Title: Re: Auto detecting and zeroing of z axis
Post by: Tweakie.CNC on December 14, 2009, 03:02:34 PM

After reading other threads here, on this forum, I started using a touch plate for tool height setting and will never look back. A search for 'touch plate' will provide all the info you require but you can, if you wish see how I did it here:- http://www.cooperman.talktalk.net/files/17.htm

Tweakie.