Help please...Problem with Ref Z when using touch-off plate.

[DEWilliams]

Hi all,

A few days ago, I finished a new box for housing all the electronics for my cnc
router, and when I plugged it in, everything was working perfectly as before. (I got lucky, or so I thought)

Until a few minutes ago, that is. I went to the Diagnostics screen, and did a Ref Z to the
touch-off plate.  Usually, it makes contact, stops, and then backs off a hair and I'm ready to
roll. This time however, it smashed the .0236" bit into the plate and snapped
it off. Yikes! Then I changed bits, and decided I'd hold the plate up in the
air and see if it did the same thing. This time it stopped, and started backing
off, but continued to keep backing off with no end in sight. This is odd
behavior for this, and I'm wondering if anyone has an answer to get things back
as they were.

I had just changed some steps values in the Motor Tuning section in an attempt to gain a little more accuracy. 
I was off about .015 over an 18" length, and wanted to try to tighten that up.
I don't know if that is what caused the issue or not, but I've heard that things like that can happen.
The question is, how to get it working properly again.

If there's a better way to set the Z height than this, I'm all ears.

Thanks,

Don Williams

[Tweakie.CNC]

Don,

Looks like it is recognizing contact with the touch plate OK but the feedrate may be too fast and the overshoot broke the cutter.

Perhaps if you attach you script it may help to find the problem.

Tweakie.

[DEWilliams]

Script?  What script?  It's just Mach 3...no script, except whatever is resident there.  ?

[Tweakie.CNC]

Sorry Don I was getting confused between Ref Home and Auto Tool Zero. Changing your step values has probably altered your home position.

I, along with many others, use the Auto Tool Zero (as described in the second half of this page http://www.cooperman.talktalk.net/files/17.htm) perhaps you may consider this as a better way for tool zero.

Tweakie.

[DEWilliams]

Thank you, kindly.  That looks like a great solution.  I had a feeling that adjusting my settings was what messed things up.

[Tweakie.CNC]

Don,

There is lots on the forum if you do a search for 'auto tool zero' or 'touch plate' it may seem difficult at first to set it all up but as you get into it then it becomes more doable. 

Tweakie.