Z Axis Plunging too Deep into part < part zero, tool offsets, turns ratio >

[martyscncgarage]

On a Mill
Head up is Z+
Table toward the operator is Y+
Table to the right of the operator is X-

Did you calibrate all three axis?
Your turns ratios on your three axis are all different. Since you posted no pictures of your machine, no description of how the axis motors are connected to the screws, we have to guess

Axis Label Motor Encoder Lash Comp. Limit Home Dir Screw
revs/in counts/rev. (inches) - + - + Rev Comp
1 X 6.4068 4000 0.0000 0 0 1 0 N N
2 Y 8.0081 4000 0.0000 0 0 0 1 Y N
3 Z 5.0787 4000

You have to ascertain that your axis are moving correctly and accurately.
A couple of documents attached for that.
Remember, I am guessing here. I can't see how you have things configured. These are merely suggestions.

[milling]

I took some photos of the mill and control panel.
Also I started over with everything off/unplugged (computer and acorn board) and made a very simple program using intercon called "test"- which consist of a center drill bolt circle and a milled out pocket. I homed the machine out and then set the part 0 using a 1/4" endmill that will be used in the 2nd op. Just wanted to make sure the tools are being compensated for length- and they are as far as I can tell. I set part 0 by touching off on the block of wood in my vise, chose "center" and F10 'd on X, Y, and Z- and picked the correct tool for Z. When i ran the program it ran perfect. I did a feedhold at a couple of points and measured the tool tip to the part and it made sense- again part ran perfect.

I shut everything down again and booted everything back up again and chose another simple program called "test drill". I went through the exact same steps of homing and setting up part 0 the same way. When I ran this and did a feedhold you can see the tool tip is about 1/2" off from where the WCS shos it to be- just not sure why its doing this? I have attached the photos of my setup and also a copy of the G code for "test" and "test drill". Is there something you see within these simple programs that would make one work and not the other?

Hope this helps and you can let me know what Im doing wrong!


Thanks again

[milling]

Marty, I saw your comments and understand. I believe I went through the turns ratio and set that up correctly. I messed with the lash a little bit and watched videos but still not 100% confident on it so I left lash at 0 for now. Even with lash not put in it should not do what its doing- I believe lash is merely for increased accuracy- but the Z axis is a mile off- sometimes. I sent you some photos and a couple of very simple intercon programs. One ran perfect and the other one the tool was about 1/2" off and would have plunged about 1/2" into the material had I let it continue to run.

Thanks

[milling]

Confirming that my axis are moving in the directions you have stated- so there should be no issue there

[cncsnw]

Each time you run a program, use the Feedrate Override and Feed Hold to slow down the initial Z-down movement, and to pause when the cutter is maybe 1/2" above the stock.

Then look at the Z axis position shown on the main DRO; at the Z axis distance-to-go on the distance-to-go DRO; and the tool (T) and height offset (H) numbers displayed in the status window.

If the problem occurs, take a picture showing the entire screen at that point. Post it, along with a fresh report, and a copy of the program file.

Either you are making a mistake in tool and part setup; or you are making a mistake in the part program; or your control installation is losing position on the Z axis. My bet is on that last one.

[cncsnw]

When it looks like it is going to go to deep, after you have taken the screen picture suggested above, cancel the job (press ESC), then press Tool Check to send Z back up to home. If it does not go all the way up to where you previously homed it, then it has lost position.

[martyscncgarage]

What is the pitch of your ballscrews?
Are all your axis motors direct driving the ballscrews?

Feedrate over ride as Marc mentions is slap the space bar on the keyboard.

Marty

[milling]

If I do a tool check at anytime it returns to the home position
If there was a problem with the drive why would it work properly sometimes? Seems like if I lost steps it would never work properly
We’re u able to look at the two programs I sent?
One worked perfect and the other one was way off and would have plunged way into the material

[milling]

Axis are all direct drive

[milling]

Axis are all direct drive