As always reference the LinuxCNC manuals and the LinuxCNC Wiki for more information.

Tool Touch Off

If you have pre-settable tools ie. you can take the tool out of the spindle and replace it without loosing the Z position or you have a tool turret like in a lathe or a tool changer in a mill then you need to understand how to touch off tools and store the offsets in the tool table.

Tool Table

Using the Tool Table Editor you can set up the diameter of your tool or in the case of a lathe the tip diameter and front and back angle and the orientation. More information on configuring the Tool Table Editor is in the LinuxCNC documentation.

Note
Don’t try and set the offsets by editing the tool table, the length offsets are from the machine origin.

Basic Steps

Basic Steps to setting the Z offsets
  1. Set each tool Z offset to a common point and store that in the tool table.

  2. Use one tool to set the Z material offset and store that in the coordinate system.

Setting the Tool Table Offsets

The first thing you must do is home the machine before setting tool table offsets.

Begin by picking a spot to touch off to that all tools can reach. On a mill you might use the top of the fixed part of your vise. On a lathe you might use the spindle face. In any case what the objective is to set each tools Z offset to some common point so each tool when loaded with Tn M6 G43 the Z end of the tools will all be the same height.

Using the procedure found in the Mill Tool Touchoff or the procedure found in the Lathe Tool Offsets section of this tutorial we will set the offsets for the tool table first.

Setting the Tool Table Offsets
  1. Go to the DRO tab and verify that there are no offsets in place for G92

  2. Load the tool

    1. Manual tool change put the tool in the spindle and do a Tn M6 G43 where n is the tool number in the MDI window.

    2. Tool changer just do a Tn M6 G43 in the MDI tab to load the tool.

  3. Verify that Machine > Touch off to fixture is selected.

  4. Jog the tool to the fixture point and using the dowel method position the Z end of the tool.

  5. Verify that the Z axis radio button is the selected axis in the Manual Control Tab

  6. Press the Touch Off button and select T Tool Table from the drop down list box for Coordinate System.

  7. Leave the number at 0.0 and press OK

Using the above procedure set the rest of the tools making sure to have the correct diameter and in the case of the lathe the orientation of the tool.

Setting the Material Offset

Pick any tool that can touch off to the Z0 of the material. Examples of tools that may not work are a parting tool or a threading tool on a lathe.

Setting the Tool Table Offsets
  1. Load the tool

    1. Manual tool change put the tool in the spindle and do a Tn M6 G43 where n is the tool number in the MDI window.

    2. Tool changer just do a Tn M6 G43 in the MDI tab to load the tool.

  2. Verify that Machine > Touch off to workpiece is selected.

  3. Jog the tool to the top of the material and using the dowel method position the Z end of the tool.

  4. Verify that the Z axis radio button is the selected axis in the Manual Control Tab

  5. Press the Touch Off button and select P1 G54 from the drop down list box for Coordinate System.

  6. Enter in the diameter of the dowel used and press OK

  7. Go to the DRO tab and verify that you are in the G54 Coordinate system.

Now you can load each tool using Tn M6 G43 and the Z end of each tool will be the same relative to each other and Z0 in G code will be the top of the material.