Making a Height Gauge PT2
 
A Height Gauge is a wonderful little toy that can be used to set the height of tools and fixtures.  Being fairly simply to use it beats other methods of touch off the tool simply because of the spring in the surface and the accuracy of the gauge.
Return to Making a Height Gauge pt1
Start by putting a good end mill upside-down in a holder.

My spindle is NOT and R-8, so the tool holder looks a little different.  Don't worry, this will work the same way in an R8 collet, or whatever you have.

 

If you have an "Actual" height gauge you can pretty much skip the next few steps and just measure it.
   
Put the tool in the spindle and tighten it.
   
Bring the flat edge of the tool all the way down to the table surface.

If you have a Square Column conversion, just get close with the CNC, then loosen the quill lock and press the tool against the surface, and re-lock it.

To be exact, what we care about is the fact that the bottom edge of the tool is at 0.0000
   
Using you software click "Zero Z" or something similar.  The DRO must say 0.0000
   
Drive up (with the Z Axis) and stick the height gauge under the tool.

Drive down until you find a number you like.  The number is arbitrary, just find a place that you can repeat.

You'll notice we added a spring under the plunger, the little spring inside the indicator didn't press very hard with the aluminum plug on the top.  We just twisted the spring on there and kept going.
   
This is a close-up of the dial from above.

We stopped going down when everything points straight up.

Notice the little black dots on the face.
   
At this point the DRO from the controller software will tell you your height.

Ours says Z 5.6702" from the table.

This is YOUR OFFSET.  REMEMBER THIS NUMBER.
   
When using the gauge plug your offset into your controller software.

We just dropped the 0.0002 off the end.  This way we just need to remember 567 and we're good to go.
   
Put a tool (any real tool) into the machine.
   
With the Touch Correction turned on and your offset plugged in, click the tool "Touch" button.
   
The offset of the tool will now be set and the Z axis DRO will say your offset number.

You are now good to go, You can begin machining, or touch off the next tool for the run.

Be sure to save the tool table when your done "touching-off" tools
   
Some of you will be saying "WOW that's cool", others will be saying "I don't get it".

For those who do get it:

It's possible to use a similar approach to get the Z offsets for fixtures as well, plus it's quick and accurate.

For those who don't get it:

Look at it this way, a few pictures up you see an end mill pressing down on the gauge.  My hands on the dial are at their known point (Big hand at 0, little hand straight up).  So I now know that the bottom of the end mill is EXACTLY 5.670" above the surface (top of table).

The steps following that tell the controller that the tool 14 (my 1/2" 3 flute) is EXACTLY 5.670" above the table.

Since the controller knows where 5.670" is, it now also knows where 0" - 20" are.

So I can say "Go to Z 0""and that end mill will just touch the table, or I can say "Go to Z 1"" and it will go to exactly 1" above the table.
   
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