Z Problems! (New to CNC)

[LarryBoyd]

Hi,

I work in a school and we recently purchased a CNC machine to expand the capabilities of the department. Since buying it we have not been able to run it properly without running into a few problems. The first issue we had was it carving in reverse, this was sorted quickly by changing the X and Y axis'. The second more annoying problem is that when running a job it will do part of it then it will move up too much on the Z and continue to run cutting at the wrong depth, then not cutting on the material at all. I've slowed down the acceleration on the Z axis, made sure all parts are tightened correctly and made sure it isn't hitting the end stop but still the problem occurs.

Please help.

I didn't find the right solution from the Internet.

References:-
http://forum.vectric.com/viewtopic.php?f=2&t=21518
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Thanks!

[Techgraphix]

Yes, there can be several causes (beside a malfuntion of the machine itself)
Is your toolpath generated correct? If you set the tip of your tool to the surface = zero, the all values, exept the save-Z an quick movements (G0) should be negative (lower than zero. You can check the G-code (i presume that your machine is working with G-Codes??)
I don't know which software you use to make the model and generate the G-Codes, but in that program you should also set the surface to zero and all engraving must be blow that surface, else you will move in air...
Normaly, when there is a malfunction (too weak steppers, too high acceleration or speed, your spindle will come out too low, so i think this is not the case...
Just check if your program is set right and generates the right codes..(ie negative Z for engraving)
Kees