Question about Z ref.

[IvanVelchev]

Hi. I have a question about Z reference on my cnc router. I always set and use Z ref. on top of my material, and later on I always set Z=0 on top of the sheet of the material. Every time I change the thickness of the sheet , I change Z ref. to zero on top of the sheet. This makes Z ref. always equal to 0. Can I use some surface on my router as a Z ref. and not to change it every time I change the thickness of the material or it is necessary Z ref. to be changed together with Z=0 on the material. Also if I change Z ref. on a different height , and if I want to measure only one tool, should I remeasure all of the tools again witch are previously measured on different Z ref. Thanks in advance.

[Dave_C]

You can set your Z anywhere you like, just make sure you G Code knows where Z actually is! Using the top of the material is normal, trying to use the bottom of the router means that anytime you change a tool the G-Code is not going to cut at the same depth, unless of course every tool is set to the same length. (Not a likely occurrence)

Routers do present a challenge when it comes to changing tools when you don't have anything but a collet to hold the tools.

Dave C.

[cncsnw]

Z Reference is about tool measuring, and has no required relationship to the material you are cutting, or the location of your part zero.

As Dave_C points out, measuring tool height offsets is only useful if your machine allows you to change tools, while retaining a repeatable length for any given tool.

If you are measuring tool heights and using tool height offsets, you can choose any surface you want for touching off tools as you measure them. Z Reference is set on that tool-measuring surface. If you use a surface that is separate from any material you may be working on (e.g. a fixed block sitting on the work table or machine frame), then you do not have to reset Z reference every time you change your material.

One thing that confuses many people is that the Z Reference value displayed in the Offset Library is displayed in local coordinates (i.e. as a height above or below the current part zero), even though it is really maintained as a machine-coordinates position (independent of the current part zero). Because of that, the number displayed for "Z Reference" will change whenever you set the Z axis part zero at a different height, even though it continues to represent the same level on the machine.